JP3948631B2 - Coated high-pressure boron nitride sintered body and method for producing the same - Google Patents

Description

【０００１】
【産業上の利用分野】
本発明は、微粒子からなる均一で、緻密で且つ強固に焼結された微組織が高度に制御された高性能な高圧型窒化硼素焼結体及びその製造法に関する。
【０００２】
【従来の技術】
高圧型窒化硼素は、立方晶窒化硼素及び／又はウルツ鉱型窒化硼素からなる。立方晶窒化硼素（ｃ−ＢＮ）は、強い共有結合性に基づき、多くの非常に優れた性質を有するが、反面、その共有結合性に起因して、自己拡散係数が非常に小さいために極めて難焼結性であり、しかも立方晶窒化硼素は熱力学的には超高圧力下でのみ安定で、高温下では圧力が不十分な場合には黒鉛型相の六方晶窒化硼素（ｈ−ＢＮ）に相移転する。また、ウルツ鉱型窒化硼素（ｗ−ＢＮ）は、立方晶窒化硼素と略同様の性質を有し難焼結性物質であり、熱力学的には超高圧力下でのみ安定で、高温下では圧力が不十分な場合には黒鉛型相の六方晶窒化硼素（ｈ−ＢＮ）に相移転する。尚、ウルツ鉱型窒化硼素を、立方晶窒化硼素が熱力学的に安定な超高圧力・高温下で焼結すると条件次第で立方晶窒化硼素に相転移し、この場合には立方晶窒化硼素が混在した焼結体、或いは立方晶窒化硼素のみの焼結体となる。何れも、結合材や焼結助剤が無添加では、約２０００Ｋという非常に高い温度と同時に、約７０００ＭＰａの超高圧力を作用させなければ強固に焼結することが出来ない。しかし、このような焼結条件は極めて苛酷なもので、工業的に高密度な高圧型窒化硼素焼結体を製造する目的には不適当である。従って、高密度な高圧型窒化硼素焼結体を製造するためには、工業的に適用可能な条件で焼結する必要があり、そのためには結合材及び／又は焼結助剤の添加が不可欠である。
特に近年、高密度な高圧型窒化硼素焼結体の高性能化が望まれており、そのために高圧型窒化硼素粉体粒子が、例えば１０μｍ以下の微粒子からなる高圧型窒化硼素粉体粒子を原料とし、これを焼結して高密度な高圧型窒化硼素焼結体とすることが求められている。
【０００３】
従来、主に結合材及び／又は焼結助剤を粉体状で添加する方法により高圧型窒化硼素焼結体が製造されてきた。この場合、結合材及び／又は焼結助剤が微細であっても理想的な均一な添加、即ち個々の高圧型窒化硼素粉体粒子にむらなく行き渡る均一な分散は極めて困難である。仮にこの均一な分散が実現されたとしても、結合材及び／又は焼結助剤を粒子単位で添加するために、均一の意味にも限界がある。特に結合材や焼結助剤の添加量が少ない場合、焼結体中に結合材や焼結助剤が存在しない部分が必然的にできることになる。
現実には、多くの場合、高圧型窒化硼素粉体粒子や結合材及び／又は焼結助剤の粒子が凝集して焼結体中に塊状に存在したり、或は焼結体中で偏在する。このため、特に高圧型窒化硼素粒子が凝集して存在する部分では、結合材や焼結助剤無添加と同じこととなり局部的に未焼結で残る。また、結合材及び／又は焼結助剤が凝集して存在する部分では微視的に高圧型窒化硼素粒子が焼結体中に存在しない部分ができ、何れもでき上った高圧型窒化硼素焼結体の性能を著しく低下させる欠陥となる。
従って、上記欠陥のない、高性能な高圧型窒化硼素の焼結体を製造するために、高圧型窒化硼素粉体粒子一個一個に確実に結合材及び／又は焼結助剤を分布させる必要があり、そのために、高圧型窒化硼素粉体粒子一個一個に結合材となる物質及び／又は焼結助剤となる物質を被覆法により均一に被覆した被覆高圧型窒化硼素粉体粒子による高性能な高圧型窒化硼素焼結体を製造することが強く望まれている。
【０００４】
被覆法としては気相法、湿式メッキ法など種々の方法があるが、中でも気相法は、原理的に、（１）雰囲気の制御が容易である、（２）基本的に結合材及び／又は焼結助剤としての物質の選択に制限がなく、活性金属を始めとする金属単体物質、窒化物、炭化物、硼化物、酸化物など、いろいろな種類の物質を被覆できる、（３）結合材及び／又は焼結助剤として目的物質を高純度に被覆できる、（４）結合材となる物質及び／又は焼結助剤となる物質の被覆量を任意に制御できるなど、他の被覆法では成し得ない大きな利点がある。
しかし気相法による結合材となる物質及び／又は焼結助剤となる物質の、高圧型窒化硼素粉体粒子への被覆は、高圧型窒化硼素粉体粒子が微粒子である場合又は主に微粒子からなる粒子である場合に個々の高圧型窒化硼素粉体粒子への被覆は、以下の理由により不可能であった。
即ち、被覆されるべき高圧型窒化硼素粉体粒子が、微粒子である場合の、この被覆されるべき芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子は、粉体粒子同士の付着力が強いため凝集性が高く、殆どの単一粒子が凝集体を形成している。そしてこの凝集体は、その凝集力を上回る特別な作用を加えない限り崩し壊すことができないために凝集体をそのままで被覆しても、一個一個の粒子表面への結合材及び／又は焼結助剤による被覆は不可能で、結局凝集体の表面が結合材及び／又は焼結助剤で被覆された被覆凝集体が生成することになる。
これにより凝集体を形成する個々の高圧型窒化硼素粒子は、凝集体表面に位置する粒子では粒子表面は被覆量は多いものの被覆むらが生じたり、凝集体内部に位置する粒子では全く被覆されないという問題があった。
【０００５】
上記の問題を解決しようとして、被覆されるべき高圧型窒化硼素芯粒子粉体粒子が微粒子である場合のこの被覆されるべき芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の個々の粒子を被覆する目的で粒子を分散させて被覆する試みは既にあった。
例えば、特開昭５８−３１０７６号公報に開示されている装置・方法によれば、ＰＶＤ装置内に設置された容器の中に芯粒子粉体の粒子を入れ、容器を電磁気的な方法により振動させ、前記容器内の芯粒子を転動させながらＰＶＤ法により被覆する。又、特開昭６１−３０６６３号公報に開示されている装置によれば、ＰＶＤ装置内に設置された容器の中に芯粒子粉体の粒子を入れ、容器を機械的な方法により振動させ、前記容器内の芯粒子を転動させながらＰＶＤ法により被覆するとされている。しかし、これらの容器の振動により芯粒子粉体の粒子を転動させながら被覆する装置或いは方法では、実際には、微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子である高圧型窒化硼素粉体粒子の凝集体を崩すのに要する凝集力を上回る作用を加えることができないため、この凝集体を崩すことができずむしろ造粒作用が働き、容器内に導入する前以上に、より多く、或いはより大きな凝集体を形成するだけであった。
【０００６】
特開平３−１５３８６４号公報に開示されている装置及び方法は、内面に障壁及び／又は凹凸を備えた回転容器内に粒子を入れ、この回転容器を回転させながら蒸着法により芯粒子表面に被覆を行うことを目的とするものであるが、このような装置或いは方法においては、微粒子の芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子である高圧型窒化硼素粉体粒子の凝集体を崩すのに要する凝集力を上回る作用を加えることができないため、凝集体を壊すことができないばかりか、より多く、或いはより大きな凝集体を形成するだけであった。
特開昭５８−１４１３７５号公報には、反応ガス雰囲気中に置かれた粉体を反応ガスの流れと重力の作用とによって浮遊させて、反応ガスの化学反応により生成される析出物質によって粉体の表面を被覆する装置が開示されている。又、特開平２−４３３７７号公報には、微粒子を減圧下において流動化させながら、熱化学反応処理を行い被覆を行う方法が開示されている。これらの気流による流動層を利用する装置或いは方法では、微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子である高圧型窒化硼素粉体粒子の一個一個を流動化させることが事実上不可能で、高圧型窒化硼素粉体粒子の凝集体を崩せなかった。
【０００７】
特開昭５４−１５３７８９号公報には、金属の蒸気を発生させた真空容器内を粉末材料を落下させ金属を被覆する装置が開示されている。又、特開昭６０−４７００４号公報には真空槽中の高周波プラズマ領域にモノマーガスと粉体粒子を導入し、プラズマ重合により有機物の被覆膜を形成させる方法が開示されている。これらの装置或いは方法の如く、単に導入するだけでは微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子である高圧型窒化硼素粉体粒子の凝集体を壊せなかった。
特開昭６４−８０４３７号公報には、低・高周波合成音波により芯粒子粉体の凝集体を崩して流動化させ被覆する方法が開示されている。しかし、流動層に振動を与えるこの方法では、微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子である高圧型窒化硼素粉体粒子の凝集体を崩せなかった。
【０００８】
特開昭６２−２５０１７２号公報には、前処理として、ジェットミル処理した粉体を、減圧加熱処理室に滞留させ、ここで加熱処理を施した後、粉体フィーダーでスパッタリング室に自然落下で導入し、ターゲットを垂直に設けた円筒状のスパッタリング室に自然落下させて被覆する装置及び方法が開示されている。又特開平２−１５３０６８号公報には、前処理としてジェットミル処理した粉体を、減圧加熱処理室で滞留させ、ここで加熱処理を施した後、粉体フィーダーでスパッタリング室のスパッタリング源を納めた回転容器に粉体状で導入し、容器を回転さた状態でスパッタリングする装置及び方法が開示されている。これらの装置では、ジェットミル処理によりその時だけ粉体は一時的に分散されるが、被覆前の加熱工程で、この粉体を滞留させる構造であり、そのような方法のため、仮にジェットミル処理で一時的に一次粒子状態に分散しても当該加熱工程でのこの粉体の滞留のため再凝集し、結局、被覆工程に導入される時には凝集したままである。
以上のように、これまでのものでは、いずれも微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子である高圧型窒化硼素粉体粒子に被覆する装置或いは方法としての問題解決はなされておらず、そのため、高圧型窒化硼素粉体粒子一個一個に結合材となる物質及び／又は焼結助剤となる物質を被覆形成物質として気相被覆法により均一に被覆を施した被覆された高圧型窒化硼素粉体粒子が作製できなかった。
【０００９】
【発明が解決しようとする課題】
従って、現実に、被覆されるべき高圧型窒化硼素粉体粒子であって、１０μｍ以下の平均粒子径の粒子である、微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子を単一粒子単位で、結合材となる物質及び／又は焼結助剤となる物質を被覆形成物質として被覆した被覆された高圧型窒化硼素粉体粒子による高性能な高圧型窒化硼素焼結体及びその製造方法の解明が強く求められている。
本発明は、微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体粒子である高圧型窒化硼素粉体粒子へ単一粒子単位に、結合材となる物質及び／又は焼結助剤となる物質を被覆した被覆された高圧型窒化硼素粒子による、均一で、緻密で、且つ強固に焼結された、微組織が高度に制御された高性能な高圧型窒化硼素焼結体及びその製造法を提供することを目的とする。
【００１０】
【課題を解決するための手段】
前記課題を解決するために、本発明者が鋭意研究を重ねた結果、微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体が高圧型窒化硼素粉体の粒子である高圧型窒化硼素粉体粒子へ単一粒子単位に結合材となる物質及び／又は焼結助剤となる物質を被覆形成物質として被覆するためには、体積基準頻度分布で平均粒子径が１０μｍ以下の芯粒子粉体の粒子が主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物中の芯粒子粉体の粒子を、分散度βが７０％以上である高い分散状態の被覆空間の被覆開始領域で、被覆を開始しなければならないことを見い出した。
【００１１】
より詳しくは、（Ｉ）高圧型窒化硼素粉体の粒子が主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物の状態に分散させたこの芯粒子粉体の粒子は、滞留させなくとも、時間の経過と共にブラウン凝集、乱流凝集、音波凝集等により再凝集する傾向にあり、一旦再凝集すると、特別に高い分散性能を有する分散処理手段により分散させなければ、再凝集の状態を崩して再分散させることが困難であり、このため、体積基準頻度分布で平均粒子径が１０μｍ以下の芯粒子粉体の粒子が主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物中の芯粒子粉体の粒子を、分散度βが７０％以上である高い分散状態で被覆空間の被覆開始領域に導く必要があること、またそのためには、（II）この芯粒子粉体の粒子からなる凝集体を崩し、且つ主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物中の芯粒子粉体の粒子を高い分散状態に分散させる、一以上からなる特別に高い分散性能を有する分散処理手段群が必要であることを見い出して本発明に至った。
そしてこのようにして得られた被覆された高圧型窒化硼素粉体粒子、又は同粒子を含む混合物を２０００ ＭＰａ以上の超高圧力・高温において焼結することにより、均一で、緻密で、且つ強固に焼結された、微組織が高度に制御された高性能な被覆高圧型窒化硼素焼結体が得られたのである。
【００１２】
即ち、本発明は、高圧型窒化硼素の微粒子からなる芯粒子粉体の粒子、又は主に同微粒子からなる芯粒子粉体の粒子であって、その表面が被覆形成物質で被覆されたものを焼結して高圧型窒化硼素焼結体を製造するに当り、この被覆形成物質で被覆された高圧型窒化硼素粒子は、芯粒子粉体を被覆空間に投入し、気相を経て生成する被覆形成物質前駆体及び／又は気相状態の被覆形成物質前駆体を、芯粒子粉体の粒子に接触及び／又は衝突させて、芯粒子粉体の粒子の表面が被覆形成物質で被覆されたものであって、
（Ａ） 微粒子高分散処理手段群の最終処理手段が、
（ａ） この芯粒子粉体の粒子を気中に分散させる分散手段、および
（ｂ） 芯粒子粉体の粒子を気中に分散させた芯粒子粉体の粒子と気体との混合物において低分散芯粒子粉体部分を分離し、芯粒子粉体の粒子が主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物を選択する高分散芯粒子粉体の粒子・気体混合物選択手段とこの高分散芯粒子粉体の粒子・気体混合物選択手段により選択分離された低分散芯粒子粉体部分を微粒子高分散処理手段群中の分散手段の内の最終分散手段及び／又は最終分散手段以前の処理手段に搬送するフィードバック手段とを備えた高分散芯粒子粉体の粒子・気体混合物選択手段、
から選ばれる微粒子高分散処理手段群により、体積基準頻度分布で平均粒子径が１０μｍ以下の微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子を、気中に分散させて高分散芯粒子粉体の粒子・気体混合物とする分散工程、
（Ｂ） この分散工程で分散させた芯粒子粉体の粒子を、分散度βが７０％以上の分散状態で、被覆空間の被覆開始領域において被覆形成物質前駆体と接触及び／又は衝突させて被覆を開始する被覆工程、
からなる被覆手段によって調製されたものを使用し、
この被覆された高圧型窒化硼素粒子、又は同粒子を含む混合物を２０００MPa以上の圧力、及び高温度において焼結することを特徴とする被覆高圧型窒化硼素焼結体の製造法を提供するものである。
【００１３】
更に本発明は、上記した高圧型窒化硼素焼結体を製造する方法において、被覆形成物質で被覆された高圧型窒化硼素粒子が、
被覆された高圧型窒化硼素粒子の被覆形成物質を介して接触状態で集合塊を形成した被覆された高圧型窒化硼素粒子の集合塊を、解砕及び／又は破砕する被覆された高圧型窒化硼素粒子集合塊の解砕・破砕工程、及び／又は
この被覆高圧型窒化硼素粒子集合塊と一次粒子単位の被覆された高圧型窒化硼素粒子とを選択分離する選択分離工程
を更に経て調製されたものであり、そしてこの被覆された高圧型窒化硼素粒子、又は同粒子を含む混合物を、２０００MPa以上の圧力、及び高温度において焼結する上記焼結体の製造法にも関する。
【００１４】
更に本発明は、上記した高圧型窒化硼素焼結体を製造する方法において、その表面を被覆形成物質で被覆するべき高圧型窒化硼素の微粒子からなる芯粒子粉体の粒子又は主に同粒子からなる芯粒子粉体の粒子が、溶融塩浴を用いる浸漬法により、浸漬法に由来する被覆物質で一層以上被覆された微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子であり、これを被覆形成物質で被覆して得られた被覆された高圧型窒化硼素粒子、又は同粒子を含む混合物を、２０００ ＭＰａ以上の圧力、及び高温度において焼結する上記焼結体の製造法にも関する。
また本発明は、上記した被覆高圧型窒化硼素を（Ａ）高圧型窒化硼素の熱力学的安定領域で、及び／又は（Ｂ）動的及び／又は静的な２０００ ＭＰａ以上の超高圧力・高温下で焼結することにより、焼結体を製造する方法にも関する。
【００１５】
更にまた本発明は、上記した高圧型窒化硼素焼結体を製造する方法において、被覆形成物質で被覆された高圧型窒化硼素粒子が、体積基準頻度分布で平均粒子径が１０μｍ以下の芯粒子粉体を、微粒子高分散処理手段群の最終処理により気中に分散させて高分散芯粒子粉体の粒子・気体混合物とし、その芯粒子粉体の粒子の分散度βを７０％以上とする分散性能を有する微粒子高分散処理手段群による分散工程を設け、微粒子高分散処理手段群により分散させた高分散芯粒子粉体の粒子・気体混合物を被覆工程に直接放出するか、又は分散工程と被覆工程の間に、微粒子高分散処理手段群により分散させた高分散芯粒子粉体の粒子・気体混合物を放出する放出部から、搬送に不可避の、中空部材、中空を形成せしめる部材からなる中間部材、及びパイプから選択される一種類またはそれ以上の部材を介して搬送するか、及び／又は、前記分散性能で気中に分散させた高分散芯粒子粉体の粒子・気体混合物中の粒子の気中分散状態を維持する気中分散維持手段、前記分散性能で気中に分散させた高分散芯粒子粉体の粒子・気体混合物中の粒子の気中分散状態を高める気中分散促進手段、芯粒子粉体の粒子と気体との混合物の内の、低分散芯粒子粉体部分を分離し、芯粒子粉体の粒子が主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物を選択する高分散芯粒子粉体の粒子・気体混合物選択手段の一種またはそれ以上を介して搬送して調製されたものであり、そして、この被覆された高圧型窒化硼素粒子、又は同粒子を含む混合物を、２０００ ＭＰａ以上の圧力、及び高温度において焼結する上記焼結体の製造法にも関する。
【００１６】
更にまた本発明は、上記した高圧型窒化硼素焼結体を製造する方法において、被覆形成物質で被覆された高圧型窒化硼素粒子が、体積基準頻度分布で平均粒子径が１０μｍ以下の芯粒子粉体を、微粒子高分散処理手段群の最終処理により気中に分散させて高分散芯粒子粉体の粒子・気体混合物とし、その芯粒子粉体の粒子の分散度βを７０％以上とする分散性能を有する微粒子高分散処理手段群による分散工程の一部以上と前記被覆工程の一部以上とを、空間を一部以上共有して行うことにより調製されたものであり、そして、この被覆された高圧型窒化硼素粒子、又は同粒子を含む混合物を、２０００MPa以上の圧力、及び高温度において焼結する上記焼結体の製造法にも関する。
【００１７】
更にまた本発明は、上記した高圧型窒化硼素焼結体を製造する方法において、被覆形成物質で被覆された高圧型窒化硼素粒子が、体積基準頻度分布で平均粒子径が１０μｍ以下の芯粒子粉体を、微粒子高分散処理手段群の最終処理により、気中に分散させて高分散芯粒子粉体の粒子・気体混合物とし、その芯粒子粉体の粒子の分散度βを７０％以上とする空間領域の内の、高分散芯粒子粉体の粒子・気体混合物中の芯粒子粉体の粒子のすべての粒子が通過する面を含む空間領域に、被覆空間の被覆開始領域を位置せしめるか、又は体積基準頻度分布で平均粒子径が１０μｍ以下の芯粒子粉体を、微粒子高分散処理手段群の最終処理により気中に分散させて高分散芯粒子粉体の粒子・気体混合物中とし、その芯粒子粉体の粒子の分散度βを７０％以上とする空間領域の内の、回収手段の回収部に回収する全ての粒子が通過する面を含む空間領域に、被覆空間の被覆開始領域を位置せしめることにより調製されたものであり、そしてこの被覆された高圧型窒化硼素粒子、又は同粒子を含む混合物を、２０００ ＭＰａ以上の圧力、及び高温度において焼結する上記焼結体の製造法にも関する。
【００１８】
更にまた本発明は、上記した高圧型窒化硼素焼結体を製造する方法において、被覆形成物質で被覆された高圧型窒化硼素粒子が、粒度分布が、平均粒子径をＤ_Mとしたとき、体積基準頻度分布で(〔Ｄ_M／５，５Ｄ_M〕，≧９０％）である芯粒子粉体に被覆形成物質を被覆して調製されたものであり、そして、この被覆された高圧型窒化硼素粒子、又は同粒子を含む混合物を、２０００MPa以上の圧力、及び高温度において焼結する上記焼結体の製造法にも関する。
そして本発明は、上記した製造方法によって製造される被覆高圧型窒化硼素焼結体にも関するものである。
【００１９】
而して、本発明によれば、高圧型窒化硼素の微粒子からなる芯粒子粉体の粒子又は主に同微粒子からなる芯粒子粉体の粒子であって、その表面が被覆形成物質で被覆されたものを、２０００ ＭＰａ以上の圧力及び高温度において焼結して高圧型窒化硼素粒子の焼結体を製造するに際して、上記した表面が被覆形成物質で被覆された高圧型窒化硼素粒子として、気相法により気相を経て生成する被覆形成物質前駆体及び／又は気相状態の被覆形成物質前駆体と、微粒子高分散処理手段群の最終処理手段により気中に分散させた平均粒子径が１０μｍ以下の微粒子からなる高分散芯粒子粉体の粒子・気体混合物とを、被覆空間の被覆開始領域で、高分散芯粒子粉体の粒子・気体混合物中の芯粒子粉体の粒子の分散度がβ≧７０％である分散状態で合流させ、接触及び／又は衝突させて高圧型窒化硼素粒子の表面を被覆形成物質で被覆したものを用いることにより、これまでに得られなかった高圧型窒化硼素の粒子表面の未焼結部のない、均一で、緻密で、且つ強固に焼結された、高度に制御された微組織を有する高性能な高圧型窒化硼素焼結体を得ることができた。そして、上記した被覆芯粒子の調製に際して、被覆形成物質前駆体は、原子、分子、イオン、クラスター、原子クラスター、分子クラスター、クラスターイオン等からなる気相状態の、域は気相を経て生成したばかりのもので、この高分散状態の芯粒子と接触及び／又は衝突を始めることにより、一次粒子状態の個々の芯粒子の表面に被覆形成物質は強固に結合し、その結果、芯粒子の表面を被覆形成物質により単一粒子単位で被覆を施した被覆された高圧型窒化硼素粒子が製造できるのである。
【００２０】
以下に本発明を詳細に説明する前に、本明細書中に使用する用語をはじめに定義することにし、そして必要によってその用語の具体的内容を説明し、次いで被覆形成物質で被覆された高圧型窒化硼素粒子の調製がどのような技術的手段によって行なわれるものであるのかの説明を行うことにする。
【００２１】
被覆された高圧型窒化硼素粒子
被覆された高圧型窒化硼素粒子とは、被覆が施された下記する高圧型窒化硼素粒子をいう。例えば、具体的には、被覆形成物質が、超微粒子状、島状、連続質状、一様な膜状、突起物状等の一種以上の形態で芯粒子として高圧型窒化硼素粒子に被覆された粒子をいう。
【００２２】
高圧型窒化硼素原料粉体粒子
本発明に係る、高圧型窒化硼素粉体粒子が微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子である高圧型窒化硼素芯粒子の表面に、被覆形成物質を被覆した被覆された高圧型窒化硼素粒子用の高圧型窒化硼素粒子の原料粉体粒子には、人工の高圧型窒化硼素粒子である静的及び／又は動的超高圧合成、及び／又は低圧気相法合成による立方晶型及び／又はウルツ鉱型窒化硼素粒子を用いることができる。
【００２３】
高性能な被覆高圧型窒化硼素焼結体を製造するための高圧型窒化硼素原料粉体粒子としては、その粒子径が１０μｍ以下の高圧型窒化硼素粒子が用いられる。具体的には、高圧型窒化硼素粒子は、平均粒子径Ｄ_Mが１０μｍ以下で体積頻度分布が(〔Ｄ_M／５，５Ｄ_M〕，≧９０％)の高圧型窒化硼素粉体粒子が一般に流通しているのでこれを適用できる。用途に応じて比較的分布の幅の狭い平均粒子径Ｄ_Mが１０μｍ以下で体積基準頻度分布が(〔Ｄ_M／３，３Ｄ_M〕，≧９０％）の高圧型窒化硼素粉体粒子、或は分級等により高圧型窒化硼素粒子の粒子径が管理され更に分布の幅の狭い平均粒子径Ｄ_Mが１０μｍ以下で体積基準頻度分布が（〔Ｄ_M／２，３Ｄ_M／２〕，≧９０％）の高圧型窒化硼素粉体粒子を選択できる。
このような分布の高圧型窒化硼素粒子を原料粉体粒子として適用すると、被覆高圧型窒化硼素焼結体中の高圧型窒化硼素の粒子表面の未焼結部分のない均一で、緻密で且つ強固に焼結された、高度に制御された微組織を有する高性能な被覆高圧型窒化硼素焼結体が製造できる。
本発明の被覆高圧型窒化硼素焼結体は、前記高圧型窒化硼素粉体粒子表面に、被覆形成物質の被覆を施した被覆された高圧型窒化硼素粒子又は同粒子を含む混合物を２０００ ＭＰａ以上の超高圧力・高温下で焼結することにより得られる、高圧型窒化硼素粒子を含む被覆高圧型窒化硼素焼結体でなるものである。
【００２４】
気相被覆法
気相被覆法とは、被覆形成物質の原料が、分子流、イオン流、プラズマ、ガス、蒸気、エアロゾルの一種以上からなる気相状態を少なくとも一度は経て被覆する方法、又は気相状態の被覆形成物質の原料により被覆する方法をいう。
【００２５】
芯粒子
芯粒子とは、被覆を施す対象物となる粒子をいう。これはまた、母材粒子、種粒子或は被覆される粒子ともいう。
この芯粒子は、高圧型窒化硼素粒子、具体的には立方晶窒化硼素粒子及び／又はウルツ鉱型窒化硼素粒子からなる。
【００２６】
芯粒子粉体
芯粒子粉体とは、芯粒子からなる粉体をいう。芯粒子粉体の粒子とは、芯粒子粉体を構成する粒子をいう。本発明で用いる被覆に供する微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子は、平均粒子径が体積基準頻度分布で１０μｍ以下である。
好ましくは、平均粒子径をＤ_Mとしたとき、Ｄ_Mが１０μｍ以下で、粒度分布が体積基準頻度分布で（〔Ｄ_M／５，５Ｄ_M〕，≧９０％）である。このような比較的分布の幅の狭い粉体では、平均粒子径で粉体の分散特性又は凝集特性が特徴付けられ、Ｄ_Mの値に適した条件で微粒子高分散処理手段群を作動させれば分散できる。
平均粒子径が１０μｍ以下の芯粒子粉体の粒子の粒度分布が、幅広い分布又は互いに離れた複数のピークを持つ分布の粉体では、好適には適当な選択分離処理、例えば分級処理を行ってそれぞれ分級された粉体ごとに、被覆処理を施す。これにより、それぞれ分級された粉体ごとに上記条件の下で、被覆空間の被覆開始領域で分散度βが７０％以上の状態で被覆が開始され、芯粒子粉体の粒子一つ一つの粒子に被覆が可能となる。
【００２７】
被覆形成物質
被覆形成物質とは、被覆を施す対象物に被覆を形成する物質をいう。例えば、具体的には、超微粒子状、島状、連続質状、一様な膜状、突起物状等の一種以上からなる形態で芯粒子粉体の粒子に被覆を形成する物質をいう。
特に、被覆形成物質の形態が超微粒子状の場合、超微粒子の粒子径は、例えば０.００５μｍ〜０.５μｍの範囲のものをいう。
この被覆形成物質は、被覆形成物質自体がそのままで被覆を形成するか、又は被覆形成物質と芯粒子の高圧型窒化硼素とが反応して及び／又は高圧型窒化硼素粒子に固溶して及び／又は二種類以上の被覆形成物質同志が反応して及び／又は合金化して及び／又は固溶して被覆を形成するための目的とする無機化合物、合金、金属間化合物等の一種類又はそれ以上を生成し、被覆高圧型窒化硼素粒子の焼結を促進する焼結助剤及び／又は結合材となる単体物質及び／又は化合物及び／又は高圧型窒化硼素粒子の表面改質剤となる単体物質及び／又は化合物から選択される。
【００２８】
すなわち、高圧型窒化硼素粒子の粒界を制御する表面改質剤としても被覆形成物質が選択可能である。必要に応じて例えば、高圧型窒化硼素粒子と結合材及び／又は焼結助剤との化学結合性を高めたり、又は個々の高圧型窒化硼素粒子を任意の物質から隔離させ、これにより高圧型窒化硼素と任意の物質との反応を抑止したり、或は焼結条件が、圧力が２０００ ＭＰａ以上で且つ高圧型窒化硼素が熱力学的準安定な領域の焼結条件を選択する必要がある場合は、グラファイト型相への相転移を抑止することもできる。これにより、結合材及び／又は焼結助剤としての被覆形成物質の選択の幅が飛躍的に大きく広がり好適である。
【００２９】
これらの被覆形成物質は、周期律表１ａ、２ａ、３ａ、４ａ、５ａ、６ａ、７ａ、１ｂ、２ｂ、３ｂ、４ｂ、５ｂ、６ｂ、７ｂ、８族の金属、半導体、半金属、希土類金属、非金属及びその酸化物、窒化物、炭化物、酸窒化物、酸炭化物、炭窒化物、酸炭窒化物、硼化物、珪化物の一種類又はそれ以上、例えばＡｌ、Ｂ、Ｓｉ、Ｆｅ、Ｎｉ、Ｃｏ、Ｔｉ、Ｎｂ、Ｖ、Ｚｒ、Ｈｆ、Ｔａ、Ｗ、Ｒｅ、Ｃｒ、Ｃｕ、Ｍｏ、Ｙ、Ｌａ、ＴｉＡｌ、Ｔｉ₃Ａｌ、ＴｉＡｌ₃、ＴｉＮｉ、ＮｉＡｌ、Ｎｉ₃Ａｌ、ＳｉＣ、ＴｉＣ、ＺｒＣ、Ｂ₄Ｃ、ＷＣ、Ｗ₂Ｃ、ＨｆＣ、ＶＣ、ＴａＣ、Ｔａ₂Ｃ、ＮｂＣ、Ｍｏ₂Ｃ、Ｃｒ₃Ｃ₂、Ｓｉ₃Ｎ₄、ＴｉＮ、ＺｒＮ、Ｓｉ₂Ｎ₂Ｏ、ＡｌＮ、ＨｆＮ、ＶｘＮ（ｘ＝１〜３）、ＮｂＮ、ＴａＮ、Ｔａ₂Ｎ、ＴｉＢ、ＴｉＢ₂、ＺｒＢ₂、ＶＢ、Ｖ₃Ｂ₂、ＶＢ₂、ＮｂＢ、ＮｂＢ₂、ＴａＢ、ＴａＢ₂、ＭｏＢ、ＭｏＢ₂、ＭｏＢ₄、Ｍｏ₂Ｂ、ＷＢ、Ｗ₂Ｂ、Ｗ₂Ｂ₅、ＬａＢ₆、Ｂ₁₃Ｐ₂、ＭｏＳｉ₂、ＢＰ、Ａｌ₂Ｏ₃、ＺｒＯ₂、ＭｇＡｌ₂Ｏ₄（スピネル）、Ａｌ₂ＳｉＯ₅（ムライト）の一種類又はそれ以上を含む物質であることができる。
この被覆形成物質の被覆による添加量は、微量から多量までの任意の量を選択できる。
【００３０】
被覆空間に投入の定義
被覆空間に投入とは、例えば、自由落下等の落下によって芯粒子粉体を被覆空間に導入することをいう。搬送ガスにより投入する場合には、芯粒子粉体を芯粒子粉体の粒子・気体混合物の流れの方向に乗せて導入したり、気体に乗せて流れの方向へ、或いは気体に乗り方向が変えられて導入することをいう。または、搬送ガスの作用を受けて導入することをもいう。例えば、搬送ガスの波動現象、具体的には非線系波動によって導入することをもいう。或いは、ガス中の音波、超音波、磁場、電子線等によって被覆空間に導入することをもいう。また、外場、例えば電場、磁場、電子線等により導入することをもいう。具体的には、電場、磁場、電子線等により粉体粒子を帯電させ、または帯磁させ引力又は斥力により被覆空間に導入することをもいう。また、ガスの背圧や減圧によって吸い込まれ、導入することも含む。
【００３１】
被覆空間
被覆空間とは、被覆形成物質の原料から気相を経て生成する被覆形成物質前駆体及び／又は気相状態の被覆形成物質前駆体と芯粒子粉体の粒子が接触及び／又は衝突する空間をいう。あるいは、芯粒子粉体の粒子の表面を被覆形成物質で被覆する空間領域をいう。
被覆室
被覆室とは、被覆空間を一部以上有する室をいう。より具体的には、被覆室とは、被覆空間を含む仕切られた、又は略仕切られた（略閉じた、半閉じた）室であって、被覆空間を一部以上含む室である。
気中
気中とは、真空又は気相状態の空間内をいう。ここで、本発明において、気相状態とは、分子流、イオン流、プラズマ、ガス、蒸気などの状態をいう。真空とは、技術的には、減圧状態をさす。どんな減圧下でも、厳密にはガス、分子、原子、イオン等が含まれる。
【００３２】
被覆形成物質前駆体
被覆形成物質前駆体とは、被覆形成物質の前駆体である。より詳しくは、気相状態の被覆形成物質の原料がそのまま、又は被覆形成物質の原料から気相を経て形成及び／又は合成され、被覆を施す対象物となる粒子である芯粒子に被覆を形成する直前までの物質をいう。被覆形成物質前駆体は、被覆形成物質の原料から、気相を経て形成及び／又は合成する限り、状態の制限はない。被覆形成物質の原料が気相の場合、この原料が被覆形成物質前駆体にもなりうる。被覆形成物質前駆体そのものが気相であってもよい。また、被覆形成物質前駆体が反応性物質の場合は、反応前でも良く、反応中でもよく、反応後でもよい。被覆形成物質前駆体の具体例としては、イオン、原子、分子、クラスター、原子クラスター、分子クラスター、クラスターイオン、超微粒子、ガス、蒸気、エアロゾル等が挙げられる。
被覆形成物質の原料
被覆形成物質の原料とは、気相を経て被覆を形成する物質となる原料物質をいう。被覆形成物質の原料の形態の具体例として、塊状の固体、粉体粒子、気体、液体等が挙げられる。
【００３３】
分散度β
分散度βとは、粉体分散装置の分散性能を評価する指数として増田、後藤氏らが提案（化学工学、第２２回、秋季大会研究発表講演要旨集、Ｐ３４９（１９８９）参照）したように、全粒子の重量に対する、見かけの一次粒子状態の粒子の重量の割合と定義する。ここで、見かけの一次粒子状態の粒子とは、任意の分散状態の粉体粒子の質量基準の頻度分布ｆ_m2と完全分散されている粉体粒子の質量基準の頻度分布ｆ_m1のオーバーラップしている部分の割合を示し、次の式のβで表される。
【００３４】
【数１】

上式において、粒子径の単位（μｍ）は規定されるものではない。
上式は質量基準で表した粒度分布を基にして分散度を評価しているが、本来分散度は体積基準で表した粒度分布を基にして評価されるべきものである。粉体粒子密度が同じである場合には質量基準で表した粒度分布と体積基準で表した粒度分布は同じになる。そこで実用上測定が容易な質量基準の粒度分布を測定し、それを体積基準の粒度分布として用いている。従って本来の分散度βは次の式及び図１(ａ)の斜線部分の面積で表される。
【００３５】
【数２】

上式において、粒子径の単位（μｍ）は規定されるものではない。
そして芯粒子粉体の分布及び平均粒子径は、特に断らない限り基本的には体積基準を用いることとする。
【００３６】
体積基準頻度分布
体積基準頻度分布とは、粒子径の分布をある粒子径に含まれる体積割合をもって表したものをいう。
（〔Ｄ₁,Ｄ₂〕，≧９０％）の定義
（〔Ｄ₁,Ｄ₂〕，≧９０％）分布とは、Ｄ₁、Ｄ₂を粒子径、但しＤ₁＜Ｄ₂とするとき、Ｄ₁以上でＤ₂以下の粒子が体積で９０％以上含まれる分布を表し、図１(ｂ)のように斜線の部分の割合が９０％以上である粒子からなる粉体を表す。
【００３７】
体積基準頻度分布（〔Ｄ_M／５，５Ｄ_M〕，≧９０％）の定義
粒度分布が、体積基準頻度分布で（〔Ｄ_M／５，５Ｄ_M〕，≧９０％）分布とは、Ｄ_Mを体積基準の平均粒子径とするとき、Ｄ_Mの１／５倍の粒子径以上、Ｄ_Mの５倍の粒子径以下の粒子を体積で９０％以上含む分布を表す。例えば、平均粒子径Ｄ_Mが５μｍで体積基準頻度分布が（〔Ｄ_M／５，５Ｄ_M〕，≧９０％）とは、体積基準の平均粒子径が５μｍで、１μｍ以上且つ２５μｍ以下の粒子径の粒子が体積で９０％以上含まれるような分布を表す。ここで、体積基準の平均粒子径Ｄ_Mは、
【数３】

又は技術的には、ある粒子径間隔をＤ_i±△Ｄ_i／２（△Ｄ_iは区分の幅）内にある粒子群の体積をｖ_iとすると、
Ｄ_M＝Σ(ｖ_iＤ_i)／Σｖ_i
と表される。
【００３８】
被覆開始領域
微粒子高分散処理手段群の最終処理後、初めて被覆が開始される領域を被覆開始領域という。従って、微粒子高分散処理手段群の最終処理以前では、初めて被覆が開始される領域でも、ここでいう被覆開始領域ではない。
【００３９】
被覆開始領域での分散度β
本発明では、体積基準頻度分布で平均粒子径が１０μｍ以下の芯粒子粉体を、微粒子高分散処理手段群の最終処理により気中に分散させて高分散芯粒子粉体の粒子・気体混合物とし、その芯粒子粉体の粒子の分散度βを７０％以上とした領域に被覆空間の被覆開始領域を位置せしめる被覆室を設ける。前記、被覆空間の被覆開始領域における分散度であれば、体積基準頻度分布で平均粒子径が１０μｍ以下の微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子を、実質的に粒子一個一個の単位に気中に分散して被覆に供することができ、被覆空間の被覆開始領域を通過する全ての芯粒子粉体の粒子の表面の少なくとも一部と、被覆形成物質前駆体とは接触及び／又は衝突するため、必ず粒子一個一個の単位に被覆形成物質を付けることができる。
好適には、被覆空間の被覆開始領域において、体積基準頻度分布で平均粒子径が１０μｍ以下の芯粒子粉体を、微粒子高分散処理手段群の最終の分散処理により気中に分散させて高分散芯粒子粉体の粒子・気体混合物とし、その芯粒子粉体の粒子の分散度βを８０％以上とする。この被覆空間の被覆開始領域での分散度であれば、芯粒子粉体の粒子が体積基準頻度分布で平均粒子径が１０μｍ以下の微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子に対して事実上芯粒子同士による閉ざされた部分がなく、一個一個の粒子の表面のいたるところに被覆形成物質前駆体を接触及び／又は衝突させることが可能であり、一個一個の粒子表面にほぼ一様に被覆できる。
【００４０】
より好適には、被覆空間の被覆開始領域において、体積基準頻度分布で平均粒子径が１０μｍ以下の芯粒子粉体を、微粒子高分散処理手段群の最終の分散処理により気中に分散させて高分散芯粒子粉体の粒子・気体混合物とし、その芯粒子粉体の粒子の分散度βを９０％以上とする。この被覆空間の被覆開始領域の分散度であれば、芯粒子粉体の粒子が体積基準頻度分布で平均粒子径が１０μｍ以下の微粒子の芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子であっても事実上凝集しておらず、一個一個の粒子の表面全てに事実上一様に被覆できる。
特に、処理能率が低くてもよいから、高品位な被覆を行いたいときは、分散度は、９５％以上がより好ましい。この場合、微量の芯粒子粉体の粒子を処理して、完全分散の芯粒子粉体の粒子の気中個数濃度を低くすることにより可能となる。これにより、完全に一個一個の粒子の全表面に一様に被覆できる。
【００４１】
微粒子高分散処理手段群
微粒子高分散処理手段群とは、
（Ａ） 少なくとも分散手段を１以上有し、
（Ｂ） 最終の処理手段として、
（ａ） 芯粒子粉体の粒子を気中に分散させる分散手段、又は
（ｂ） 芯粒子粉体の粒子を気中に分散させた芯粒子粉体の粒子と気体との混合物において低分散芯粒子粉体部分を分離し、芯粒子粉体の粒子が主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物を選択する高分散芯粒子粉体の粒子・気体混合物選択手段とこの高分散芯粒子粉体の粒子・気体混合物選択手段により分離された低分散芯粒子粉体部分をこの微粒子高分散処理手段群中の分散手段の内の最終分散手段及び／又は最終分散手段以前の処理手段に搬送するフィードバック手段とを備えた高分散芯粒子粉体の粒子・気体混合物選択手段、
を有するものである。
好適には、体積基準頻度分布で平均粒子径が１０μｍ以下の芯粒子粉体を微粒子高分散処理手段群の最終処理により気中に分散させて高分散芯粒子粉体の粒子・気体混合物とし、その芯粒子粉体の粒子の分散度βを７０％以上とする分散性能を有するものである。
前記被覆開始領域における種々の分散度、例えばβ≧８０％、９０％、９５％に対応してそれらと同等以上の分散性能の微粒子高分散処理手段群を設けることにより、被覆開始領域において、各分散度に応じた高品位な被覆を施すことができる。
【００４２】
最終処理手段
微粒子高分散処理手段群の最終の処理手段が分散手段の場合、この分散処理手段を微粒子高分散処理手段群の最終処理手段という。又、微粒子高分散処理手段群の最終の処理手段が、微粒子高分散処理手段の最終の分散手段へ、高分散芯粒子粉体の粒子・気体混合物選択処理工程時に於いて低分散状態であったために選択分離された部分を搬送するフィードバック手段を備えた高分散芯粒子粉体の粒子・気体混合物選択手段、又は最終の分散手段より前の処理手段に、高分散芯粒子粉体の粒子・気体混合物選択処理工程時に於いて低分散状態であったために選択分離された部分を搬送するフィードバック手段を備えた高分散芯粒子粉体の粒子・気体混合物選択手段の場合、この高分散芯粒子粉体の粒子・気体混合物選択手段を微粒子高分散処理手段群の最終処理手段という。
尚、微粒子高分散処理手段群の最終処理手段であるフィードバック手段を備えた高分散芯粒子粉体の粒子・気体混合物選択手段より前に設ける（例えば、このフィードバック手段を備えた高分散芯粒子粉体の粒子・気体混合物選択手段と最終分散手段の間、或いは最終分散手段より前）高分散芯粒子粉体の粒子・気体混合物選択手段は、フィードバック手段の有無にかかわらず微粒子高分散処理手段群の構成要素である。
【００４３】
分散手段
微粒子を分散するために用いる手段を分散手段という。この分散手段は少しでも或いは僅かでも分散効果を有するものは分散手段として使用可能であり、これを分散手段とする。例えば、一般に供給手段として用いる空気輸送用のロータリーフィーダーやインジェクションフィーダー（粉体工学会編：“粉体工学便覧”、日刊工業新聞社（１９８６）Ｐ５６８、Ｐ５７１）は、分散効果も有するので、分散目的の手段として使用する場合は分散手段である。後述の分散維持・促進手段も分散目的で（βを高める目的で）使用する場合は分散手段となる。そしてこの分散手段は単一の装置、機器である場合も、複合された装置、機器である場合もあり、これらを総称して微粒子高分散処理手段群と呼ぶ。
この微粒子高分散処理手段群は、芯粒子粉体の粒子の加速及び／又は速度勾配に置く気流による分散、芯粒子粉体の粒子の静止障害物及び／又は回転体である障害物への衝突による分散、芯粒子粉体の粒子の流動層及び／又は脈流及び／又は回転ドラム及び／又は振動及び／又は掻取りからなる機械的解砕による分散等の選択された一種類以上の分散の機構を備えたものをいう。
【００４４】
具体的には、微粒子高分散処理手段群は、エジェクタ型分散機、ベンチュリ型分散機、細管、撹拌機、気流中の障害物を利用した分散機、ジェットの吹付けを利用した分散機、螺旋管、回転羽根を利用した分散機、回転するピンを利用した分散機（ケージミル）、流動層型分散機、脈流を利用した分散機、回転ドラムを利用した分散機、振動を利用した分散機、振動ふるい、スクレーパによる掻き取りを利用した分散機、SAEI、Gonell式分散機、中条式分散機、Roller式分散機、オリフィス型分散機、B.M式分散機、Timbrell式分散機、Wright式分散機等の選択された一種以上からなる分散手段を備えたものである（粉体工学会編：“粉体工学便覧”、日刊工業新聞社（１９８６）Ｐ４３０）。
【００４５】
また、特開昭５６−１３３６号に記載の撹拌羽根を利用した分散機、特開昭５８−１６３４５４号に記載の高速気流と分散ノズルを利用した分散機、特開昭５９−１９９０２７号に記載の回転羽根による分散作用とプラズマイオンによる分散作用を利用した分散機、特開昭５９−２０７３１９号に記載のプラズマイオンによる分散作用を利用した分散機、特開昭５９−２１６６１６号に記載のエジェクタとプラズマイオンによる分散作用を利用した分散機、特開昭５９−２２５７２８号に記載のエジェクタとイオン流の分散作用を利用した分散機、特開昭５９−１８３８４５号に記載のプラズマイオンの分散作用を利用した分散機、特開昭６３−１６６４２１号に記載の分散羽根と圧力気体による分散作用を利用した分散機、特開昭６２−１７６５２７号に記載のライン状又はリング状スリット型噴出口を用いた分散機、特開昭６３−２２１８２９号に記載の網状羽根を利用した分散機、特開昭６３−１６２９号に記載の噴射ノズルからの高速気流による分散作用を利用した分散機、実開昭６３−９２１８号に記載の多数の細孔を利用した分散機、実開昭６２−１５６８５４号に記載のエジェクタ型分散機、実開昭６３−６０３４号に記載の細孔とオリフィスを利用した分散機等の公報に記載のものも使用可能である。
微粒子高分散処理手段群に好適な分散手段として、特願昭６３−３１１３５８号、特願平１−７１０７１号、特願平２−２１８５３７号等に記載の装置が挙げられる。
【００４６】
高分散芯粒子粉体の粒子・気体混合物選択手段
高分散芯粒子粉体の粒子・気体混合物選択手段とは、芯粒子粉体の粒子・気体混合物から、低分散芯粒子粉体の粒子・気体混合物を分離し、主に単一粒子状態の粒子を含む高分散芯粒子粉体の粒子・気体混合物を選択する手段をいう。一次粒子の集合体である凝集粒子は、見かけの粒子径が一次粒子の粒子径に比べ大きくなることから、例えば乾式分級手段により分離が可能である。この高分散芯粒子粉体の粒子・気体混合物選択手段の例としては、重力を利用した分級手段、慣性力を利用した分級手段、遠心力を利用した分級手段、静電気を利用した分級手段、流動層を利用した分級手段等から一種以上選択された乾式分級手段が挙げられる。
高分散芯粒子粉体の粒子・気体混合物選択手段の例としては、重力分級機、慣性分級機、遠心分級機、サイクロン、エアセパレータ、ミクロンセパレータ、ミクロプレックス、ムルチプレックス、ジグザグ分級機、アキュカット、コニカルセパレータ、ターボクラシファイア、スーパセパレータ、ディスパージョンセパレータ、エルボジェット、流動層分級機、バーチュアルインパクタ、O-Sepa、ふるい、バイブレーティングスクリーン、シフタ（粉体工学会編：“粉体工学便覧”日刊工業新聞社、Ｐ５１４（１９８６））等が挙げられる。
【００４７】
芯粒子粉体の粒子・気体混合物
芯粒子粉体の粒子・気体混合物とは、(ａ)芯粒子粉体の粒子が気中に一様に浮遊した均質流れ（一様な浮遊流れ）、(ｂ)芯粒子粉体の粒子が気中のある領域で非一様な分布を示す不均質流れ（非均質浮遊流れ）、(ｃ)芯粒子粉体の粒子の摺動層を伴う流れ（摺動流れ）、又は(ｄ)芯粒子粉体の粒子の静止層を伴う流れをいう。
【００４８】
低分散芯粒子粉体の粒子・気体混合物
低分散芯粒子粉体の粒子・気体混合物とは、芯粒子粉体の粒子・気体混合物の内、芯粒子粉体の粒子が主に単一粒子状態以外の状態で気中に存在する芯粒子粉体の粒子・気体混合物をいう。
【００４９】
高分散芯粒子粉体の粒子・気体混合物
高分散芯粒子粉体の粒子・気体混合物とは、芯粒子粉体の粒子が主に単一粒子状態で気中に存在する芯粒子粉体の粒子・気体混合物をいう。高分散芯粒子粉体の粒子・気体混合物は、極めて高分散であっても、実際には凝集粒子を含む。低分散芯粒子粉体の粒子・気体混合物は、実際には、凝集していない単粒子を含み、選択分離して低分散芯粒子粉体の粒子・気体混合物と高分散芯粒子粉体の粒子・気体混合物に分けられる。低分散芯粒子粉体の粒子・気体混合物は、凝集粒子の選択分離及び／又は再分散により、高分散芯粒子粉体の粒子・気体混合物となる。
【００５０】
回収手段
被覆空間で被覆した被覆粒子を取り出す手段を回収手段という。回収手段の内で回収処理の行われる部分を回収部という。被覆空間の被覆開始領域を通過して被覆した被覆粒子は、気中から直接取り出して回収するか、又は気中から取り出して一時的に蓄えてから回収するか、又は、気体と共に回収される。
回収手段の回収部としては、隔壁（障害物）を利用した回収手段の回収部、重力を利用した回収手段の回収部、慣性力を利用した回収手段の回収部、遠心力を利用した回収手段の回収部、帯電による引力を利用した回収手段の回収部、熱泳動力を利用した回収手段の回収部、ブラウン拡散を利用した回収手段の回収部、ガスの背圧や減圧等による吸引力を利用した回収手段の回収部等が利用可能である。
回収手段の回収部の好適な例として、重力集塵機、慣性集塵機、遠心力集塵機、濾過集塵機、電気集塵機、洗浄集塵機、粒子充填層、サイクロン、バグフィルター、セラミックスフィルター、スクラバー等が挙げられる。
【００５１】
次に、本発明で用いる被覆された高圧型窒化硼素粒子を調製する場合に採用される微粒子高分散処理手段群を添付の図面に基づいて説明することにする。
【００５２】
微粒子高分散処理手段群の図の説明
図２(ａ)は被覆された高圧型窒化硼素粒子を調製する際の微粒子高分散処理手段群の基本的な構成の一例を表すブロック図である。芯粒子粉体の粒子を分散させる最終の分散手段Ａ、最終の分散手段以前の分散処理手段群の構成要素ｄで構成されている。εは、芯粒子粉体の粒子の内、主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物である。構成要素ｄとしては、分散手段、供給手段、高分散芯粒子粉体の粒子・気体混合物選択手段等任意の処理手段を単独又は組み合わせて使用できる。構成要素ｄは、必ずしも設けなくとも良い。
微粒子高分散処理手段群は、好適には最終の処理手段である分散手段Ａの処理後、体積基準頻度分布で平均粒子径が１０μｍ以下の芯粒子粉体に対し、分散度が分散度βで７０％以上を実現できる構成のものである。
【００５３】
図２(ｂ)は、被覆された高圧型窒化硼素粒子を調製する際の微粒子高分散処理手段群の基本的な構成の第二の例を表すブロック図である。芯粒子粉体の粒子を分散させる最終の分散手段Ａ、最終の分散手段Ａへ芯粒子粉体の粒子が、主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物、以外の低分散芯粒子粉体の粒子・気体混合物ηをフィードバックさせるフィードバック手段Ｃを備えた最終の高分散芯粒子粉体の粒子・気体混合物選択手段Ｂ、最終の分散手段以前の分散処理手段群の構成要素ｄ、最終分散手段と最終選択手段の間の微粒子高分散処理手段群の構成要素ｅで構成されている。εは、芯粒子粉体の粒子の内、主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物である。構成要素ｄとしては、分散手段、供給手段、選択手段等任意の処理手段を単独又は組み合わせて使用できる。構成要素ｅとしては、分散手段以外の処理手段、例えば供給手段、選択手段等任意の処理手段を単独又は組み合わせて使用できる。構成要素ｄ及びｅは、必ずしも設けなくとも良い。微粒子高分散処理手段群は、好適には最終の処理手段である選択手段Ｂによる処理後、前記分布の芯粒子粉体に対し分散度が分散度βで７０％以上を実現できる構成である。
【００５４】
図２(ｃ)は、被覆された高圧型窒化硼素粒子を調製する際の微粒子高分散処理手段群の基本的な構成の第三の例を表すブロック図である。芯粒子粉体の粒子を分散させる最終の分散手段Ａ、最終の分散手段Ａより前の処理手段へ芯粒子粉体の粒子が、主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物、以外の低分散芯粒子粉体の粒子・気体混合物ηをフィードバックさせるフィードバック手段Ｃを備えた高分散芯粒子粉体の粒子・気体混合物選択手段Ｂ、最終の分散手段以前の微粒子高分散処理手段群の構成要素ｄ、最終の分散手段と最後の選択手段の間の微粒子高分散処理手段群の構成要素ｅで構成されている。εは、芯粒子粉体の粒子の内、主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物である。構成要素ｄとしては、分散手段、供給手段、選択手段等任意の処理手段を単独又は組み合わせて使用できる。構成要素ｄとしては、分散手段以外の処理手段、例えば供給手段、選択手段等任意の処理手段を単独又は組み合わせて使用できる。構成要素ｄ及びｅは、必ずしも設けなくとも良い。微粒子高分散処理手段群は、好適には最終の処理手段である選択手段Ｂによる処理後、前記分布の芯粒子粉体に対し分散度が分散度βで７０％以上を実現できる構成である。
【００５５】
なお、以上のような構成であるから、供給槽、芯粒子生成手段等の粉体の供給源も本微粒子高分散処理手段群の構成に含めてもよい。例えば図２(ｃ)の場合、フィードバック手段Ｃのフィードバック先を供給槽とする構成も高分散処理手段群の構成として良いことは言うまでもない。又、微粒子高分散処理手段群の分散工程の前に、芯粒子粉体の粒子を解砕及び／又は粉砕する解砕工程を入れても良いことは言うまでもない。
【００５６】
上記した微粒子高分散処理手段群の基本的な構成の具体的な代表例をより詳細にしたブロック図に基づいて更に詳しく説明することにする。
構成１
図３(ａ)は、被覆された高圧型窒化硼素粒子を調製する際の微粒子高分散処理手段群の第１の構成を説明するブロック図であって図２(ａ)に対応するものである。本例は、被覆される芯粒子粉体を供給する供給槽１００、被覆される芯粒子粉体を分散させる最終分散手段Ａから構成されている。εは、芯粒子粉体の粒子の内、主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物である。
【００５７】
構成２
図３(ｂ)は、被覆された高圧型窒化硼素粒子を調製する際の微粒子高分散処理手段群の第２の構成を説明するブロック図であって図２(ａ)に対応するものである。本例は、被覆される芯粒子粉体を供給する供給槽１００、被覆される芯粒子粉体を分散させる分散手段ａ、被覆される芯粒子粉体を分散させる最終分散手段Ａから構成されている。εは、芯粒子粉体の粒子の内、主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物である。
【００５８】
構成３
図３(ｃ)は、被覆された高圧型窒化硼素粒子を調製する際の微粒子高分散処理手段群の第３の構成を説明するブロック図であって図２(ａ)に対応するものである。本例は、被覆される芯粒子粉体を供給する供給槽１００、被覆される芯粒子粉体を分散させる分散手段ａ、分散手段ａで分散させた芯粒子粉体の粒子・気体混合物のうちから主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物、以外の低分散芯粒子粉体の粒子・気体混合物ηを分散手段ａへフィードバックさせるフィードバック手段Ｃ、主に高分散芯粒子粉体の粒子・気体混合物を最終の分散手段Ａへ導入する高分散芯粒子粉体の粒子・気体混合物選択手段ｂ、被覆される芯粒子粉体を分散させる最終分散手段Ａ、から構成されている。εは、芯粒子粉体の粒子の内、主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物である。
【００５９】
構成４
図３(ｄ)は、被覆された高圧型窒化硼素粒子を調製する際の微粒子高分散処理手段群の第４の構成を説明するブロック図であって図２(ｂ)に対応するものである。本例は、被覆される芯粒子粉体を供給する供給槽１００、被覆される芯粒子粉体を分散させる最終分散手段Ａ、最終分散手段Ａで分散させた芯粒子粉体の粒子・気体混合物のうちから主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物、以外の低分散芯粒子粉体の粒子・気体混合物ηを分散手段Ａへフィードバックするフィードバック手段Ｃ、高分散芯粒子粉体の粒子・気体混合物を放出する最終の高分散芯粒子粉体の粒子・気体混合物選択手段Ｂから構成されている。εは、芯粒子粉体の粒子の内、主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物である。
【００６０】
構成５
図３(ｅ)は、被覆された高圧型窒化硼素粒子を調製する際の微粒子高分散処理手段群の第５の構成を説明するブロック図であって図２(ｂ)に対応するものである。本例は、被覆される芯粒子粉体を供給する供給槽１００、被覆される芯粒子粉体を分散させる分散手段ａ、被覆される芯粒子粉体を分散させる最終分散手段Ａ、最終分散手段Ａで分散させた芯粒子粉体の粒子・気体混合物のうちから主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物、以外の低分散芯粒子粉体の粒子・気体混合物ηを分散手段Ａへフィードバックするフィードバック手段Ｃ、高分散芯粒子粉体の粒子・気体混合物を放出する最終の高分散芯粒子粉体の粒子・気体混合物選択手段Ｂから構成されている。εは、芯粒子粉体の粒子の内、主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物である。
【００６１】
構成６
図３(ｆ)は、被覆された高圧型窒化硼素粒子を調製する際の微粒子高分散処理手段群の第６の構成を説明するブロック図であって図２(ｂ)に対応するものである。本例は、被覆される芯粒子粉体を供給する供給槽１００、芯粒子粉体の粒子・気体混合物のうちから主に低分散芯粒子粉体の粒子・気体混合物を取り除き、主に高分散芯粒子粉体の粒子・気体混合物を分散手段Ａへ導入する高分散芯粒子粉体の粒子・気体混合物選択手段ｂ、選択分離された芯粒子粉体の粒子を分散させる最終分散手段Ａ、最終分散手段Ａで分散させた芯粒子粉体の粒子・気体混合物のうちから主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物、以外の低分散芯粒子粉体の粒子・気体混合物ηを分散手段Ａへフィードバックさせるフィードバック手段Ｃ、高分散芯粒子粉体の粒子・気体混合物を放出する最終の高分散芯粒子粉体の粒子・気体混合物選択手段Ｂから構成されている。εは、芯粒子粉体の粒子の内、主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物である。
【００６２】
構成７
図３(ｇ)は、被覆された高圧型窒化硼素粒子を調製する際の微粒子高分散処理手段群の第７の構成を説明するブロック図であって図２(ｃ)に対応するものである。本例は、被覆される芯粒子粉体を供給する供給槽１００、被覆される芯粒子粉体を分散させる分散手段ａ、被覆される芯粒子粉体を分散させる最終分散手段Ａ、最終分散手段Ａで分散させた芯粒子粉体の粒子・気体混合物のうちから主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物、以外の低分散芯粒子粉体の粒子・気体混合物ηを分散手段ａへフィードバックするフィードバック手段Ｃ、高分散芯粒子粉体の粒子・気体混合物を放出する最終の高分散芯粒子粉体の粒子・気体混合物選択手段Ｂから構成されている。εは、芯粒子粉体の粒子の内、主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物である。
【００６３】
このようにして達成された微粒子の高分散状態を維持するために、気中分散維持手段を微粒子高分散処理手段群と被覆室の間に付加することもできる。ここでいう気中分散維持手段とは、気中に分散担持された芯粒子粉体の粒子の再凝集を防止して分散度βを維持する手段をいう。又、このようにして達成された芯粒子の高分散状態を促進するために、気中分散促進手段を微粒子高分散処理手段群と被覆室の間に付加することもできる。ここでいう気中分散促進手段とは、気中に分散担持された芯粒子粉体の粒子のうち主に再凝集した粒子の再分散を促進し、分散状態の低下を鈍らせたり、一旦低下した分散状態を元の高分散の状態まで回復するように再分散を促す手段をいう。
気中分散維持手段又は気中分散促進手段の好適な例としては、パイプ振動装置、パイプ加熱装置、プラズマ発生装置、荷電装置等が挙げられる。
【００６４】
パイプ振動装置は、発振器を設置したパイプの振動により、気中に分散している粒子に分散機とは言えない振動を与えることで、再凝集を抑制し高分散状態を維持する手段又は再凝集した粒子の分散を促進する手段である。
パイプ加熱装置は、加熱したパイプにより搬送気体の外側から熱を加えて搬送気体を膨張させ、分散機とは言えないほどに流速を加速して再凝集を抑制し、再凝集した粒子の分散を促進する手段である。
【００６５】
プラズマ発生装置は、芯粒子粉体を分散担持している気中にプラズマを発生させ、そのプラズマイオンと芯粒子との衝突により、再凝集を抑制し高分散状態を維持する手段又は再凝集した粒子の分散を促進する手段である。
荷電装置は、芯粒子粉体を分散担持している気中に、コロナ放電、電子ビーム、放射線等の方法で単極イオンを発生させ、単極イオン雰囲気中を通過させることで粒子を単極に帯電させ、静電気の斥力により再凝集を抑制し高分散状態を維持する手段又は再凝集した粒子の分散を促進する手段である。
【００６６】
このようにして形成された微粒子の高分散状態の芯粒子粉体は粒子の表面を被覆形成物質で被覆するために被覆室に送られる。この被覆室には被覆開始領域を含む被覆空間が設けられている。
微粒子高分散処理手段群と被覆室とは直結することが望ましいが、搬送に不可避の中空部材及び／又はパイプを使って接続しても良い。この場合にも、被覆開始領域でのβ≧７０％を実現することが不可欠である。
微粒子高分散処理手段群と被覆室を別々に置いてその間を連結する場合は、芯粒子粉体をその分散状態のまま被覆室へ導入してやれば良い。そのためには、この間に芯粒子粉体の分散状態を維持するための装置である気中分散維持手段及び／又は分散状態を高めるための装置である気中分散促進手段及び／又は芯粒子粉体の粒子・気体混合物から、低分散芯粒子粉体部分を分離し、主に単一粒子状態の粒子を含む高分散芯粒子粉体の粒子・気体混合物を選択する高分散芯粒子粉体の粒子・気体混合物選択手段を設けることもできる。
【００６７】
又、被覆された高圧型窒化硼素粒子を調製するに際して、微粒子高分散処理手段群が、(１)被覆室、又は(２)被覆空間、又は(３)被覆開始領域と一部以上空間を共有することもできる。
例えば、微粒子高分散手段群中の分散空間と被覆室とを、又は微粒子高分散手段群中の分散空間と被覆開始領域を有する被覆空間とを、又は微粒子高分散手段群中の分散空間と被覆開始領域とを、空間的に共有することもできる。
ここで被覆開始領域とは、β≧７０％の分散状態で搬送された高分散状態の芯粒子粉体に気相を経て生成する被覆形成物質前駆体及び／又は気相状態の被覆形成物質前駆体が接触及び／又は衝突し、被覆を開始する領域を指し、次の図４(ａ)〜(ｅ)で示される態様が考慮される。
すなわち、図４(ａ)〜(ｅ)において被覆開始領域は２で示される領域である。
【００６８】
図４(ａ)において粉体に対してβ≧７０％の分散状態で被覆を始める被覆空間の被覆開始領域２を微粒子高分散処理手段群又は微粒子高分散処理手段群の一部。好適には微粒子高分散処理手段群の放出部１を覆って設ける。
図４(ｂ)において微粒子高分散処理手段群又は微粒子高分散処理手段群の放出部１から放出される芯粒子粉体の粒子４が全て通る前記β≧７０％の分散状態で被覆を始める被覆空間の被覆開始領域２を設ける。
上記の構成により、全ての芯粒子粉体の粒子はβ≧７０％の分散状態で被覆が始められる。
図４(ｃ)において微粒子高分散処理手段群又は微粒子高分散処理手段群の放出部１から放出される芯粒子粉体の粒子４の内、回収部５に入る粒子が必ず通過する前記β≧７０％の分散状態で被覆を始める被覆空間の被覆開始領域２を設ける。
【００６９】
図４(ｄ)において回収部５を囲む前記β≧７０％の分散状態で被覆を始める被覆空間の被覆開始領域２を設ける。
図４(ｅ)において高分散芯粒子粉体の粒子・気体混合物の粒子のみが到達可能な位置に回収部５を設ける。従って、ここでの領域６は重力を利用した選択手段となる。回収部に入る高分散芯粒子粉体の粒子・気体混合物の粒子が、必ず通過する前記β≧７０％の分散状態で被覆を始める被覆空間の被覆開始領域２を図の斜線部のように設ける。
β≧７０％の分散状態で被覆始めた芯粒子のみ回収でき、被覆開始領域を通っていない芯粒子と被覆開始領域を通過した被覆粒子とは混ざることはない。
【００７０】
上記したところから、被覆された高圧型窒化硼素粒子を製造するための装置は、微粒子高分散処理手段群と被覆室、又は微粒子高分散処理手段群と被覆室と回収手段から構成されるものであるが、これらの装置の構成要素は、種々の組み合わせ方をすることが可能で、これらの装置の構成例を図面にもとづいて説明するとつぎのとおりである。
【００７１】
装置の構成１
図５(ａ)は、被覆された高圧型窒化硼素粒子を製造するための第一の装置の構成を説明するブロック図である。本例のこの装置は、被覆装置の製造装置本体２−Ａ、被覆室２−Ｂ１、被覆空間２−Ｂ２、被覆開始領域２−Ｂ３、微粒子高分散処理手段群２−Ｃ１、回収手段２−Ｄから構成されている。微粒子高分散処理手段群２−Ｃ１は、被覆室２−Ｂ１に直結してある。
【００７２】
装置の構成２
図５(ｂ)は、被覆された高圧型窒化硼素粒子を製造するための第二の装置の構成を説明するブロック図である。本例のこの装置は、被覆装置の製造装置本体２−Ａ、被覆室２−Ｂ１、被覆空間２−Ｂ２、被覆開始領域２−Ｂ３、微粒子高分散処理手段群２−Ｃ１、不可避の中空部材２−Ｃ２、回収手段２−Ｄから構成されている。微粒子高分散処理手段群２−Ｃ１は、被覆室２−Ｂ１に不可避の中空部材２−Ｃ２を介して接続してある。
【００７３】
装置の構成３
図５(ｃ)は、被覆された高圧型窒化硼素粒子を製造するための第三の装置の構成を説明するブロック図である。本例のこの装置は、被覆装置の製造装置本体２−Ａ、被覆室２−Ｂ１、被覆空間２−Ｂ２、被覆開始領域２−Ｂ３、微粒子高分散処理手段群２−Ｃ１、気中分散維持手段２−Ｃ３、回収手段２−Ｄから構成されている。微粒子高分散処理手段群２−Ｃ１は、被覆室２−Ｂ１に気中分散維持手段２−Ｃ３を介して接続してある。
【００７４】
装置の構成４
図５(ｄ)は、被覆された高圧型窒化硼素粒子を製造するための第四の装置の構成を説明するブロック図である。本例のこの装置は、被覆装置の製造装置本体２−Ａ、被覆室２−Ｂ１、被覆空間２−Ｂ２、被覆開始領域２−Ｂ３、微粒子高分散処理手段群２−Ｃ１、回収手段２−Ｄから構成されている。微粒子高分散処理手段群２−Ｃ１は、被覆室２−Ｂ１と空間を共有している。
【００７５】
装置の構成５
図５(ｅ)は、被覆された高圧型窒化硼素粒子を製造するための第五の装置の構成を説明するブロック図である。本例のこの装置は、被覆装置の製造装置本体２−Ａ、被覆室２−Ｂ１、被覆空間２−Ｂ２、被覆開始領域２−Ｂ３、微粒子高分散処理手段群２−Ｃ１、回収手段２−Ｄから構成されている。微粒子高分散処理手段群２−Ｃ１は、被覆室２−Ｂ１中に設けている。
【００７６】
装置の構成６
図５(ｆ)は、被覆された高圧型窒化硼素粒子を製造するための第六の装置の構成を説明するブロック図である。本例のこの装置は、被覆装置の製造装置本体２−Ａ、被覆室２−Ｂ１、被覆空間２−Ｂ２、被覆開始領域２−Ｂ３、微粒子高分散処理手段群２−Ｃ１、回収手段２−Ｄから構成されている。微粒子高分散処理手段群２−Ｃ１の分散空間中に、被覆室２−Ｂ１を設けている。
【００７７】
装置の構成７
図５(ｇ)は、被覆された高圧型窒化硼素粒子を製造するための第七の装置の構成を説明するブロック図である。本例のこの装置は、被覆装置の製造装置本体２−Ａ、被覆室２−Ｂ１、被覆空間２−Ｂ２、被覆開始領域２−Ｂ３、微粒子高分散処理手段群２−Ｃ１、回収手段２−Ｄ、再被覆供給手段２−Ｅから構成されている。回収手段２−Ｄから被覆後の被覆粒子を高分散処理手段群２−Ｃ１に再被覆供給手段２−Ｅにより搬送して、繰り返して被覆処理が行える。
かかる構成の装置のいずれかにより、被覆された高圧型窒化硼素粒子が製造されるものである。
【００７８】
上記のようにして高圧型窒化硼素粒子である芯粒子粉体を被覆形成物質で被覆した被覆粒子について、再び被覆形成物質で被覆すること、またはこの再被覆を反復することもできる。この場合、被覆粒子は再被覆供給手段に送られる。ここで、再被覆供給手段とは、再被覆を行うために被覆後の被覆粒子を微粒子高分散処理手段群へ搬送する手段をいう。具体的には、(ａ)被覆粒子を回収する回収手段、及び(ｂ)回収手段から微粒子高分散処理手段群に被覆粒子を搬送する被覆粒子搬送手段を備えた手段である。または、(ａ)被覆粒子を回収する回収手段、(ｂ)回収手段から微粒子高分散処理手段群に被覆粒子を搬送する被覆粒子搬送手段、(ｃ)及び被覆後の被覆粒子を分級する被覆粒子分級手段を備えた手段である。被覆量が多い場合、被覆前の芯粒子粉体の粒子の粒度分布と被覆後の被覆粒子の粒度分布は変わってしまう。そこで、被覆後の被覆粒子の粒度分布を被覆粒子分級手段により調整し、再被覆処理を行えば効果的である。
この再被覆処理は、必要によって繰り返すことができ、そして被覆形成物質の被覆量を所望のものに設定することができる。更に、この被覆形成物質の種類を変えてこの被覆処理を繰り返すことができ、このようにして複数成分の物質を被覆形成物質として多重被覆することもできる。
【００７９】
本発明で用いる被覆粒子の製造装置は、被覆形成物質が、気相を経る気相法によって、芯粒子粉体の粒子表面に被覆される被覆粒子の製造装置であれば制限はない。例えば、化学蒸着（ＣＶＤ）装置としては、熱ＣＶＤ装置、プラズマＣＶＤ装置、電磁波を利用したＣＶＤ（可視光線ＣＶＤ、レーザＣＶＤ、紫外線ＣＶＤ、赤外線ＣＶＤ、遠赤外線ＣＶＤ）装置、ＭＯＣＶＤ装置等、或いは、物理蒸着（ＰＶＤ）装置としては、真空蒸着装置、イオンスパッタリング装置、イオンプレーティング装置等が適用可能である。より具体的には、例えば、特開平３−７５３０２号公報の超微粒子で表面が被覆された粒子およびその製造方法に記載の被覆粒子製造装置が好適である。
【００８０】
以上述べた通り、本発明では高圧型窒化硼素である微粒子芯粒子粉体、又は主に微粒子からなる芯粒子粉体の粒子を被覆空間に投入し気相を経て生成する被覆形成物質前駆体及び／又は気相状態の被覆形成物質前駆体をこの芯粒子粉体の粒子に接触及び／又は衝突させてこの芯粒子粉体の粒子の表面を被覆形成物質で被覆する被覆高圧型窒化硼素粒子が製造されるが、本発明の基本的な工程を要約すると次の通りである。
【００８１】
Ｉ
（Ａ） 微粒子高分散処理手段群により、体積基準頻度分布で平均粒子径が１０μｍ以下の微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子を、気中に分散させて高分散芯粒子粉体の粒子・気体混合物とする分散工程、
（Ｂ） この分散工程で分散させた高分散芯粒子粉体の粒子・気体混合物の芯粒子粉体の粒子を、分散度βが７０％以上の分散状態で、被覆空間の被覆開始領域において被覆形成物質前駆体と接触及び／又は衝突させて被覆を開始する被覆工程、
を設けた被覆法。
【００８２】
II
（Ａ） 体積基準頻度分布で平均粒子径が１０μｍ以下の微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子を、微粒子高分散処理手段群により分散させた高分散芯粒子粉体の粒子・気体混合物の芯粒子粉体の粒子の分散度βが７０％以上を実現する微粒子高分散処理手段群により気中に分散させて高分散芯粒子粉体の粒子・気体混合物とする分散工程、
（Ｂ） この分散工程で分散させた高分散芯粒子粉体の粒子・気体混合物の芯粒子粉体の粒子を、分散度βが７０％以上の分散状態で、被覆空間の被覆開始領域において被覆形成物質前駆体と接触及び／又は衝突させて被覆を開始する被覆工程、
を設けた被覆法。
【００８３】
III
（Ａ） 体積基準頻度分布で平均粒子径が１０μｍ以下の微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子を、微粒子高分散処理手段群により分散させた高分散芯粒子粉体の粒子・気体混合物の芯粒子粉体の粒子の分散度βが７０％以上を実現する微粒子高分散処理手段群により気中に分散させて高分散芯粒子粉体の粒子・気体混合物とする分散工程、
（Ｂ） この分散工程で分散させた高分散芯粒子粉体の粒子・気体混合物の芯粒子粉体の粒子を、被覆工程に直接搬送する搬送工程、
（Ｃ） この搬送工程で搬送した高分散芯粒子粉体の粒子・気体混合物の芯粒子粉体の粒子を、分散度βが７０％以上の分散状態で、被覆空間の被覆開始領域において被覆形成物質前駆体と接触及び／又は衝突させて被覆を開始する被覆工程、
を設けた被覆法。
【００８４】
IV
（Ａ） 体積基準頻度分布で平均粒子径が１０μｍ以下の微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子を、微粒子高分散処理手段群により分散させた高分散芯粒子粉体の粒子・気体混合物の芯粒子粉体の粒子の分散度βが７０％以上を実現する微粒子高分散処理手段群により気中に分散させて高分散芯粒子粉体の粒子・気体混合物とする分散工程、
（Ｂ） この分散工程で分散させた高分散芯粒子粉体の粒子・気体混合物の芯粒子粉体の粒子を、搬送に不可避の、中空部材、中空を形成する部材からなる中間部材、及びパイプから選択される１種類又はそれ以上の部材を介して搬送する搬送工程、
（Ｃ） この搬送工程で搬送した高分散芯粒子粉体の粒子・気体混合物の芯粒子粉体の粒子を、分散度βが７０％以上の分散状態で、被覆空間の被覆開始領域において被覆形成物質前駆体と接触及び／又は衝突させて被覆を開始する被覆工程、
を設けた被覆法。
【００８５】
Ｖ
（Ａ） 体積基準頻度分布で平均粒子径が１０μｍ以下の微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子を、微粒子高分散処理手段群により分散させた高分散芯粒子粉体の粒子・気体混合物の芯粒子粉体の粒子の分散度βが７０％以上を実現する微粒子高分散処理手段群により気中に分散させて高分散芯粒子粉体の粒子・気体混合物とする分散工程、
（Ｂ） この分散工程で分散させた高分散芯粒子粉体の粒子・気体混合物の芯粒子粉体の粒子を、この分散性能で気中に分散させた高分散芯粒子粉体の粒子・気体混合物の芯粒子粉体の粒子の気中分散状態を維持する気中分散維持手段、この高分散芯粒子粉体の粒子・気体混合物の芯粒子粉体の粒子の気中分散状態を高める気中分散促進手段、芯粒子粉体の粒子と気体との混合物において低分散芯粒子粉体の粒子・気体混合物を分離し、芯粒子粉体の粒子が主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物を選択する高分散芯粒子粉体の粒子・気体混合物選択手段の１種類又はそれ以上を介して搬送する搬送工程、
（Ｃ） この搬送工程で搬送した高分散芯粒子粉体の粒子・気体混合物の芯粒子粉体の粒子を、分散度βが７０％以上の分散状態で、被覆空間の被覆開始領域において被覆形成物質前駆体と接触及び／又は衝突させて被覆を開始する被覆工程、
を設けた被覆法。
【００８６】
以上、Ｉ〜Ｖの全てにおいて、好適には、体積基準頻度分布で平均粒子径が１０μｍ以下の微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子を、微粒子高分散処理手段群により分散させた高分散芯粒子粉体の粒子・気体混合物の芯粒子粉体の粒子の分散度βが７０％以上を実現する空間領域の内の、高分散芯粒子粉体の粒子・気体混合物中の芯粒子粉体の粒子の全ての粒子が通過する面を含む空間領域に、被覆空間の被覆開始領域を位置させるか、又は、
体積基準頻度分布で平均粒子径が１０μｍ以下の微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子を、微粒子高分散処理手段群により分散させた高分散芯粒子粉体の粒子・気体混合物の芯粒子粉体の粒子の分散度βが７０％以上を実現する空間領域の内の、回収手段の回収部に回収する全てに粒子が通過する面を含む空間領域に、被覆空間の被覆開始領域を位置させるか、
又は、前記Ｉ及びIIにおいて、体積基準頻度分布で平均粒子径が１０μｍ以下の微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子を、微粒子高分散処理手段群により分散させた高分散芯粒子粉体の粒子・気体混合物の芯粒子粉体の粒子の分散度βが７０％以上を実現する微粒子高分散処理手段群により気中に分散させて高分散芯粒子粉体の粒子・気体混合物とする分散工程の一部以上と前記被覆工程の一部以上とを、空間を一部以上共有して行うものである。
【００８７】
前記、被覆された高圧型窒化硼素粒子は、被覆された粒子の被覆形成物質を介して、接触状態で集合塊を形成する場合がある。この被覆された高圧型窒化硼素粒子からなる粉体は、単一粒子状態の被覆された粒子と、この単一粒子状態の被覆された粒子が数個から数十個接触した集合塊、更に多数個の単一粒子状態の被覆された粒子が接触した集合塊から構成され、その形状及び大きさが不均一で不規則になる。この単一粒子状態の被覆された粒子からなる集合塊は、解砕及び／又は破砕してから成形又は焼結処理に供するのが好ましい。この被覆された高圧型窒化硼素粒子の集合塊の解砕及び／又は破砕には、種々の解砕手段、例えば、ボールミル、振動ボールミル、乳鉢、ジェットミル等が利用可能である。また、単一粒子状態の被覆された粒子と、この単一粒子状態の被覆された粒子の集合塊とを選択分離して、単一粒子状態の被覆された粒子のみを成形又は焼結処理に供してもよい。
【００８８】
本発明によれば、上記のようにして得られた被覆された高圧型窒化硼素粉体粒子又は同粒子を含む混合物は２０００ ＭＰａ以上の超高圧力・高温下において焼結されて高圧型窒化硼素の焼結体とされる。
この焼結操作に当って、本発明によれば被覆された高圧型窒化硼素粒子のみを用いて焼結することもできるが、これに未被覆の高圧型窒化硼素粉体を混合して焼結したり、また他の機能を発現する物質を加えて焼結することもできる。
【００８９】
未被覆の高圧型窒化硼素粉体を混合する場合には、被覆された高圧型窒化硼素粒子一個一個の表面は、既に、被覆形成物質が均一に被覆されているので、この被覆された高圧型窒化硼素粒子を、未被覆の高圧型窒化硼素粒子一個一個の周りに接するように適量混合せしめれば、高圧型窒化硼素粒子一個一個に確実に、被覆形成物質を分布させることができるので良好な焼結が可能で、未被覆の高圧型窒化硼素粒子は、前記被覆された高圧型窒化硼素粒子に対し、相対的に粉体粒子径が大きければ、比較的多量に添加してもこの未被覆の高圧型窒化硼素粒子の周りをすべて被覆形成物質でとり巻くように被覆された高圧型窒化硼素粒子を分布させることが可能である。
【００９０】
また靭性強化等の他の機能を発現する物質を加える場合についてはこの物質が粉体状、板状又は粒子状のもので、より具体的には、周期律表第１ａ、２ａ、３ａ、４ａ、５ａ、６ａ、７ａ、１ｂ、２ｂ、３ｂ、４ｂ、８族の金属、半導体、半金属、希土類金属、及びその酸化物、窒化物、炭化物、酸窒化物、酸炭化物、炭窒化物、酸炭窒化物、硼化物、珪化物の内の選択された一種類以上のもの、例えばＡｌ、Ｂ、Ｓｉ、Ｆｅ、Ｎｉ、Ｃｏ、Ｔｉ、Ｎｂ、Ｖ、Ｚｒ、Ｈｆ、Ｔａ、Ｗ、Ｒｅ、Ｃｒ、Ｃｕ、Ｍｏ、ＴｉＡｌ、Ｔｉ₃Ａｌ、ＴｉＡｌ₃、ＴｉＮｉ、ＮｉＡｌ、Ｎｉ₃Ａｌ、ＳｉＣ、Ｂ₄Ｃ、Ｃｒ₃Ｃ₂、ＴｉＣ、ＺｒＣ、ＷＣ、Ｗ₂Ｃ、ＨｆＣ、ＴａＣ、Ｔａ₂Ｃ、ＮｂＣ、ＶＣ、Ｍｏ₂Ｃ、Ｓｉ₃Ｎ₄、ＴｉＮ、ＺｒＮ、Ｓｉ₂Ｎ₂Ｏ、ｗ−ＢＮ、ｃ−ＢＮ、ＡｌＮ、ＨｆＮ、Ｖ_xＮ（ｘ＝１〜３）、ＮｂＮ、ＴａＮ、Ｔａ₂Ｎ、ＴｉＢ、ＴｉＢ₂、ＺｒＢ₂、ＶＢ、Ｖ₃Ｂ₂、ＶＢ₂、ＮｂＢ、ＮｂＢ₂、ＴａＢ、ＴａＢ₂、ＭｏＢ、ＭｏＢ₂、ＭｏＢ₄、Ｍｏ₂Ｂ、ＷＢ、Ｗ₂Ｂ、Ｗ₂Ｂ₅、ＬａＢ₆、ＢＰ、Ｂ₁₃Ｐ₂、ＭｏＳｉ₂、Ａｌ₂Ｏ₃、ＺｒＯ₂（Ｙ₂Ｏ₃、ＭｇＯ又はＣａＯ安定剤を添加した部分安定化ジルコニア：ＰＳＺ、又は正方晶ジルコニア多結晶体：ＴＺＰ）、ＭｇＡｌ₂Ｏ₄（スピネル）、Ａｌ₂ＳｉＯ₅（ムライト）の少なくとも一種類からなる粉体及び／又は粒子等から選択されうる。
【００９１】
更にこの物質が繊維状物質であっても良い。この被覆高圧型窒化硼素粉体粒子に混合せしめる、繊維状物質は短径が５００μｍ以下で、短径に対する長径との比が２以上である形状の、金属又は化合物の少なくとも一種類からなる物質で、短径が５００μｍ以下で、短径に対する長径との比が２以上である形状の棒状物質及び／又は融解紡糸して繊維形状にした連続繊維である長繊維及び／又は結晶自体が繊維形状をとる自形繊維である短繊維及び／又は一方向に結晶成長させて繊維形状にしたウィスカー（wisker）からなる。このウィスカー（ヒゲ結晶）には、その形成においては、相変化や体積全体に及ぼす化学反応という現象は起こらないものと定義されている真性のウィスカー及び／又は相変化とか体積全体に及ぶ化学変化によって生成する結晶の一つの結晶面のみを成長させることにより、長い針状晶となった単結晶を指す広義のウィスカー及び／又は断面積が８×１０^-5 in²以下で、長さが平均直径の１０倍以上の単結晶であるウィスカーがある。
【００９２】
繊維状物質として、周期律表第１ａ、２ａ、３ａ、４ａ、５ａ、６ａ、７ａ、１ｂ、２ｂ、３ｂ、４ｂ、５ｂ、６ｂ、７ｂ、８族の金属、半導体、半金属、希土類金属、非金属の内の一種類以上を含む化合物の少なくとも一種類を含む。短径が５００μｍ以下で、短径に対する長径との比が２以上である形状の繊維状物質が用いられる。具体的には、周期律表第１ａ、２ａ、３ａ、４ａ、５ａ、６ａ、７ａ、１ｂ、２ｂ、３ｂ、４ｂ、８族の金属、半導体、半金属、希土類金属、及びその炭化物、酸化物、窒化物、酸炭化物、酸窒化物、炭窒化物、酸炭窒化物、硼化物、珪化物の少なくとも一種類からなる、短径が５００μｍ以下で、短径に対する長径との比が２以上である形状の繊維状物質が使用される。好適には、例えば、Ａｌ、Ｂ、Ｓｉ、Ｆｅ、Ｎｉ、Ｃｏ、Ｔｉ、Ｎｂ、Ｖ、Ｚｒ、Ｈｆ、Ｔａ、Ｗ、Ｒｅ、Ｃｒ、Ｃｕ、Ｍｏ、ＴｉＡｌ、Ｔｉ₃Ａｌ、ＴｉＡｌ₃、ＴｉＮｉ、ＮｉＡｌ、Ｎｉ₃Ａｌ、ＳｉＣ、Ｂ₄Ｃ、Ｃｒ₃Ｃ₂、ＴｉＣ、ＺｒＣ、ＷＣ、Ｗ₂Ｃ、ＨｆＣ、ＴａＣ、Ｔａ₂Ｃ、ＮｂＣ、ＶＣ、Ｍｏ₂Ｃ、Ｓｉ₃Ｎ₄、ＴｉＮ、ＺｒＮ、Ｓｉ₂Ｎ₂Ｏ、ＡｌＮ、ＨｆＮ、Ｖ_xＮ（ｘ＝１〜３）、ＮｂＮ、ＴａＮ、Ｔａ₂Ｎ、ＴｉＢ、ＴｉＢ₂、ＺｒＢ₂、ＶＢ、Ｖ₃Ｂ₂、ＶＢ₂、ＮｂＢ、ＮｂＢ₂、ＴａＢ、ＴａＢ₂、ＭｏＢ、ＭｏＢ₂、ＭｏＢ₄、Ｍｏ₂Ｂ、ＷＢ、Ｗ₂Ｂ、Ｗ₂Ｂ₅、ＬａＢ₆、ＢＰ、Ｂ₁₃Ｐ₂、ＭｏＳｉ₂、Ａｌ₂Ｏ₃、ＺｒＯ₂（Ｙ₂Ｏ₃、ＭｇＯ又はＣａＯ安定剤を添加した部分安定化ジルコニア：ＰＳＺ、又は正方晶ジルコニア多結晶体：ＴＺＰ）、ＭｇＡｌ₂Ｏ₄（スピネル）、Ａｌ₂ＳｉＯ₅（ムライト）の少なくとも一種類からなる、短径が５００μｍ以下で、短径に対する長径との比が２以上でなる形状の繊維状物質が選択されうる。
【００９３】
本発明で用いる被覆高圧型窒化硼素粒子は、上記したように気相法によりその表面を被覆するので基本的に被覆形成物質に制限はない。被覆高圧型窒化硼素焼結体を、用途に応じて任意に材料設計する上で必要に応じて、被覆を施す前に、高圧型窒化硼素粉体粒子表面に事前に、同種及び／又は異種の被覆形成物質を同種及び／又は異種の被覆方法により被覆を施してもよい。
【００９４】
例えば、高圧型窒化硼素粒子表面に、目的とする金属の炭化物からなる被覆を形成する場合、事前に炭素を被覆した被覆高圧型窒化硼素粒子を使用すればよい。事前に物質を被覆する方法は、特に制限するものではないが、例えば、特開平２−２５２６６０号公報に記載の溶融塩浸漬法を始め、電気メッキ法、無電解メッキ法、クラッド法、物理蒸着法（スパッタリング法、イオンプレーティング法等）や化学蒸着法等が好適である。目的とする金属化合物の金属の種類は、本発明の結合材及び／又は焼結助剤として適用可能の範囲であれば特に制限されない。
【００９５】
本発明によれば高圧型窒化硼素粒子表面に、気相法により、被覆形成物質を被覆させた被覆高圧型窒化硼素粒子を単独で、又は被覆高圧型窒化硼素粒子と、残部が前記粉体、板状物質、粒子等及び／又は前記繊維状物質を混合した混合物を、粉体状で、若しくは成形後、２０００ ＭＰａ以上の超高圧力・高温下で適宜時間焼結する。圧力は２０００ ＭＰａ以上であればいかなる圧力であっても良く、また温度は高圧型窒化硼素が事実上安定に存在し且つ焼結しようとする被覆高圧型窒化硼素粒子が焼結可能であるいかなる範囲の温度であってもよい。
静的な２０００ ＭＰａ以上の超高圧力・高温を発生する超高圧力装置は、キュービック型、テトラ型、ガードル型、ベルト型等が適用可能で、特に制限はない。
動的な２０００ ＭＰａ以上の超高圧力・高温を発生する装置・方法は、例えば爆薬レンズ（平面爆薬発生装置）や円筒状爆発発生装置、飛翔体衝突方法、磁場爆縮方法、マッハ爆発方法、過大爆発方法、円錐状爆縮方法等や一般式衝撃銃、二段式軽ガス銃等の公知の装置・方法が適用可能で特に制限はない。これらの動的な超高圧力・高温を発生する装置・方法によれば、発生できる圧力は１０ ＧＰａ（１０,０００ ＭＰａ）以上、好適には４０ ＧＰａ以上であるので、特に高い圧力を短時間作用させる場合の好適な例として選択できる。
【００９６】
目的により、例えば再現性良く試料を加圧するための加圧装置及び圧力は、前記キュービック型超高圧力装置を始めとする各種静的に超高圧力を発生する超高圧力装置を使用し、２０００MPa以上とする。焼結温度は、前記立方晶窒化硼素の熱力学的安定領域から若干外れた条件でも差し支えない。
しかし、より好適には、２０００ＭＰａ以上の超高圧力・高温下の高圧型窒化硼素の熱力学的安定領域の条件で焼結せしめる。
【００９７】
一例として、立方晶窒化硼素粉体を原料として用いた、キュービック型超高圧力装置による、高圧型窒化硼素焼結体の製造について説明すると、先ず、立方晶窒化硼素粉体粒子表面に被覆形成物質を被覆した被覆された高圧型窒化硼素粉体粒子を、ペレット状に型押し成形し、その外側に六方晶窒化硼素（ｈ−ＢＮ）成形体で囲って、更にその外側に黒鉛管ヒータを配置する。このヒータの外側には、７００℃で加熱処理することにより結晶水を除去したパイロフィライトを固体圧力媒体として配置する。このようにして構成した試料を、キュービック型超高圧力装置に配置し、所定の圧力まで昇圧し、その後、所定の温度まで昇温して、適宜時間焼結する。焼結後、降温し、そして降圧する。キュービック型超高圧力装置から圧力媒体を取り出し、この圧力媒体から試料を取り出す。このようにして、結合材及び／又は焼結助剤及び／又は表面改質剤の分布が制御された、均一で緻密で、高度に制御された微組織を有する特徴的な、高圧型窒化硼素から構成された高性能な被覆高圧型窒化硼素焼結体を得る。
【００９８】
【実施例】
以下、本発明の被覆高圧型窒化硼素焼結体及びその製造法を実施例によって更に詳細に説明する。
実施例１
高圧型窒化硼素粉体粒子として、平均粒子径Ｄ_Ｍが１μｍで、体積基準頻度分布が（〔Ｄ_Ｍ／２，３Ｄ_Ｍ／２〕，≧９０％）の立方晶窒化硼素粒子をジルコニウム金属で被覆した。
使用した装置は、図６及びその部分拡大図である図７に示したものであり、図５（ａ）に示した構成の具体例である。
本例の装置は、プラズマトーチ３−Ａ、プラズマ室３−ａ、被覆形成物質前駆体生成室の冷却槽３−Ｂ、被覆形成物質前駆体生成室３−ｂ、狭義の被覆室冷却槽３−Ｃ、狭義の被覆室３−ｃ、被覆粒子冷却室の冷却槽３−Ｄ、被覆粒子冷却室３−ｄ、被覆形成物質の原料の供給側に、供給装置３−Ｅ１、芯粒子粉体の供給側に、撹拌式分散機３−Ｆ１とエジェクター式分散機３−Ｈ１、細管分散機１０７及び被覆粒子回収部３−Ｇより成る。供給装置３−Ｅ１は被覆形成物質の原料粉体の供給槽を備えた供給機１１２に、撹拌式分散機３−Ｆ１は芯粒子粉体の供給槽を備えた供給機１１１にそれぞれ結合される。本例における被覆室は、定義ではプラズマ室３−ａ、被覆形成物質前駆体生成室３−ｂ、狭義の被覆室３−ｃ、被覆粒子冷却室３−ｄから構成されており、ここではこれらを広義の被覆室と称する。広義の被覆室の内、主に被覆処理の行われる室３−ｃを狭義の被覆室と称する。
【００９９】
本例における微粒子高分散処理手段群αは、供給槽を備えた供給機１１１、撹拌式分散機３−Ｆ１とエジェクター式分散機３−Ｈ１及び内径４mmのステンレス製細管分散機１０７で構成されており、図２(ａ)に示したものであり、図３(ｂ)に示した構成に属する微粒子高分散処理手段群の具体例である。微粒子高分散処理手段群は、Ｄ_M＝１μｍの（〔Ｄ_M／５，５Ｄ_M〕，≧９０％）の高圧型窒化硼素の芯粒子粉体の粒子に対して出力時β≧７０％を実現できるように構成されている。微粒子高分散処理手段群の最終処理手段である細管１０７は被覆室３−Ｃに直結してあり、被覆空間の３−Ｌ２の被覆開始領域３−Ｌ１においてβ≧７０％を実現できるように構成されている。
【０１００】
プラズマトーチ３−Ａの上部に設けられたガス噴出口１０１に供給源１０２からアルゴンガスを２０リットル／分の割合で供給する。このアルゴンガスは印加された高周波によってプラズマ化され、プラズマトーチ３−Ａ内プラズマ室３−ａでプラズマ焔を形成する。
被覆形成物質の原料の供給槽を備えた供給機１１２から供給した被覆形成物質の原料である平均粒子径１２μｍのジルコニウム金属の粉末は、５リットル／分のキャリアガス１０３に担持されて、プラズマトーチ３−Ａの下部に設けられた被覆形成物質の原料の投入口１０４から、プラズマ焔中に０.６ｇ／分の割合で導入され、プラズマ焔の熱により蒸発して気相を経て、被覆形成物質前駆体生成室３−ｂで被覆形成物質前駆体となる。
芯粒子粉体の供給槽を備えた供給機１１１から１.２ｇ／分で供給される平均粒子径１μｍの立方晶窒化硼素の芯粒子を、撹拌式分散機３−Ｆ１により分散させ、５リットル／分の割合で供給されるキャリアガス１０５により担持され、１０リットル／分の流量の分散ガス１０６によるエジェクター式分散機３−Ｈ１及び細管分散機１０７により分散度β＝８２％の分散状態に分散させ、被覆室に導入する。
高分散状態の立方晶窒化硼素粒子は、被覆空間の３−Ｌ２の被覆開始領域３−Ｌ１において被覆形成物質前駆体とβ＝８２％の分散状態で接触及び／又は衝突し始める。
【０１０１】
このようにして生成した、被覆形成物質で表面に被覆が施された被覆された立方晶窒化硼素粒子は、気体と共に被覆粒子冷却室３−ｄを降下し、被覆粒子回収部３−Ｇに至る。当該被覆粒子からなる製品は、フィルター１１０により気体と分離し、集められ取り出される。
このようにして立方晶窒化硼素粒子にジルコニウム金属が体積で２０％被覆が施された、被覆された立方晶窒化硼素粒子が得られた。
【０１０２】
得られた被覆された立方晶窒化硼素粒子である、ジルコニウム金属で表面に被覆を施した立方晶窒化硼素微粒子を走査型電子顕微鏡で観察したところ、図８に示す通り、個々の粒子は、いずれも、一様に０.００５μｍ程度のジルコニウム金属が超微粒子状に被覆したものであった。
このジルコニウム金属を体積で２０％被覆を施した被覆された立方晶窒化硼素粒子粉体を外径６mm、高さ２mmに型押し成形し、その外側に六方晶窒化硼素（ｈ−ＢＮ）成形体を配置した圧力媒体に埋め込み、２００℃、１０^-3 torrで一昼夜真空乾燥して、低沸点不純物を除去した。これをキュービック型超高圧装置にセットし、先ず室温で５.５GPaまで昇圧し、その後１４５０℃に昇温し、３０分保持後に降温し、圧力を下げた。
【０１０３】
得られた焼結体をＸ線回折で調べたところ、ジルコニウムと立方晶窒化硼素が反応してジルコニウム金属は消失し、立方晶窒化硼素とＺｒＮとＺｒＢ₂に変化した。この焼結体はＸ線定量分析によれば、立方晶窒化硼素、ＺｒＮ及びＺｒＢ₂の体積割合は、それぞれ約７７％、１４％及び９％であった。
得られた焼結体の表面をダイヤモンドペーストで研磨し、ビッカース微小硬度（Ｈｖ）を測定した。図９は実施例１の立方晶窒化硼素焼結体のＨｖ（０.５／１０）であり、比較のため、セラミック系の結合材又は焼結助剤を用いた立方晶窒化硼素焼結体からの、代表的な市販の４種類の切削工具の硬度も示した。実施例１で得られた焼結体のＨｖ（０.５／１０）は、約５５００と大変高硬度であった。この値は、市販の立方晶窒化硼素焼結体切削工具と同等以上であった。しかも、実施例１の焼結体の硬度は、焼結体の硬度測定面全般に渡って一定であり、ばらつきは殆どなかった。
【０１０４】
実施例１の焼結体の研磨面に、観察のための通常の金蒸着を施した研摩面の電子顕微鏡写真（×５０００）を図１０に示す。図中、暗部は立方晶窒化硼素であり、明部はＺｒＮ−ＺｒＢ₂系物質である。図１０から明らかなように、焼結体中には気孔が全く存在せず、相対密度１００％に焼結出来た。しかも、未焼結部分が全然なかった。被覆形成物質が薄くなって立方晶窒化硼素粒子同志が接触しているところは、当該立方晶窒化硼素粒子同志が被覆を押し破り、焼結して直接結合している。これ以外では、ＺｒＮ−ＺｒＢ₂系物質が立方晶窒化硼素粒子を取り巻いて分布し、緻密で、均一な、微組織が高度に制御された結合材分布を有する特徴的な焼結体であることが分かる。しかも、立方晶窒化硼素粒子は、原料の立方晶窒化硼素粉体と比べ、粒成長がなく、且つ立方晶窒化硼素と被覆形成物質であるジルコニウム金属が化学反応して被覆を形成するため、焼結体中の立方晶窒化硼素粒子は、むしろ被覆前の原料時に比べ、細かくなっているという特徴もある。このことは、焼結体の機械的特性に極めて好都合となっており、理想的である。これらの特徴を、図１１に示した前記市販の代表的な立方晶窒化硼素焼結体切削工具の研磨面に、観察のための通常の金蒸着を施した研摩面の電子顕微鏡写真（×５０００）と比べると、その違いが明確に分かる。即ち、市販の立方晶窒化硼素焼結体切削工具においては、結合材や焼結助剤の分布が不規則的で、その結合材や焼結助剤が塊状になっているところがあり、またその反面、焼結助剤や結合材の欠乏しているところも少なからず存在し、そこに未焼結な部分が見受けられる。更に、この切削工具の立方晶窒化硼素粒子がいずれも粗いこと等が実施例１と大きく異なる点として挙げられる。
以上のように、立方晶窒化硼素は、本来極めて難焼結性であるにもかかわらず、本発明の被覆立方晶窒化硼素粉体粒子は、工業レベルの超高圧力・高温下において、恰も比較的焼結し易い粒子のごとく振る舞い、緻密で強固、且つ高硬度な組織を形成した。
【０１０５】
実施例２
平均粒子径Ｄ_Ｍが１μｍで、体積基準頻度分布が（〔Ｄ_Ｍ／２，３Ｄ_Ｍ／２〕，≧９０％）の立方晶窒化硼素粒子をチタン金属で被覆した。
使用した装置は、図１２及びその部分拡大図である図１３に示したものであり、図５（ｄ）に示した構成の具体例である。本例の被覆形成物質前駆体を生成する装置の構成は実施例１と同一である。微粒子高分散処理手段群αは、供給槽を備えた供給機２１４、撹拌式分散機５−Ｆ１、細管分散機２１１及び衝突板を利用した分散機５−Ｈ２で構成されており、図２（ａ）に示したものであり、図３（ｂ）に示した構成に属する微粒子高分散処理手段群の具体例である。細管分散機２１１は、内径４ｍｍのステンレス製である。微粒子高分散処理手段群αの最終分散手段である衝突板を利用した分散機５−Ｈ２は、ＳｉＣ製の衝突板２１３がステンレス製のホルダー２１２により設置された構成である。衝突板を利用した分散機５−Ｈ２は狭義の被覆室５−ｃの中に設けられており、微粒子高分散処理手段群αと狭義の被覆室５−ｃは共有の空間を有している。また、被覆空間５−Ｌ１及び被覆空間の被覆開始領域５−Ｌ２は、狭義の被覆室５−ｃ内に設けてある。本装置の微粒子高分散処理手段群は、平均粒子径Ｄ_Ｍが１μｍで、体積基準頻度分布が（〔Ｄ_Ｍ／５，５Ｄ_Ｍ〕，≧９０％）の芯粒子粉体の粒子を、最終の分散処理である衝突板を利用した分散機５−Ｈ２の衝突板２１３を衝突直後、分散度β≧７０％に分散できる。したがって、分散度β≧７０％の状態で被覆が開始される
【０１０６】
プラズマトーチ５−Ａの上部に設けられたガス噴出口２０１に供給源２０２から２０リットル／分のアルゴンガスを供給する。このアルゴンガスは印加された高周波によってプラズマ化され、プラズマトーチ５−Ａ内プラズマ室５−ａでプラズマ焔を形成する。
被覆形成物質の原料の供給槽を備えた供給機２１５から０.４ｇ／分で供給した被覆形成物質の原料である平均粒子径２５μｍのチタン金属の粉末は、５リットル／分のキャリアガス２０３に担持されて、プラズマトーチ５−Ａの下部に設けられた被覆形成物質の原料の投入口２０４から、プラズマ焔中に導入され、プラズマ焔の熱により蒸発して気相を経て、被覆形成物質前駆体生成室５−ｂで被覆形成物質前駆体となる。
芯粒子粉体の供給槽を備えた供給機２１４から１.２ｇ／分で供給される立方晶窒化硼素の芯粒子は、撹拌式分散機５−Ｆ１により分散せしめ、２０リットル／分の割合で供給されるキャリアガス２０５により担持され、細管分散機２１１を経て、被覆室中に設けた衝突板を利用した分散機５−Ｈ２によって、分散度β＝８２％に気中に分散させる。
高分散状態の立方晶窒化硼素の芯粒子は、被覆空間５−Ｌ２の被覆開始領域５−Ｌ１において被覆形成物質前駆体とβ＝８２％の分散状態で接触及び／又は衝突し始める。
【０１０７】
このようにして生成した、被覆形成物質で表面に被覆が施された被覆された立方晶窒化硼素粒子は、気体と共に被覆粒子冷却室５−ｄを降下し、被覆粒子回収部５−Ｇに至る。被覆された立方晶窒化硼素粒子からなる製品は、フィルター２１０により気体と分離し、集められ取り出される。
得られた被覆された立方晶窒化硼素粒子である、チタン金属で表面に被覆を施した立方晶窒化硼素微粒子を、走査型電子顕微鏡で観察したところ、個々の粒子は、いずれも、一様に０.００５μｍ程度のチタン金属が超微粒子状に被覆したものであった。チタン金属の被覆量は、体積で２０％であった。
【０１０８】
このようにして得たチタン金属を体積で２０％被覆を施した被覆された立方晶窒化硼素粒子粉体を外径６ｍｍ、高さ２ｍｍに型押し成形し、実施例１と同様に、キュービック型超高圧装置にセットし、先ず、室温で５．３ＧＰａまで昇圧し、その後１４８０℃に昇温し、３０分保持後に降温し、圧力を下げた。得られた焼結体は気孔が全く存在せず、相対密度１００％に緻密化でき、しかも未焼結部分が全然なかった。この焼結体の表面をダイヤモンドペーストで研摩し、ビッカース微小硬度を測定したところＨｖ（０．５／１０）が約５６００と高硬度であった。この焼結体の結晶相を粉末Ｘ線回折により調べたところ、立方晶窒化硼素、ＴｉＮ及びＴｉＢ_２が認められたのみであった。焼結体は、Ｘ線定量分析によれば、立方晶窒化硼素、ＴｉＮ及びＴｉＢ_２の体積割合は、それぞれ約７４％、１５％及び１１％であった。
また、実施例１と同様にこの実施例２においても焼結体は、緻密で、均一で且つほぼ結合材の均一な分布の、高度に制御された微組織が成立した。
【０１０９】
実施例３
平均粒子径が１μｍで、体積基準頻度分布が（〔Ｄ_M／２，３Ｄ_M／２〕，≧９０％）の立方晶窒化硼素粒子をチタン金属の窒化物である窒化チタンで被覆した。
使用した装置は、図１４及びその部分拡大図である図１５に示したものであり、図５(ｂ)に示した構成の具体例である。本例の被覆形成物質前駆体を生成する装置の構成は実施例１と同一である。微粒子高分散処理手段群αは、供給槽を備えた供給機３１３、分散手段である撹拌式分散機６−Ｆ１、高分散芯粒子粉体の粒子・気体混合物選択手段であるサイクロン６−Ｉで構成されており、図２(ｂ)に示したものであり、図３(ｄ)に示した構成の微粒子高分散処理手段群の具体例である。サイクロン６−Ｉの高分散芯粒子粉体の粒子・気体混合物の放出部は、搬送に不可避のパイプ３０７で狭義の被覆室６−ｃへ接続してあり、低分散芯粒子粉体部分の放出部は、ホッパー６−Ｊ、ロータリーバルブ６−Ｋを介して搬送管３１０で撹拌式分散機６−Ｆ１へ接続してある。本装置の微粒子高分散処理手段群によれば、体積基準の粒度分布として、平均粒子径Ｄ_Mが１μｍで、体積基準頻度分布が（〔Ｄ_M／５，５Ｄ_M〕，≧９０％）の芯粒子粉体の粒子を、最終の処理手段であるサイクロン６−Ｉの高分散芯粒子粉体流の放出部で、分散度β≧７５％に分散できる。狭義の被覆室６−ｃに図１４及び図１５のごとく被覆空間６−Ｌ２及び被覆空間の被覆開始領域６−Ｌ１が設けてある。６−Ｃと６−Ｄを結合するフランジ部の制約による搬送に不可避のパイプ３０７による分散度βの低下は少なくとどめられる。したがって、被覆開始領域において、分散度β≧７０％で被覆が開始される。
【０１１０】
プラズマトーチ６−Ａの上部に設けられたガス噴出口３０１に供給源３０２からアルゴンガスを２０リットル／分で供給する。このアルゴンガスは印加された高周波によってプラズマ化され、プラズマトーチ６−Ａ内プラズマ室６−ａでプラズマ焔を形成する。
被覆形成物質の原料の供給槽を備えた供給機３１４から０.６ｇ／分で供給した被覆形成物質の原料である窒化チタン粉末は、５リットル／分のキャリアガス３０３に担持されて、プラズマトーチ６−Ａの下部に設けられた被覆形成物質の原料の投入口３０４から、プラズマ焔中に導入され、プラズマ焔の熱により蒸発して気相を経て、被覆形成物質前駆体生成室６−ｂで被覆形成物質前駆体となる。
芯粒子粉体の供給槽を備えた供給機３１３から２.０ｇ／分で供給される立方晶窒化硼素の芯粒子は、撹拌式分散機６−Ｆ１により分散させ、１５リットル／分のキャリアガス３０５により担持されパイプ３０６を介してサイクロン６−Ｉに搬送される。サイクロン６−Ｉは、微粉側の最大粒子径が１.５μｍとなるように調節されており、主に単一粒子からなるβ＝８５％の分散状態の高分散芯粒子粉体の粒子・気体混合物を、搬送に不可避のパイプ３０７を介し放出口３０８から狭義の被覆室６−ｃに放出させる。一方、サイクロン６−Ｉにより選択分離した低分散芯粒子粉体部分は、ホッパー６−Ｊ、ロータリーバルブ６−Ｋを経て、１０リットル／分のキャリアガス３０９によりパイプ３１０中を搬送され、撹拌式分散機６−Ｆ１へフィードバックする。
【０１１１】
高分散状態の立方晶窒化硼素の芯粒子は、被覆空間６−Ｌ２の被覆開始領域６−Ｌ１において被覆形成物質前駆体とβ＝８２％の分散状態で接触及び／又は衝突し始める。
このようにして生成した、被覆形成物質で表面に被覆が施された被覆された立方晶窒化硼素粒子は、気体と共に被覆粒子冷却室６−ｄを降下し、被覆粒子回収部６−Ｇに至る。被覆された立方晶窒化硼素粒子からなる製品は、フィルター３１２により気体と分離し、集められ取り出される。
【０１１２】
得られた被覆粒子である、窒化チタンで表面を被覆した立方晶窒化硼素微粒子を、走査型電子顕微鏡で観察したところ、個々の粒子は、いずれも、一様に０.００５μｍ程度の窒化チタンが超微粒子状に被覆したものであった。窒化チタンの被覆量は、体積で１５％であった。
このように得た窒化チタンを体積で１５％被覆を施した被覆された立方晶窒化硼素粉体を外径６mm、高さ２mmに型押し成形し、実施例１と同様に、キュービック型超高圧装置にセットし、先ず、室温で５.３GPaまで昇圧し、その後１４８０℃に昇温し、３０分保持後に降温し、圧力を下げた。得られた焼結体は気孔が全く存在せず、相対密度１００％に緻密化でき、しかも未焼結部分が全然なかった。この焼結体の表面をダイヤモンドペーストで研摩し、ビッカース微小硬度を測定したところＨｖ（０.５／１０）が約６４００と高硬度であった。この焼結体の結晶相を粉末Ｘ線回折により調べたところ、立方晶窒化硼素、ＴｉＮが認められたのみであった。また、この実施例３においても焼結体は、緻密で、均一で且つほぼ網目状の結合材の分布の、高度に制御された微組織が成立した。
【０１１３】
実施例４
実施例３の装置により、実施例３と略同様の条件で被覆を行って、窒化チタンを体積で２０％被覆を施した被覆された立方晶窒化硼素粒子粉体を得た。この被覆された立方晶窒化硼素粒子粉体を外径６mm、高さ２mmに型押し成形し、実施例３と同様に、キュービック型超高圧装置にセットし、先ず、室温で５.３GPaまで昇圧し、その後１４８０℃に昇温し、３０分保持後に降温し、圧力を下げた。得られた焼結体は気孔が全く存在せず、相対密度１００％に緻密化でき、しかも未焼結部分が全然なかった。この焼結体の表面をダイヤモンドペーストで研摩し、ビッカース微小硬度を測定したところＨｖ（０.５／１０）が約５９００と高硬度であった。この焼結体の結晶相を粉末Ｘ線回折により調べたところ、実施例３と同様、立方晶窒化硼素、ＴｉＮが認められたのみであった。また、この実施例４においても焼結体は、緻密で、均一な結合材の分布の、高度に制御された微組織が成立した。
【０１１４】
実施例５
実施例１の装置により、実施例１と略同様の条件で被覆を行って、窒化アルミニウムを体積で２０％被覆を施した被覆された立方晶窒化硼素粒子粉体を得た。この被覆された立方晶窒化硼素粒子粉体を外径６mm、高さ２mmに型押し成形し、実施例１と同様に、キュービック型超高圧装置にセットし、先ず、室温で５.４GPaまで昇圧し、その後１４５０℃に昇温し、３０分保持後に降温し、圧力を下げた。得られた焼結体は気孔が全く存在せず、相対密度１００％に緻密化でき、しかも未焼結部分が全然なかった。この焼結体の表面をダイヤモンドペーストで研摩し、ビッカース微小硬度を測定したところＨｖ（０.５／１０）が約５８００と高硬度であった。この焼結体の結晶相を粉末Ｘ線回折により調べたところ、立方晶窒化硼素及びＡｌＮが認められたのみであった。また、この実施例５においても焼結体は、緻密で、均一な結合材の分布の、高度に制御された微組織が成立した。
【０１１５】
実施例６
実施例１の装置により、実施例５と略同様の条件で被覆を行って、窒化アルミニウムを体積で３０％被覆を施した被覆された立方晶窒化硼素粒子粉体を得た。この被覆された立方晶窒化硼素粒子粉体を外径６mm、高さ２mmに型押し成形し、実施例５と同様に、キュービック型超高圧装置にセットし、先ず、室温で５.４GPaまで昇圧し、その後１４５０℃に昇温し、３０分保持後に降温し、圧力を下げた。得られた焼結体は気孔が全く存在せず、相対密度１００％に緻密化でき、しかも未焼結部分が全然なかった。この焼結体の表面をダイヤモンドペーストで研摩し、ビッカース微小硬度を測定したところＨｖ（０.５／１０）が約５２００と高硬度であった。この焼結体の結晶相を粉末Ｘ線回折により調べたところ、実施例５と同様、立方晶窒化硼素及びＡｌＮが認められたのみであった。また、この実施例６においても焼結体は、緻密で、均一な結合材の分布の、高度に制御された微組織が成立した。
【０１１６】
実施例７
実施例１の装置により、実施例１と略同様の条件で被覆を行って、窒化ケイ素を体積で２０％被覆を施した被覆された立方晶窒化硼素粒子粉体を得た。この被覆された立方晶窒化硼素粒子粉体を外径６mm、高さ２mmに型押し成形し、実施例１と同様に、キュービック型超高圧装置にセットし、先ず、室温で５.３GPaまで昇圧し、その後１４７０℃に昇温し、３０分保持後に降温し、圧力を下げた。得られた焼結体は気孔が全く存在せず、相対密度１００％に緻密化でき、しかも未焼結部分が全然なかった。この焼結体の表面をダイヤモンドペーストで研摩し、ビッカース微小硬度を測定したところＨｖ（０.５／１０）が約５９００と高硬度であった。この焼結体の結晶相を粉末Ｘ線回折により調べたところ、立方晶窒化硼素、α−Ｓｉ₃Ｎ₄、β−Ｓｉ₃Ｎ₄が認められたのみであった。また、この実施例７においても焼結体は、緻密で、均一な結合材の分布の、高度に制御された微組織が成立した。
【０１１７】
実施例８
実施例１の装置により、実施例７と略同様の条件で被覆を行って、窒化ケイ素を体積で３０％被覆を施した被覆された立方晶窒化硼素粒子粉体を得た。この被覆された立方晶窒化硼素粒子粉体を外径６mm、高さ２mmに型押し成形し、実施例７と同様に、キュービック型超高圧装置にセットし、先ず、室温で５.３GPaまで昇圧し、その後１４７０℃に昇温し、３０分保持後に降温し、圧力を下げた。得られた焼結体は気孔が全く存在せず、相対密度１００％に緻密化でき、しかも未焼結部分が全然なかった。この焼結体の表面をダイヤモンドペーストで研摩し、ビッカース微小硬度を測定したところＨｖ（０.５／１０）が約５１００と高硬度であった。この焼結体の結晶相を粉末Ｘ線回折により調べたところ、実施例７と同様、立方晶窒化硼素、α−Ｓｉ₃Ｎ₄、β−Ｓｉ₃Ｎ₄が認められたのみであった。また、この実施例８においても焼結体は、緻密で、均一な結合材の分布の、高度に制御された微組織が成立した。
【０１１８】
実施例９
実施例２の装置により、実施例２と略同様の条件で被覆を行って、酸化アルミニウムを体積で１５％被覆を施した被覆された立方晶窒化硼素粒子粉体を得た。この被覆された立方晶窒化硼素粒子粉体を外径６mm、高さ２mmに型押し成形し、実施例２と同様に、キュービック型超高圧装置にセットし、先ず、室温で５.５GPaまで昇圧し、その後１４５０℃に昇温し、３０分保持後に降温し、圧力を下げた。得られた焼結体は気孔が全く存在せず、相対密度１００％に緻密化でき、しかも未焼結部分が全然なかった。この焼結体の表面をダイヤモンドペーストで研摩し、ビッカース微小硬度を測定したところＨｖ（０.５／１０）が約６１００と高硬度であった。この焼結体の結晶相を粉末Ｘ線回折により調べたところ、立方晶窒化硼素、α−Ａｌ₂Ｏ₃が認められたのみであった。また、この実施例９においても焼結体は、緻密で、均一な結合材の分布の、高度に制御された微組織が成立した。
【０１１９】
実施例１０
実施例２の装置により、実施例９と略同様の条件で被覆を行って、酸化アルミニウムを体積で２０％被覆を施した被覆された立方晶窒化硼素粒子粉体を得た。この被覆された立方晶窒化硼素粒子粉体を外径６mm、高さ２mmに型押し成形し、実施例９と同様に、キュービック型超高圧装置にセットし、先ず、室温で５.６GPaまで昇圧し、その後１４５０℃に昇温し、３０分保持後に降温し、圧力を下げた。得られた焼結体は気孔が全く存在せず、相対密度１００％に緻密化でき、しかも未焼結部分が全然なかった。この焼結体の表面をダイヤモンドペーストで研摩し、ビッカース微小硬度を測定したところＨｖ（０.５／１０）が約５９００と高硬度であった。この焼結体の結晶相を粉末Ｘ線回折により調べたところ、実施例９と同様、立方晶窒化硼素、α−Ａｌ₂Ｏ₃が認められたのみであった。また、この実施例１０においても焼結体は、緻密で、均一な結合材の分布の、高度に制御された微組織が成立した。
【０１２０】
実施例１１
実施例１の装置により、実施例１と略同様の条件で被覆を行って、コバルト金属を体積で１０％被覆を施した被覆された立方晶窒化硼素粒子粉体を得た。この被覆された立方晶窒化硼素粒子粉体を外径６mm、高さ２mmに型押し成形し、実施例１と同様に、キュービック型超高圧装置にセットし、先ず、室温で５.５GPaまで昇圧し、その後１４５０℃に昇温し、３０分保持後に降温し、圧力を下げた。得られた焼結体は、気孔が全く存在せず、相対密度１００％に緻密化でき、しかも未焼結部分が全然なかった。また、この焼結体中にコバルト金属のプールは全くなかった。この焼結体の表面をダイヤモンドペーストで研摩し、ビッカース微小硬度を測定したところＨｖ（０.５／１０）が約６０００と高硬度であった。この焼結体の結晶相を粉末Ｘ線回折により調べたところ、立方晶窒化硼素、コバルトが認められたのみであった。また、この実施例１１においても焼結体は、緻密で、均一な結合材の分布の、高度に制御された微組織が成立した。
【０１２１】
実施例１２
実施例１の装置により実施例１１と略同様の条件で被覆を行って、コバルト金属を体積で３０％被覆を施した被覆された立方晶窒化硼素粒子粉体を得た。この被覆された立方晶窒化硼素粒子粉体を外径６ｍｍ、高さ２ｍｍに型押し成形し、実施例１１と同様に、キュービック型超高圧装置にセットし、先ず、室温で５．５ＧＰａまで昇圧し、その後１４５０℃に昇温し、３０分保持後に降温し、圧力を下げた。得られた焼結体の表面をダイヤモンドペーストで研摩し、ビッカース微小硬度を測定したところＨｖ（０．５／１０）が約２８００と高硬度であった。また密度は１００％であった。この焼結体の結晶相を粉末Ｘ線回折により調べたところ、実施例１１と同様、立方晶窒化硼素、コバルトが認められたのみであった。また、この実施例１２においても焼結体は、緻密で、均一な結合材の分布が成立した。
【０１２２】
実施例１３
実施例１の装置により、実施例１と略同様の条件でＲＦプラズマ法により被覆を行って、先ずニッケル金属を、次いでアルミニウム金属をモル比で３：１でＮｉ_３Ａｌ換算で体積で１５％被覆した被覆立方晶窒化硼素粉体を得た。被覆立方晶窒化硼素粉体を外径６ｍｍ、高さ２ｍｍに型押し成形し、実施例１と同様に、キュービック型超高圧装置にセットし、先ず、室温で５．１ＧＰａまで昇圧し、その後１４５０℃に昇温し、３０分保持後に降温し、圧力を下げた。得られた焼結体は、気孔が全く存在せず、相対密度１００％に緻密化でき、しかも未焼結部分が全然なかった。この焼結体の表面をダイヤモンドペーストで研摩し、ビッカース微小硬度を測定したところＨｖ（０．５／１０）が約４３００と高硬度であった。この焼結体の結晶相を粉末Ｘ線回折により調べたところ、立方晶窒化硼素、Ｎｉ_３Ａｌが認められたのみであった。また、この実施例１３においても焼結体は、緻密で、均一な結合材の分布の、高度に制御された微組織が成立した。
【０１２３】
実施例１４
実施例１の装置により、実施例１３と略同様の条件で被覆を行って、先ずニッケル金属を次いで、アルミニウム金属をモル比で１：１でＮｉＡｌ換算時体積で２０％被覆を施した被覆された立方晶窒化硼素粒子粉体を得た。この被覆された立方晶窒化硼素粒子粉体を外径６mm、高さ２mmに型押し成形し、実施例１３と同様に、キュービック型超高圧装置にセットし、先ず、室温で５.１GPaまで昇圧し、その後１４５０℃に昇温し、３０分保持後に降温し、圧力を下げた。得られた焼結体は気孔が全く存在せず、相対密度１００％に緻密化でき、しかも未焼結部分が全然なかった。この焼結体の表面をダイヤモンドペーストで研摩し、ビッカース微小硬度を測定したところＨｖ（０.５／１０）が約３３００と高硬度であった。この焼結体の結晶相を粉末Ｘ線回折により調べたところ、立方晶窒化硼素、ＮｉＡｌが認められた。また、この実施例１４においても焼結体は、緻密で、均一な結合材の分布の、高度に制御された微組織が成立した。
【０１２４】
実施例１５
実施例４で得た、窒化チタンを体積で２０％被覆を施した被覆された立方晶窒化硼素粒子粉体を体積で９０％、残部が、炭化ケイ素ウィスカー（ＳｉＣ：短径０.５μｍ、平均長さ３０μｍ）を体積で１０％を、アセトン中湿式で混合し、その後真空乾燥して混合物を得た。この混合物を外径６mm、高さ２mmに型押し成形し、実施例４と同様に、キュービック型超高圧装置にセットし、先ず、室温で５.５GPaまで昇圧し、その後１５００℃に昇温し、３０分保持後に降温し、圧力を下げた。得られた焼結体は気孔が全く存在せず、相対密度１００％に緻密化でき、しかも未焼結部分が全然なかった。この焼結体の表面をダイヤモンドペーストで研摩し、ビッカース微小硬度を測定したところＨｖ（０.５／１０）が約５０００と高硬度であった。この焼結体の結晶相を粉末Ｘ線回折により調べたところ、ＳｉＣ以外は、実施例４と同様、立方晶窒化硼素及びＴｉＮが認められたのみであった。この実施例１５においても焼結体は、緻密で、均一で、窒化チタン結合材及びＳｉＣウィスカーが立方晶窒化硼素粒子間に均一に分散した高度に制御された微組織の複合焼結体が得られた。
【０１２５】
実施例１６
実施例１の装置により、実施例７と略同様の条件で被覆を行って、窒化ケイ素を体積で２０％被覆を施した被覆された立方晶窒化硼素粒子粉体を体積で９０％、残部が、炭化ケイ素ウィスカー（ＳｉＣ：短径０.５μｍ、平均長さ３０μｍ）を体積で１０％を、アセトン中湿式で混合し、その後真空乾燥して混合物を得た。この混合物を外径６mm、高さ２mmに型押し成形し、実施例７と同様に、キュービック型超高圧装置にセットし、先ず、室温で５.３GPaまで昇圧し、その後１４７０℃に昇温し、３０分保持後に降温し、圧力を下げた。得られた焼結体は気孔が全く存在せず、相対密度１００％に緻密化でき、しかも未焼結部分が全然なかった。この焼結体の表面をダイヤモンドペーストで研摩し、ビッカース微小硬度を測定したところＨｖ（０.５／１０）が約５１００と高硬度であった。この焼結体の結晶相を粉末Ｘ線回折により調べたところ、ＳｉＣ以外は、実施例７と同様、立方晶窒化硼素、α−Ｓｉ₃Ｎ₄、β−Ｓｉ₃Ｎ₄が認められたのみであった。この実施例１６においても焼結体は、緻密で、均一で、窒化ケイ素結合材及びＳｉＣウィスカーが立方晶窒化硼素粒子間に均一に分散した、高度に制御された微組織の複合焼結体が得られた。
【０１２６】
【発明の効果】
本発明によれば、体積基準頻度分布で平均粒子径が１０μｍ以下の高圧型窒化硼素の微粒子からなる芯粒子粉体を気中に分散させ、この分散した芯粒子粉体の粒子を分散度βが７０％以上である分散状態で被覆形成物質前駆体と接触又は衝突させることによって、単一粒子状態でその表面を被覆形成物質で被覆を施した被覆された高圧型窒化硼素粒子又は同粒子を含む混合物を、２０００ ＭＰａ以上の超高圧力及び高温度で焼結することにより、均一で、緻密で、且つ強固に焼結された、高度に制御された微組織を有する高性能な被覆高圧型窒化硼素焼結体が得られた。
【図面の簡単な説明】
【図１】粉体粒子の分布図であり、(ａ)は分散度βを表わし、(ｂ)は粒径Ｄ₁〜Ｄ₂の範囲の粒子が体積で９０％を占める粉体の粒径対体積基準頻度を表わす。
【図２】 (ａ)〜(ｃ)は微粒子高分散処理手段群の基本構成を示すブロック図。
【図３】 (ａ)〜(ｇ)は微粒子高分散処理手段群の構成をより詳細に説明するブロック図。
【図４】 (ａ)〜(ｅ)は芯粒子粉体に被覆が開始される態様を示す図。
【図５】 (ａ)〜(ｇ)は被覆された高圧型窒化硼素粒子を製造するための装置の構成を説明するブロック図。
【図６】実施例１で用いる装置を示す図。
【図７】実施例１で用いる装置の部分拡大図。
【図８】実施例１で得られた被覆された立方晶窒化硼素粒子の走査型電子顕微鏡写真。
【図９】立方晶窒化硼素焼結体のビッカース微小硬度を示す図。
【図１０】実施例１の焼結体の研摩面の電子顕微鏡写真。
【図１１】市販の立方晶窒化硼素焼結体工具の研摩面の電子顕微鏡写真。
【図１２】実施例２で用いる装置を示す図。
【図１３】実施例２で用いる装置の部分拡大図。
【図１４】実施例３で用いる装置を示す図。
【図１５】実施例３で用いる装置の部分拡大図。[0001]
[Industrial application fields]
The present invention relates to a high-performance high-pressure boron nitride sintered body in which a uniform, dense, and strongly sintered microstructure composed of fine particles is highly controlled, and a method for producing the same.
[0002]
[Prior art]
The high-pressure type boron nitride is composed of cubic boron nitride and / or wurtzite type boron nitride. Cubic boron nitride (c-BN) is based on strong covalent bonding and has many very excellent properties. However, due to its covalent bonding, the self-diffusion coefficient is extremely small, which makes it extremely It is difficult to sinter, and cubic boron nitride is thermodynamically stable only at an ultrahigh pressure, and when the pressure is insufficient at a high temperature, hexagonal boron nitride (h-BN) of a graphite type phase. ) Phase transfer. Wurtzite-type boron nitride (w-BN) is a hardly sinterable material having substantially the same properties as cubic boron nitride, and is thermodynamically stable only under ultra-high pressure and at high temperatures. Then, when the pressure is insufficient, the phase is transferred to the hexagonal boron nitride (h-BN) of the graphite type phase. Note that when wurtzite boron nitride is sintered under ultrahigh pressure and high temperature at which cubic boron nitride is thermodynamically stable, phase transition to cubic boron nitride occurs depending on conditions. In this case, cubic boron nitride is used. Becomes a sintered body containing only or cubic boron nitride. In any case, if no binder or sintering aid is added, strong sintering cannot be achieved unless an extremely high pressure of about 7000 MPa is applied at the same time as a very high temperature of about 2000 K. However, such sintering conditions are extremely harsh and are not suitable for the purpose of producing an industrially high-density high-pressure boron nitride sintered body. Therefore, in order to produce a high-density high-pressure boron nitride sintered body, it is necessary to sinter under industrially applicable conditions, and for that purpose, addition of a binder and / or a sintering aid is indispensable. It is.
In particular, in recent years, high performance of high-density high-pressure boron nitride sintered bodies has been desired. For this purpose, high-pressure boron nitride powder particles are made from high-pressure boron nitride powder particles made of fine particles of 10 μm or less, for example. Therefore, it is required to sinter this into a high-density high-pressure boron nitride sintered body.
[0003]
Conventionally, high-pressure boron nitride sintered bodies have been manufactured mainly by a method of adding a binder and / or a sintering aid in powder form. In this case, even if the binder and / or sintering aid is fine, an ideal uniform addition, that is, a uniform dispersion that evenly spreads over the individual high-pressure boron nitride powder particles is extremely difficult. Even if this uniform dispersion is realized, there is a limit to the meaning of uniformity because the binder and / or sintering aid is added in units of particles. In particular, when the amount of the binder and the sintering aid is small, a portion where the binder and the sintering aid are not present in the sintered body is inevitably formed.
In reality, in many cases, the high-pressure boron nitride powder particles and the binder and / or sintering aid particles are aggregated and exist in a lump in the sintered body, or are unevenly distributed in the sintered body. To do. For this reason, particularly in the portion where the high-pressure boron nitride particles are aggregated and present, it is the same as the addition of no binder or sintering aid, and remains unsintered locally. Further, in the portion where the binder and / or the sintering aid are aggregated and present, a portion where the high-pressure boron nitride particles are not present in the sintered body can be formed microscopically. This is a defect that significantly reduces the performance of the sintered body.
Therefore, in order to produce a high-performance high-pressure boron nitride sintered body free from the above defects, it is necessary to reliably distribute the binder and / or sintering aid to each high-pressure boron nitride powder particle. Therefore, high-performance boron nitride powder particles are coated with high-pressure boron nitride powder particles uniformly coated with a coating material and / or a material serving as a sintering aid on each high-pressure boron nitride powder particle. It is strongly desired to produce a high-pressure boron nitride sintered body.
[0004]
There are various coating methods such as a vapor phase method and a wet plating method. Among them, the vapor phase method is, in principle, (1) easy to control the atmosphere, (2) basically binding material and / or Or, there are no restrictions on the selection of materials as sintering aids, and various types of materials such as active metals and other simple metal materials, nitrides, carbides, borides and oxides can be coated. (3) Bonding Other coating methods, such as the ability to coat the target substance with high purity as a material and / or sintering aid, and (4) the amount of coating of the substance that becomes the binder and / or the substance that becomes the sintering aid can be arbitrarily controlled There are significant advantages that cannot be achieved.
However, the coating of the substance serving as a binder and / or the substance serving as a sintering aid on the high-pressure boron nitride powder particles by the vapor phase method is performed when the high-pressure boron nitride powder particles are fine particles or mainly fine particles. In the case of particles composed of the above, it was impossible to coat the individual high-pressure boron nitride powder particles for the following reason.
That is, when the high-pressure boron nitride powder particles to be coated are fine particles, the core particle powder particles to be coated or the core particle powder particles mainly composed of fine particles are powder particles. Because of its strong adhesion, the cohesiveness is high, and most single particles form aggregates. Since this agglomerate cannot be broken and broken unless a special action exceeding its agglomeration force is applied, even if the agglomerate is coated as it is, a binding material and / or a sintering aid on the surface of each individual particle are used. Coating with an agent is impossible, and as a result, a coated aggregate in which the surface of the aggregate is coated with a binder and / or a sintering aid is formed.
As a result, the individual high-pressure boron nitride particles forming the aggregates are not covered with the particles located inside the aggregates, although the particles on the surface of the aggregates have a large coating amount, but the coating is uneven. There was a problem.
[0005]
In order to solve the above problem, when the high-pressure boron nitride core particle powder particles to be coated are fine particles, the core particle powder particles to be coated or the individual core particle powders mainly composed of the fine particles There have already been attempts to disperse and coat the particles for the purpose of coating the particles.
For example, according to the apparatus and method disclosed in Japanese Patent Application Laid-Open No. 58-31076, core powder particles are placed in a container installed in a PVD apparatus, and the container is vibrated by an electromagnetic method. Then, the core particles in the container are coated by the PVD method while rolling. Further, according to the apparatus disclosed in Japanese Patent Application Laid-Open No. 61-30663, the core powder particles are put into a container installed in the PVD apparatus, and the container is vibrated by a mechanical method. The core particles in the container are covered by the PVD method while rolling. However, in the apparatus or method for coating while rolling the particles of the core particle powder by the vibration of these containers, the particles of the core particle powder or the core particle powder mainly composed of fine particles are actually used. Since it is not possible to apply an action that exceeds the agglomeration force required to break up an aggregate of certain high-pressure boron nitride powder particles, this agglomerate cannot be destroyed, and rather a granulation function is activated before it is introduced into the container. Only more or larger aggregates were formed.
[0006]
In the apparatus and method disclosed in JP-A-3-153864, particles are placed in a rotating container having a barrier and / or irregularities on the inner surface, and the core particle surface is coated by vapor deposition while rotating the rotating container. In such an apparatus or method, high-pressure boron nitride powder particles, which are fine core particle powder particles or core particle powder particles mainly composed of fine particles, are used. Since the action exceeding the cohesive force required to break up the aggregates of the particles cannot be applied, not only the aggregates can be broken, but also more or larger aggregates are formed.
In Japanese Patent Laid-Open No. 58-141375, a powder placed in a reaction gas atmosphere is suspended by the flow of reaction gas and the action of gravity, and the powder is formed by a precipitate generated by a chemical reaction of the reaction gas. An apparatus for coating the surface of the is disclosed. Japanese Patent Application Laid-Open No. 2-43377 discloses a method of performing coating by performing a thermochemical reaction process while fluidizing fine particles under reduced pressure. In the apparatus or method using the fluidized bed by these air currents, each of the high-pressure boron nitride powder particles, which are the particles of the fine particle core particle powder or the core particle powder mainly composed of fine particles, is fluidized. However, the agglomerates of high-pressure boron nitride powder particles could not be broken.
[0007]
Japanese Patent Application Laid-Open No. 54-153789 discloses an apparatus for covering a metal by dropping a powder material in a vacuum vessel in which a metal vapor is generated. Japanese Patent Laid-Open No. 60-47004 discloses a method in which a monomer gas and powder particles are introduced into a high-frequency plasma region in a vacuum chamber and an organic coating film is formed by plasma polymerization. As in these apparatuses or methods, the aggregates of the high-pressure boron nitride powder particles, which are the particles of the fine particle core particle powder or the core particle powder mainly composed of the fine particles, cannot be broken by simply introducing them.
Japanese Patent Application Laid-Open No. 64-80437 discloses a method of breaking and fluidizing an agglomerate of core particle powder with a low-frequency and high-frequency synthesized sound wave. However, in this method of applying vibration to the fluidized bed, agglomerates of high-pressure boron nitride powder particles, which are fine particle core particle powder particles or core particle powder particles mainly composed of fine particles, cannot be destroyed.
[0008]
In Japanese Patent Laid-Open No. Sho 62-250172, as a pretreatment, the powder that has been jet milled is retained in a reduced pressure heat treatment chamber, subjected to heat treatment, and then spontaneously dropped into a sputtering chamber by a powder feeder. An apparatus and a method for introducing and covering a target by allowing it to fall naturally into a cylindrical sputtering chamber provided vertically are disclosed. In JP-A-2-153068, a powder that has been jet milled as a pretreatment is retained in a reduced pressure heat treatment chamber. After the heat treatment is performed, a sputtering source in the sputtering chamber is stored in a powder feeder. An apparatus and method are disclosed in which powder is introduced into a rotating container and sputtering is performed while the container is rotated. In these apparatuses, the powder is temporarily dispersed only at that time by the jet mill treatment, but this powder is retained in the heating step before coating. Even if it is temporarily dispersed in the primary particle state, it re-aggregates due to the retention of this powder in the heating process, and eventually remains agglomerated when introduced into the coating process.
As described above, in all of the above, there is a problem as an apparatus or a method for coating high-pressure boron nitride powder particles, which are fine particle core particle powder particles or core particle powder particles mainly composed of fine particles. No solution has been made, and therefore, each high-pressure boron nitride powder particle is uniformly coated by a vapor phase coating method using a substance serving as a binder and / or a substance serving as a sintering aid as a coating-forming substance. The coated high-pressure boron nitride powder particles could not be produced.
[0009]
[Problems to be solved by the invention]
Therefore, in reality, high-pressure boron nitride powder particles to be coated, particles having an average particle diameter of 10 μm or less, particles of fine particle core particle powder or particles of core particle powder mainly composed of fine particles High-performance high-pressure boron nitride sintered body with coated high-pressure boron nitride powder particles in which a substance serving as a binder and / or a material serving as a sintering aid is coated as a coating-forming substance in a single particle unit And the elucidation of the manufacturing method is strongly demanded.
The present invention relates to a substance and / or a sintering aid as a binder in a single particle unit to fine-particle core particle powder particles or high-pressure boron nitride powder particles which are core particle powder particles mainly composed of fine particles. Uniform, dense, and strongly sintered high-performance high-pressure boron nitride sintered body having a highly controlled microstructure and coated with high-pressure boron nitride particles coated with the material to be coated The object is to provide a manufacturing method.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventor has conducted extensive research, and as a result, high-pressure nitriding in which particles of fine particle core particle powder or core particle powder mainly composed of fine particles is particles of high-pressure boron nitride powder. In order to coat a boron powder particle with a substance serving as a binder and / or a substance serving as a sintering aid as a coating forming substance in a single particle unit, core particles having a volume-based frequency distribution and an average particle diameter of 10 μm or less A highly dispersed state in which the particles of the core particle powder in the gas mixture of the highly dispersed core particle powder in which the powder particles are mainly present in the air in a single particle state have a dispersity β of 70% or more It was found that the coating had to be started at the coating start area of the coating space.
[0011]
More specifically, (I) the core particle powder in which the particles of the high-pressure boron nitride powder are dispersed in the state of a particle / gas mixture of a highly dispersed core particle powder mainly existing in the air in a single particle state. Even if the particles are not retained, they tend to re-aggregate over time due to Brownian aggregation, turbulent aggregation, sonic aggregation, etc. Once re-agglomerated, they must be dispersed by a dispersion processing means having a particularly high dispersion performance. Therefore, it is difficult to re-disperse by breaking the re-aggregation state. For this reason, the particles of the core particle powder having an average particle size of 10 μm or less in the volume-based frequency distribution are mainly in a single particle state. It is necessary to guide the core particle powder particles in the highly dispersed core particle powder / gas mixture present to the coating start region of the coating space in a highly dispersed state with a dispersity β of 70% or more, and To that end, (II) the core particle powder particles From one or more, disintegrating the agglomerates consisting of and dispersing the core particle powder particles in the highly dispersed core particle powder / gas mixture mainly in the air in a single particle state into a highly dispersed state The present inventors have found that there is a need for a dispersion processing means group having a particularly high dispersion performance.
The coated high-pressure boron nitride powder particles or the mixture containing the particles thus obtained are sintered at an ultrahigh pressure and high temperature of 2000 MPa or more, so that they are uniform, dense, and strong. As a result, a high-performance coated high-pressure boron nitride sintered body with a highly controlled microstructure was obtained.
[0012]
That is, the present invention relates to core particle powder particles made of high-pressure boron nitride fine particles, or core particle powder particles mainly made of the same fine particles, the surface of which is coated with a coating-forming substance. When manufacturing a sintered body of high-pressure boron nitride by sintering, the high-pressure boron nitride particles coated with this coating-forming substance are coated by forming a core particle powder into the coating space and passing through the gas phase. The surface of the core particle powder particles is coated with the coating forming material by bringing the forming material precursor and / or the coating forming material precursor in the gas phase into contact with and / or colliding with the particles of the core particle powder. Because
(A) The final treatment means of the fine particle high dispersion treatment means group is:
(A) a dispersing means for dispersing the particles of the core particle powder in the air; and
(B) In the mixture of the core particle powder particles and the gas in which the core particle powder particles are dispersed in the air, the low dispersion core particle powder portion is separated, and the core particle powder particles are mainly single. Highly dispersed core particle powder particle / gas mixture selecting means for selecting a highly dispersed core particle powder particle / gas mixture existing in the air in the particle state, and this highly dispersed core particle powder particle / gas mixture selecting means High dispersion having a low dispersion core particle powder part selectively separated by the above-mentioned dispersion means in the fine particle high dispersion treatment means group and a feedback means for conveying to the treatment means before the final dispersion means. Core particle powder particle / gas mixture selection means,
By means of a group of finely dispersed fine particles selected from the above, particles of a fine particle core particle powder having an average particle diameter of 10 μm or less in a volume-based frequency distribution or core particle powder particles mainly composed of fine particles are dispersed in the air. A dispersion process for making a highly dispersed core particle powder / gas mixture,
(B) The particles of the core particle powder dispersed in this dispersion step are brought into contact with and / or collided with the coating forming material precursor in the coating start region of the coating space in a dispersed state with a dispersion degree β of 70% or more. Coating process to start coating,
Using the one prepared by the coating means consisting of
Provided is a method for producing a coated high-pressure boron nitride sintered body characterized by sintering the coated high-pressure boron nitride particles or a mixture containing the particles at a pressure of 2000 MPa or more and at a high temperature. is there.
[0013]
Furthermore, the present invention provides a method for producing a high-pressure boron nitride sintered body as described above, wherein the high-pressure boron nitride particles coated with a coating-forming substance are:
Coated high-pressure boron nitride for crushing and / or crushing agglomerates of coated high-pressure boron nitride particles that have formed agglomerates in contact via a coating-forming substance of coated high-pressure boron nitride particles Crushing and crushing process of particle aggregates and / or
A selective separation step for selectively separating the high-pressure boron nitride particle agglomerates covered with the high-pressure boron nitride particles coated with primary particles.
In addition, the coated high-pressure boron nitride particles or a mixture containing the particles is sintered at a pressure of 2000 MPa or higher and at a high temperature. Related.
[0014]
Further, according to the present invention, in the above-described method for producing a high-pressure boron nitride sintered body, the core particle powder particles composed mainly of high-pressure boron nitride fine particles whose surface is to be coated with a coating forming material, or mainly from the same particles. The core particle powder particles are coated with one or more coating materials derived from the immersion method by the immersion method using a molten salt bath, or the core particle powder particles mainly composed of fine particles. The high-pressure boron nitride particles coated with the coating-forming substance or a mixture containing the particles are sintered at a pressure of 2000 MPa or higher and a high temperature. Also related to manufacturing methods.
The present invention also provides the above-described coated high-pressure boron nitride in (A) a thermodynamically stable region of high-pressure boron nitride and / or (B) a dynamic and / or static ultrahigh pressure of 2000 MPa or higher. The present invention also relates to a method for producing a sintered body by sintering at a high temperature.
[0015]
Furthermore, the present invention provides a method for producing a high-pressure boron nitride sintered body as described above, wherein the high-pressure boron nitride particles coated with the coating-forming substance have a volume particle frequency distribution and an average particle diameter of 10 μm or less. Is dispersed in the air by the final treatment of the fine particle high dispersion treatment means group to obtain a particle / gas mixture of the highly dispersed core particle powder, and the dispersion β of the core particle powder particles is set to 70% or more. A dispersion step is performed by the fine particle high dispersion treatment unit group having performance, and the particle / gas mixture of the highly dispersed core particle powder dispersed by the fine particle high dispersion treatment unit group is directly discharged to the coating step, or the dispersion step and the coating step An intermediate member composed of a hollow member and a member that forms a hollow, which is inevitable for conveyance, from a discharge part that discharges a particle / gas mixture of the highly dispersed core particle powder dispersed by the fine particle high dispersion processing means group during the process. , And And / or the particles in the gas mixture of the highly dispersed core particle powder that is conveyed through one or more members selected from the pipe and / or dispersed in the air with the above dispersion performance. Air dispersion maintaining means for maintaining an intermediate dispersion state, air dispersion promoting means for enhancing the air dispersion state of particles in a particle / gas mixture of a highly dispersed core particle powder dispersed in the air with the above dispersion performance, and a core Highly dispersed core particle powder in which the low-dispersion core particle powder part of the mixture of particles and gas in the particle powder is separated, and the core particle powder particles are mainly present in the air in a single particle state. The high-pressure boron nitride particles coated with the high-pressure type boron nitride particles are prepared by being conveyed through one or more of the particle / gas mixture selection means of the highly dispersed core particle powder for selecting the particles / gas mixture of Or a mixture containing the same particles at a pressure of 2000 MPa or more, and The present invention also relates to a method for producing the sintered body that is sintered at a high temperature.
[0016]
Furthermore, the present invention provides a method for producing a high-pressure boron nitride sintered body as described above, wherein the high-pressure boron nitride particles coated with the coating-forming substance have a volume particle frequency distribution and an average particle diameter of 10 μm or less. Is dispersed in the air by the final treatment of the fine particle high dispersion treatment means group to obtain a particle / gas mixture of the highly dispersed core particle powder, and the dispersion β of the core particle powder particles is set to 70% or more. It is prepared by carrying out at least a part of the dispersion process by the fine particle high dispersion treatment means group having performance and a part or more of the coating process by sharing a part or more of the space. The present invention also relates to a method for producing the above sintered body, in which high-pressure boron nitride particles or a mixture containing the same is sintered at a pressure of 2000 MPa or more and at a high temperature.
[0017]
Furthermore, the present invention provides a method for producing a high-pressure boron nitride sintered body as described above, wherein the high-pressure boron nitride particles coated with the coating-forming substance have a volume particle frequency distribution and an average particle diameter of 10 μm or less. The body is dispersed in the air by the final treatment of the fine particle high dispersion treatment means group to obtain a particle / gas mixture of the highly dispersed core particle powder, and the dispersity β of the particles of the core particle powder is set to 70% or more. Position the coating start region of the coating space in the spatial region including the surface through which all the particles of the core particle powder in the highly dispersed core particle powder / gas mixture pass. Alternatively, a core particle powder having a volume-based frequency distribution and an average particle diameter of 10 μm or less is dispersed in the air by the final treatment of the fine particle high dispersion treatment means group to obtain a particle / gas mixture of the highly dispersed core particle powder. Core particle powder particle dispersity β is 70% It is prepared by positioning the coating start region of the coating space in the spatial region including the surface through which all the particles collected in the collecting part of the collecting means pass among the spatial region to be above, and this The present invention also relates to a method for producing the above sintered body, in which the coated high-pressure boron nitride particles or a mixture containing the particles is sintered at a pressure of 2000 MPa or more and at a high temperature.
[0018]
Furthermore, the present invention provides a method for producing a high-pressure boron nitride sintered body as described above, wherein the high-pressure boron nitride particles coated with the coating forming material have a particle size distribution and an average particle diameter of D._MIn the volume-based frequency distribution ([D_M/ 5,5D_M], ≧ 90%) is prepared by coating the core particle powder with a coating-forming substance, and the coated high-pressure boron nitride particles or a mixture containing the same is mixed with 2000 MPa or more. The present invention also relates to a method for producing the sintered body that is sintered at a pressure and at a high temperature.
The present invention also relates to a coated high-pressure boron nitride sintered body produced by the production method described above.
[0019]
Thus, according to the present invention, the core particle powder particles made of high-pressure boron nitride fine particles or the core particle powder particles mainly made of the same fine particles, the surface of which is coated with a coating forming substance. When the sintered body is sintered at a pressure of 2000 MPa or higher and at a high temperature to produce a sintered body of high-pressure boron nitride particles, the high-pressure boron nitride particles whose surface is coated with a coating-forming substance are An average particle diameter of 10 μm dispersed in the air by the final processing means of the coating forming material precursor and / or the coating forming material precursor in the gas phase state generated through the gas phase by the phase method and the fine particle high dispersion processing means group The particle / gas mixture of the highly dispersed core particle powder comprising the following fine particles is dispersed in the coating start region of the coating space, and the degree of dispersion of the core particle powder particles in the highly dispersed core particle powder / gas mixture is In a dispersion state where β ≧ 70% The surface of the high-pressure type boron nitride particles coated with a coating-forming material by flowing, contacting and / or colliding is used to obtain an unsintered portion of the surface of the high-pressure type boron nitride particles which has not been obtained so far. It was possible to obtain a high-performance high-pressure boron nitride sintered body having a highly controlled microstructure that was uniform, dense, and strongly sintered. When preparing the above-described coated core particles, the coating-forming material precursor was in a gas phase state composed of atoms, molecules, ions, clusters, atomic clusters, molecular clusters, cluster ions, etc., and the region was generated through the gas phase. However, by starting contact and / or collision with the highly dispersed core particles, the coating-forming substance is firmly bonded to the surface of the individual core particles in the primary particle state. Thus, it is possible to produce coated high-pressure boron nitride particles coated with a coating-forming substance on a single particle basis.
[0020]
Before describing the present invention in detail below, the terms used in this specification will be defined first, and the specific contents of the terms will be explained if necessary, and then the high-pressure type coated with a coating-forming material. An explanation will be given of what technical means the boron nitride particles are prepared by.
[0021]
Coated high-pressure boron nitride particles
The coated high-pressure boron nitride particles refer to the following high-pressure boron nitride particles that have been coated. For example, specifically, the coating-forming substance is coated with high-pressure boron nitride particles as core particles in one or more forms such as ultrafine particles, islands, continuous materials, uniform films, and protrusions. Particles.
[0022]
High-pressure boron nitride raw material powder particles
According to the present invention, the surface of the high-pressure boron nitride core particles, in which the high-pressure boron nitride powder particles are particles of a fine particle core particle powder or a core particle powder mainly composed of fine particles, is coated with a coating forming material. The raw powder particles of the high-pressure boron nitride particles for the coated high-pressure boron nitride particles include artificial high-pressure boron nitride particles that are static and / or dynamic ultrahigh-pressure synthesis and / or low-pressure gas phase methods. Cubic and / or wurtzite boron nitride particles by synthesis can be used.
[0023]
As high-pressure boron nitride raw material powder particles for producing a high-performance coated high-pressure boron nitride sintered body, high-pressure boron nitride particles having a particle diameter of 10 μm or less are used. Specifically, the high-pressure boron nitride particles have an average particle diameter D_MIs 10 μm or less and the volume frequency distribution is ([D_M/ 5,5D_M] ≧ 90%) high-pressure boron nitride powder particles are generally available and can be applied. Average particle size D with a relatively narrow distribution depending on the application_MIs 10 μm or less and the volume-based frequency distribution is ([D_M/ 3,3D_M,> 90%) high-pressure boron nitride powder particles, or the particle diameter of high-pressure boron nitride particles is controlled by classification or the like, and the average particle diameter D having a narrower distribution range_MIs 10 μm or less and the volume-based frequency distribution is ([D_M/ 2,3D_M/ 2], ≧ 90%) high-pressure boron nitride powder particles can be selected.
When the high-pressure boron nitride particles having such a distribution are applied as raw material powder particles, the surface of the high-pressure boron nitride particles in the coated high-pressure boron nitride sintered body is uniform, dense and strong without any unsintered portions. A high performance coated high-pressure boron nitride sintered body having a highly controlled microstructure can be produced.
The coated high-pressure boron nitride sintered body according to the present invention comprises a coated high-pressure boron nitride particle coated with a coating-forming substance on the surface of the high-pressure boron nitride powder particles or a mixture containing the particles of 2000 MPa or more. This is a coated high-pressure boron nitride sintered body containing high-pressure boron nitride particles obtained by sintering at an ultrahigh pressure and high temperature.
[0024]
Gas phase coating method
The vapor phase coating method is a method in which the raw material of the coating forming material is coated at least once through a gas phase state consisting of one or more of molecular flow, ion flow, plasma, gas, vapor, and aerosol, or coating in a gas phase state A method of coating with the raw material of the forming substance.
[0025]
Core particles
A core particle means the particle | grain used as the target object which coat | covers. This is also referred to as matrix particles, seed particles or coated particles.
The core particles are made of high-pressure boron nitride particles, specifically cubic boron nitride particles and / or wurtzite boron nitride particles.
[0026]
Core particle powder
The core particle powder refers to a powder composed of core particles. The particles of the core particle powder are particles constituting the core particle powder. The particles of the fine particle core particle powder used for the coating used in the present invention or the core particle powder mainly composed of fine particles have an average particle size of 10 μm or less in a volume-based frequency distribution.
Preferably, the average particle size is D_MD_MIs 10 μm or less and the particle size distribution is a volume-based frequency distribution ([D_M/ 5,5D_M] ≧ 90%). In such a powder having a relatively narrow distribution, the dispersion characteristics or aggregation characteristics of the powder are characterized by the average particle diameter, and D_MDispersion can be achieved by operating the fine particle high dispersion treatment means group under conditions suitable for the above value.
For powders with a core particle powder having an average particle size of 10 μm or less in a wide particle size distribution or a distribution having a plurality of peaks separated from each other, an appropriate selective separation process such as a classification process is preferably performed. A coating treatment is performed on each classified powder. As a result, for each of the classified powders, coating is started in the coating start region of the coating space with a dispersity β of 70% or more under the above conditions, and each particle of the core particle powder Can be coated.
[0027]
Coating material
A coating forming substance refers to a substance that forms a coating on an object to be coated. For example, it specifically refers to a substance that forms a coating on the particles of the core particle powder in the form of one or more of ultrafine particles, islands, continuous material, uniform film, protrusions, and the like.
In particular, when the form of the coating forming substance is ultrafine particles, the particle diameter of the ultrafine particles is, for example, in the range of 0.005 μm to 0.5 μm.
The coating-forming material is formed by coating the coating-forming material itself as it is, or when the coating-forming material reacts with the high-pressure boron nitride of the core particle and / or dissolves in the high-pressure boron nitride particles. One or more of the desired inorganic compounds, alloys, intermetallic compounds, etc. for reacting and / or alloying and / or forming a solid solution with two or more kinds of coating forming substances A simple substance and / or a compound and / or a surface modifier for the high-pressure boron nitride particles that produce the above and become sintering aids and / or binders that promote the sintering of the coated high-pressure boron nitride particles. Selected from substances and / or compounds.
[0028]
That is, a coating forming material can be selected as a surface modifier that controls the grain boundaries of the high-pressure boron nitride particles. If necessary, for example, the chemical bond between the high-pressure type boron nitride particles and the binder and / or sintering aid is increased, or the individual high-pressure type boron nitride particles are isolated from an arbitrary substance, whereby the high-pressure type boron nitride particles are separated. It is necessary to suppress the reaction between boron nitride and any substance, or to select sintering conditions in which the pressure is 2000 MPa or more and the high pressure boron nitride is thermodynamically metastable. In this case, the phase transition to the graphite type phase can be suppressed. Thereby, the range of selection of the coating forming material as the binder and / or sintering aid is greatly widened, which is preferable.
[0029]
These coating-forming substances are periodic table 1a, 2a, 3a, 4a, 5a, 6a, 7a, 1b, 2b, 3b, 4b, 5b, 6b, 7b, group 8 metal, semiconductor, semimetal, rare earth metal , One or more non-metals and oxides thereof, nitrides, carbides, oxynitrides, oxycarbides, carbonitrides, oxycarbonitrides, borides, silicides, such as Al, B, Si, Fe, Ni, Co, Ti, Nb, V, Zr, Hf, Ta, W, Re, Cr, Cu, Mo, Y, La, TiAl, Ti_ThreeAl, TiAl_Three, TiNi, NiAl, Ni_ThreeAl, SiC, TiC, ZrC, B_FourC, WC, W₂C, HfC, VC, TaC, Ta₂C, NbC, Mo₂C, Cr_ThreeC₂, Si_ThreeN_Four, TiN, ZrN, Si₂N₂O, AlN, HfN, VxN (x = 1 to 3), NbN, TaN, Ta₂N, TiB, TiB₂, ZrB₂, VB, V_ThreeB₂, VB₂, NbB, NbB₂, TaB, TaB₂, MoB, MoB₂, MoB_Four, Mo₂B, WB, W₂B, W₂B_Five, LaB₆, B₁₃P₂, MoSi₂, BP, Al₂O_Three, ZrO₂, MgAl₂O_Four(Spinel), Al₂SiO_FiveIt can be a material containing one or more of (mullite).
The amount of the coating-forming substance added by coating can be selected from a trace amount to a large amount.
[0030]
Definition of input to cladding space
The introduction into the coating space refers to introducing the core particle powder into the coating space by, for example, a free fall or the like. When the carrier gas is used, the core particle powder is introduced in the direction of the flow of the particle / gas mixture of the core particle powder, or the gas is put on the gas in the direction of the flow or the direction of the gas is changed. It means to be introduced. Or it refers to introducing under the action of carrier gas. For example, it may be introduced by the wave phenomenon of the carrier gas, specifically, non-linear wave. Alternatively, it may be introduced into the coating space by a sound wave, an ultrasonic wave, a magnetic field, an electron beam or the like in a gas. It also means introducing by an external field such as an electric field, a magnetic field, or an electron beam. Specifically, it means charging the powder particles with an electric field, magnetic field, electron beam or the like, or magnetizing them and introducing them into the coating space by attractive force or repulsive force. In addition, it includes suction and introduction by back pressure or decompression of gas.
[0031]
Covered space
The coating space is a space in which the coating forming material precursor generated from the raw material of the coating forming material through the gas phase and / or the coating forming material precursor in the gas phase and the particles of the core particle powder contact and / or collide with each other. Say. Or the space area | region which coat | covers the surface of the particle | grains of core particle powder with a coating forming substance.
Coating chamber
The coating chamber refers to a chamber having a part or more of the coating space. More specifically, the coating chamber is a partitioned or substantially partitioned (substantially closed or semi-closed) chamber including the coating space and including a part or more of the coating space.
In the air
“Air” refers to a space in a vacuum or gas phase. Here, in the present invention, the gas phase state refers to a state of molecular flow, ion flow, plasma, gas, vapor or the like. Technically, vacuum means a reduced pressure state. Strictly speaking, gases, molecules, atoms, ions, etc. are included under any reduced pressure.
[0032]
Coating material precursor
A coating-forming material precursor is a precursor of a coating-forming material. More specifically, the coating material is formed on and / or synthesized from the raw material of the coating-forming material in the vapor phase as it is or through the vapor phase from the raw material of the coating-forming material, and the coating is formed on the core particles that are particles to be coated. The substance up to just before. The coating forming material precursor is not limited in state as long as it is formed and / or synthesized from the raw material of the coating forming material via the gas phase. When the raw material of the coating forming material is in the gas phase, this raw material can also be a coating forming material precursor. The coating-forming material precursor itself may be in the gas phase. Further, when the coating forming material precursor is a reactive material, it may be before the reaction, during the reaction, or after the reaction. Specific examples of the coating forming material precursor include ions, atoms, molecules, clusters, atomic clusters, molecular clusters, cluster ions, ultrafine particles, gas, vapor, and aerosol.
Raw material for coating forming materials
The raw material of the coating forming substance refers to a raw material substance that becomes a substance that forms a coating through a gas phase. Specific examples of the form of the raw material for the coating-forming substance include massive solids, powder particles, gas, and liquid.
[0033]
Dispersion β
The dispersity β is an index for evaluating the dispersion performance of a powder dispersion apparatus as proposed by Masuda and Goto et al. (See Chemical Engineering, 22nd Autumn Meeting Presentation, P349 (1989)). , Defined as the ratio of the weight of the particles in the apparent primary particle state to the weight of the total particles. Here, the apparent primary particle state is a mass-based frequency distribution f of powder particles in an arbitrary dispersion state._m2And the mass-based frequency distribution of completely dispersed powder particles f_m1The ratio of the overlapping parts of the following is expressed by β in the following formula.
[0034]
[Expression 1]

In the above formula, the unit of particle diameter (μm) is not specified.
The above formula evaluates the degree of dispersion based on the particle size distribution expressed on a mass basis. Originally, the degree of dispersion should be evaluated based on the particle size distribution expressed on a volume basis. When the powder particle density is the same, the particle size distribution expressed by mass and the particle size distribution expressed by volume are the same. Therefore, a mass-based particle size distribution that is practically easy to measure is measured and used as a volume-based particle size distribution. Therefore, the original degree of dispersion β is expressed by the following equation and the area of the shaded portion in FIG.
[0035]
[Expression 2]

In the above formula, the unit of particle diameter (μm) is not specified.
The distribution of the core particle powder and the average particle diameter are basically based on volume unless otherwise specified.
[0036]
Volume-based frequency distribution
Volume-based frequency distribution refers to a distribution of particle diameters expressed as a volume ratio included in a certain particle diameter.
([D₁, D₂], ≧ 90%)
([D₁, D₂], ≧ 90%) distribution is D₁, D₂Is the particle diameter, D₁<D₂D₁D₂The following particles represent a distribution containing 90% or more by volume, and a powder composed of particles having a hatched portion of 90% or more as shown in FIG. 1 (b).
[0037]
Volume-based frequency distribution ([D_M/ 5,5D_M], ≧ 90%)
The particle size distribution is a volume-based frequency distribution (([D_M/ 5,5D_M], ≧ 90%) distribution is D_MIs the volume-based average particle size, D_MMore than 1/5 times the particle diameter, D_MRepresents a distribution containing 90% or more by volume of particles having a particle size of 5 times or less. For example, average particle diameter D_MIs 5 μm and the volume-based frequency distribution is ([D_M/ 5,5D_M], ≧ 90%) represents a distribution in which the volume-based average particle diameter is 5 μm, and particles having a particle diameter of 1 μm or more and 25 μm or less are contained by 90% or more by volume. Here, the volume-based average particle diameter D_MIs
[Equation 3]

Or technically, a certain particle size interval is D_i± △ D_i/ 2 (△ D_iIs the volume of the particles within the section width)_iThen,
D_M= Σ (v_iD_i) / Σv_i
It is expressed.
[0038]
Covering start area
A region where coating is started for the first time after the final processing of the fine particle high dispersion processing means group is referred to as a coating start region. Therefore, even before the final treatment of the fine particle high dispersion treatment means group, even the region where the coating is started for the first time is not the coating start region here.
[0039]
Dispersion β in the coating start region
In the present invention, a core particle powder having a volume-based frequency distribution and an average particle diameter of 10 μm or less is dispersed in the air by the final treatment of the fine particle high dispersion treatment means group to obtain a particle / gas mixture of the highly dispersed core particle powder. A coating chamber is provided in which the coating start region of the coating space is positioned in a region where the dispersion degree β of the core particle powder is 70% or more. If the dispersity is in the coating start region of the coating space, particles of the core particle powder having an average particle diameter of 10 μm or less in a volume-based frequency distribution or core particle powder particles mainly composed of particles are substantially At least a part of the surface of all the core particle powder particles passing through the coating start area of the coating space, and the coating forming material precursor. Since it contacts and / or collides with each other, it is always possible to attach a coating forming substance to each unit of particles.
Preferably, in the coating start area of the coating space, the core particle powder having an average particle diameter of 10 μm or less with a volume-based frequency distribution is dispersed in the air by the final dispersion treatment of the fine particle high dispersion treatment means group to achieve high dispersion. A particle / gas mixture of the core particle powder is used, and the degree of dispersion β of the core particle powder is 80% or more. If the degree of dispersion in the coating start region of this coating space, the core particle powder is a core particle powder consisting mainly of fine particles or particles of a fine particle core particle having a volume-based frequency distribution and an average particle size of 10 μm or less. The core particles are virtually closed by the core particles, and the coating-forming material precursor can be contacted and / or collided everywhere on the surface of each particle. The particle surface can be coated almost uniformly.
[0040]
More preferably, in the coating start region of the coating space, the core particle powder having an average particle size of 10 μm or less with a volume-based frequency distribution is dispersed in the air by the final dispersion treatment of the fine particle high dispersion treatment means group to increase the particle size. A dispersed core particle powder particle / gas mixture is used, and the dispersion degree β of the core particle powder particles is 90% or more. If the degree of dispersion of the coating start area of this coating space is the core particle powder, the core particle powder is composed mainly of fine particles having a volume-based frequency distribution and an average particle size of 10 μm or less. Even body particles are virtually non-agglomerated and can be coated virtually uniformly on the surface of each individual particle.
In particular, since the processing efficiency may be low, the degree of dispersion is more preferably 95% or more when high-quality coating is desired. In this case, it is possible to process a small amount of the core particle powder particles to reduce the number concentration in the air of the completely dispersed core particle powder particles. As a result, the entire surface of each particle can be uniformly coated.
[0041]
Fine particle high dispersion treatment means
Fine particle high dispersion treatment means group
(A) having at least one dispersing means,
(B) As the final processing means,
(A) a dispersing means for dispersing the particles of the core particle powder in the air, or
(B) In the mixture of the core particle powder particles and the gas in which the core particle powder particles are dispersed in the air, the low dispersion core particle powder portion is separated, and the core particle powder particles are mainly single. Highly dispersed core particle powder particle / gas mixture selecting means for selecting a highly dispersed core particle powder particle / gas mixture existing in the air in the particle state, and this highly dispersed core particle powder particle / gas mixture selecting means High dispersion having a low dispersion core particle powder portion separated by the above-mentioned dispersion means in the fine particle high dispersion treatment means group and a feedback means for conveying to the treatment means before the final dispersion means. Core particle powder particle / gas mixture selection means,
It is what has.
Preferably, a core particle powder having a volume-based frequency distribution and an average particle diameter of 10 μm or less is dispersed in the air by the final treatment of the fine particle high dispersion treatment means group to obtain a particle / gas mixture of the highly dispersed core particle powder, The core particle powder has a dispersion performance such that the particle dispersity β is 70% or more.
Corresponding to various dispersion degrees in the coating start region, for example, β ≧ 80%, 90%, and 95%, by providing a fine particle high dispersion processing means group having a dispersion performance equal to or higher than those, in the coating start region, High quality coating according to the degree of dispersion can be applied.
[0042]
Final processing means
When the final processing means of the fine particle high dispersion processing means group is a dispersion means, this dispersion processing means is called the final processing means of the fine particle high dispersion processing means group. Also, because the final processing means of the fine particle high dispersion processing means group was in the low dispersion state during the particle / gas mixture selection processing step of the highly dispersed core particle powder to the final dispersion means of the fine particle high dispersion processing means. The particle / gas mixture of the highly dispersed core particle powder or the processing means before the final dispersing means is provided with a feedback means for conveying the selectively separated part to the particle / gas mixture. In the case of a highly dispersed core particle powder particle / gas mixture selecting means equipped with a feedback means for conveying a portion selectively separated because it was in a low dispersion state during the mixture selection processing step, this highly dispersed core particle powder This particle / gas mixture selection means is called the final processing means of the fine particle high dispersion processing means group.
In addition, it is provided before the particle / gas mixture selection means of the highly dispersed core particle powder provided with the feedback means which is the final processing means of the fine particle highly dispersed treatment means group (for example, the highly dispersed core particle powder provided with this feedback means. The particle / gas mixture selection means of the highly dispersed core particle powder is a group of fine particle high dispersion treatment means regardless of the presence or absence of the feedback means, between the body particle / gas mixture selection means and the final dispersion means or before the final dispersion means. Is a component of
[0043]
Dispersion means
A means used for dispersing the fine particles is referred to as a dispersing means. Any dispersing means that has a slight or slight dispersion effect can be used as the dispersing means, and this is used as the dispersing means. For example, a rotary feeder or injection feeder for pneumatic transportation generally used as a supply means (powder engineering society edition: “Powder Engineering Handbook”, Nikkan Kogyo Shimbun (1986) P568, P571) also has a dispersion effect. When used as an intended means, it is a dispersion means. The dispersion maintaining / promoting means described later is also a dispersion means when used for the purpose of dispersion (for the purpose of increasing β). The dispersing means may be a single device or device, or may be a combined device or device, and these are collectively referred to as a fine particle high dispersion processing means group.
This fine particle high-dispersion processing means group includes acceleration of the particles of the core particle powder and / or dispersion by an air flow placed in a velocity gradient, collision of the particles of the core particle powder with a stationary obstacle and / or an obstacle that is a rotating body. Of one or more selected dispersions, such as dispersion by pulverization and / or pulsating and / or rotating drum and / or mechanical disintegration consisting of vibration and / or scraping. The one with the mechanism.
[0044]
Specifically, the fine particle high dispersion processing means group includes an ejector-type disperser, a venturi-type disperser, a thin tube, a stirrer, a disperser using obstacles in an air stream, a disperser using jet blowing, a spiral Disperser using tubes, rotating blades, disperser using rotating pins (cage mill), fluidized bed type disperser, disperser using pulsating flow, disperser using rotating drum, disperser using vibration Disperser that uses scraping with a vibration sieve, scraper, SAEI, Gonell disperser, medium strip disperser, Roller disperser, orifice disperser, BM disperser, Timbrell disperser, Wright disperser Dispersing means consisting of one or more selected machines, etc. (Powder Engineering Society: “Powder Engineering Handbook”, Nikkan Kogyo Shimbun (1986) P430).
[0045]
Further, a disperser using a stirring blade described in JP-A No. 56-1336, a disperser using a high-speed air flow and a dispersion nozzle described in JP-A No. 58-163454, and described in JP-A No. 59-199027. Disperser utilizing the dispersing action by the rotating blades and the dispersing action by the plasma ions, the dispersing machine utilizing the dispersing action by the plasma ions described in JP-A-59-207319, and the ejector described in JP-A-59-216616 Disperser using the dispersion action of the plasma ion and the ejector described in JP-A-59-225728, Disperser using the dispersion action of the ion flow, Dispersion action of the plasma ion described in JP-A-59-183845 , A dispersing machine using a dispersing blade and a dispersing action by pressure gas as described in JP-A 63-166421, JP-A 62-1 A disperser using a line or ring-shaped slit-type jet nozzle described in No. 6527, a disperser using mesh blades described in JP-A 63-221829, and an injection nozzle described in JP-A 63-1629 Disperser using a dispersion action by a high-speed air flow from, a disperser using a large number of pores described in Japanese Utility Model Sho 63-9218, an ejector type disperser described in Japanese Utility Model Sho 62-156854, The thing described in the gazettes, such as a disperser using the pore and orifice described in Sho 63-6034, can also be used.
Examples of suitable dispersing means for the fine particle high-dispersion processing means group include apparatuses described in Japanese Patent Application No. 63-131358, Japanese Patent Application No. 1-71071, Japanese Patent Application No. 2-218537.
[0046]
Particle / gas mixture selection means for highly dispersed core particle powder
The particle / gas mixture selection means of the highly dispersed core particle powder is a particle in which the particle / gas mixture of the low dispersion core particle powder is separated from the particle / gas mixture of the core particle powder, and the particles are mainly in a single particle state. Means for selecting a particle / gas mixture of the highly dispersed core particle powder containing. Aggregated particles, which are aggregates of primary particles, can be separated by, for example, dry classification means because the apparent particle size is larger than the particle size of the primary particles. Examples of particle / gas mixture selection means for this highly dispersed core particle powder include classification means using gravity, classification means using inertial force, classification means using centrifugal force, classification means using static electricity, flow One or more dry classification means selected from classification means using a layer, etc. may be mentioned.
Examples of particle / gas mixture selection means for highly dispersed core particle powder include gravity classifier, inertia classifier, centrifugal classifier, cyclone, air separator, micron separator, microplex, multiplex, zigzag classifier, Accucut , Conical separator, Turbo classifier, Super separator, Dispersion separator, Elbow jet, Fluidized bed classifier, Virtual impactor, O-Sepa, Sieve, Vibrating screen, Shifter (Powder Engineering Handbook: “Powder Engineering Handbook” Kogyo Shimbun, P514 (1986)).
[0047]
Core particle powder particle / gas mixture
The core particle powder particle / gas mixture is: (a) a homogeneous flow in which the core particle powder particles are uniformly suspended in the air (uniform floating flow); (b) the core particle powder particles are Inhomogeneous flow (non-homogeneous floating flow) showing non-uniform distribution in a certain region in the air, (c) flow with sliding layer of core particle powder particles (sliding flow), or (d) core A flow with a stationary layer of particles of particulate powder.
[0048]
Low dispersion core particle powder particle / gas mixture
The low-dispersion core particle powder particle / gas mixture is a core particle in which the core particle powder particles are mainly in a state other than a single particle state in the core particle powder particle / gas mixture. A powder particle / gas mixture.
[0049]
Particle / gas mixture of highly dispersed core particle powder
The particle / gas mixture of the highly dispersed core particle powder refers to a particle / gas mixture of the core particle powder in which the particles of the core particle powder mainly exist in the air in a single particle state. The particle / gas mixture of the highly dispersed core particle powder actually contains agglomerated particles even though it is extremely highly dispersed. The particle / gas mixture of the low-dispersion core particle powder actually contains single particles that are not agglomerated, and selectively separates the particles / gas mixture of the low-dispersion core particle powder and the particles of the high-dispersion core particle powder. -Divided into gas mixtures. The particle / gas mixture of the low dispersion core particle powder becomes a particle / gas mixture of the high dispersion core particle powder by selective separation and / or redispersion of the aggregated particles.
[0050]
Collection means
A means for taking out the coated particles coated in the coating space is called a collecting means. The part of the collection means where the collection process is performed is called a collection unit. The coated particles coated through the coating start area of the coating space are directly taken out from the air and collected, or taken out from the air and temporarily stored and then collected, or collected together with the gas.
As a collection unit of the collection unit, a collection unit of the collection unit using a partition wall (obstacle), a collection unit of the collection unit using gravity, a collection unit of the collection unit using inertial force, a collection unit using centrifugal force Recovery unit, recovery unit recovery unit using attractive force due to electrification, recovery unit recovery unit using thermophoretic force, recovery unit recovery unit using Brownian diffusion, suction force due to gas back pressure or decompression, etc. A collection unit or the like of the used collection means can be used.
Preferable examples of the collecting unit of the collecting means include a gravity dust collector, an inertia dust collector, a centrifugal dust collector, a filtration dust collector, an electric dust collector, a cleaning dust collector, a particle packed bed, a cyclone, a bag filter, a ceramic filter, and a scrubber.
[0051]
Next, a group of fine particle high dispersion treatment means employed when preparing the coated high-pressure boron nitride particles used in the present invention will be described with reference to the accompanying drawings.
[0052]
Explanation of diagram of fine particle high dispersion treatment means
FIG. 2 (a) is a block diagram showing an example of a basic configuration of a fine particle high dispersion treatment group when preparing coated high-pressure boron nitride particles. The final dispersion means A for dispersing the particles of the core particle powder, and the component d of the dispersion processing means group before the final dispersion means. ε is a particle / gas mixture of highly dispersed core particle powder that exists in the air mainly in a single particle state among the particles of the core particle powder. As the component d, any treatment means such as a dispersion means, a supply means, a particle / gas mixture selection means of highly dispersed core particle powder can be used alone or in combination. The component d is not necessarily provided.
The fine particle highly-dispersed processing means group preferably has a dispersity β of the dispersity β with respect to the core particle powder having a volume-based frequency distribution and an average particle diameter of 10 μm or less after the processing of the dispersing means A as the final processing means. It is the structure which can implement | achieve 70% or more.
[0053]
FIG. 2B is a block diagram showing a second example of the basic configuration of the fine particle high dispersion treatment means group in preparing the coated high-pressure boron nitride particles. The final dispersion means A for dispersing the particles of the core particle powder, the particles of the highly dispersed core particle powder in which the particles of the core particle powder are mainly present in the air in the final dispersion means A The final high dispersion core particle powder particle / gas mixture selection means B provided with the feedback means C for feeding back the gas / gas mixture η of the low dispersion core particle powder other than the gas mixture, the dispersion before the final dispersion means It comprises a component d of the processing means group and a component e of the fine particle high dispersion processing means group between the final dispersion means and the final selection means. ε is a particle / gas mixture of highly dispersed core particle powder that exists in the air mainly in a single particle state among the particles of the core particle powder. As the component d, any processing means such as a dispersion means, a supply means, a selection means or the like can be used alone or in combination. As the component e, any processing means other than the dispersion means, for example, any processing means such as a supply means and a selection means can be used alone or in combination. The components d and e are not necessarily provided. The fine particle highly dispersed treatment means group is preferably configured such that after the treatment by the selection means B which is the final treatment means, the degree of dispersion of the distribution of the core particle powder can be 70% or more.
[0054]
FIG. 2C is a block diagram showing a third example of the basic configuration of the fine particle high dispersion treatment means group in preparing the coated high-pressure boron nitride particles. Highly dispersed core particles in which the particles of the core particle powder are mainly present in the air in the form of a single particle to the final dispersion means A for dispersing the particles of the core particle powder and the processing means before the final dispersion means A Highly dispersed core particle powder particle / gas mixture selection means B provided with feedback means C for feeding back particles / gas mixture η of low dispersion core particle powder other than powder particles / gas mixture, final dispersion means It consists of a component d of the previous fine particle high dispersion treatment means group and a component e of the fine particle high dispersion treatment means group between the final dispersion means and the last selection means. ε is a particle / gas mixture of highly dispersed core particle powder that exists in the air mainly in a single particle state among the particles of the core particle powder. As the component d, any processing means such as a dispersion means, a supply means, a selection means or the like can be used alone or in combination. As the component d, processing means other than the dispersion means, for example, arbitrary processing means such as supply means and selection means can be used alone or in combination. The components d and e are not necessarily provided. The fine particle highly dispersed treatment means group is preferably configured such that after the treatment by the selection means B which is the final treatment means, the degree of dispersion of the distribution of the core particle powder can be 70% or more.
[0055]
In addition, since it is the above structures, you may also include in the structure of this fine particle highly dispersed process means group powder supply sources, such as a supply tank and a core particle production | generation means. For example, in the case of FIG. 2 (c), it goes without saying that the configuration in which the feedback destination of the feedback means C is the supply tank may be the configuration of the highly dispersed processing means group. Needless to say, a crushing step of crushing and / or crushing the particles of the core particle powder may be inserted before the dispersion step of the fine particle high dispersion treatment means group.
[0056]
A more detailed description will be given based on a more detailed block diagram of a concrete representative example of the basic configuration of the above-described fine particle high dispersion processing means group.
Configuration 1
FIG. 3A is a block diagram for explaining the first configuration of the fine particle high dispersion treatment means group in preparing the coated high-pressure boron nitride particles, and corresponds to FIG. . This example includes a supply tank 100 for supplying core particle powder to be coated, and a final dispersion means A for dispersing the core particle powder to be coated. ε is a particle / gas mixture of highly dispersed core particle powder that exists in the air mainly in a single particle state among the particles of the core particle powder.
[0057]
Configuration 2
FIG. 3B is a block diagram for explaining a second configuration of the fine particle high dispersion processing means group in preparing the coated high-pressure boron nitride particles, and corresponds to FIG. . This example includes a supply tank 100 for supplying the core particle powder to be coated, a dispersion means a for dispersing the core particle powder to be coated, and a final dispersion means A for dispersing the core particle powder to be coated. Yes. ε is a particle / gas mixture of highly dispersed core particle powder that exists in the air mainly in a single particle state among the particles of the core particle powder.
[0058]
Configuration 3
FIG. 3C is a block diagram for explaining a third configuration of the fine particle high dispersion processing means group in preparing the coated high-pressure boron nitride particles, and corresponds to FIG. . In this example, the supply tank 100 for supplying the core particle powder to be coated, the dispersion means a for dispersing the core particle powder to be coated, and the particle / gas mixture of the core particle powder dispersed by the dispersion means a A feedback means C for feeding back the particles / gas mixture η of the low dispersion core particle powder other than the particles / gas mixture of the high dispersion core particle powder mainly existing in the air in a single particle state to the dispersion means a, Highly dispersed core particle powder particle / gas mixture selection means b for mainly introducing a highly dispersed core particle powder particle / gas mixture into the final dispersion means A, and final dispersion means for dispersing the coated core particle powder. A. ε is a particle / gas mixture of highly dispersed core particle powder that exists in the air mainly in a single particle state among the particles of the core particle powder.
[0059]
Configuration 4
FIG. 3 (d) is a block diagram for explaining a fourth configuration of the fine particle high dispersion treatment means group in preparing the coated high-pressure boron nitride particles, and corresponds to FIG. 2 (b). . This example shows a supply tank 100 for supplying coated core particle powder, a final dispersion means A for dispersing the coated core particle powder, and a particle / gas mixture of the core particle powder dispersed by the final dispersion means A. The feedback means for feeding back to the dispersion means A the particles / gas mixture of the highly dispersed core particle powder mainly existing in the air in a single particle state, and the particles / gas mixture η of the low dispersion core particle powder other than C, the final high-dispersion core particle powder particle / gas mixture selection means B for releasing the high-dispersion core particle powder particle / gas mixture. ε is a particle / gas mixture of highly dispersed core particle powder that exists in the air mainly in a single particle state among the particles of the core particle powder.
[0060]
Configuration 5
FIG. 3 (e) is a block diagram for explaining a fifth configuration of the fine particle high dispersion treatment means group in preparing the coated high-pressure boron nitride particles, and corresponds to FIG. 2 (b). . In this example, a supply tank 100 for supplying coated core particle powder, a dispersing means a for dispersing the coated core particle powder, a final dispersing means A for dispersing the coated core particle powder, and a final dispersing means Of the particles / gas mixture of the core particle powder dispersed in A, the particles / gas mixture of the highly dispersed core particle powder mainly existing in the air in a single particle state, The feedback means C feeds back the particle / gas mixture η to the dispersion means A, and the final highly dispersed core particle powder particle / gas mixture selection means B that releases the particle / gas mixture of the highly dispersed core particle powder. Yes. ε is a particle / gas mixture of highly dispersed core particle powder that exists in the air mainly in a single particle state among the particles of the core particle powder.
[0061]
Configuration 6
FIG. 3 (f) is a block diagram for explaining the sixth configuration of the fine particle high dispersion treatment means group in preparing the coated high-pressure boron nitride particles, and corresponds to FIG. 2 (b). . This example mainly removes the particles / gas mixture of the low-dispersion core particle powder from the supply tank 100 for supplying the core particle powder to be coated, and the particle / gas mixture of the core particle powder, and mainly high dispersion. A highly dispersed core particle powder particle / gas mixture selecting means b for introducing the core particle powder particle / gas mixture into the dispersing means A, a final dispersing means A for dispersing the selectively separated core particle powder particles, and a final Low-dispersion core particle powder other than the particles / gas mixture of the highly dispersed core particle powder that exists in the air mainly in a single particle state from the particles / gas mixture of the core particle powder dispersed by the dispersing means A A feedback means C for feeding back the body particle / gas mixture η to the dispersion means A, and a final high dispersion core particle powder particle / gas mixture selection means B for releasing the highly dispersed core particle powder particle / gas mixture. Has been. ε is a particle / gas mixture of highly dispersed core particle powder that exists in the air mainly in a single particle state among the particles of the core particle powder.
[0062]
Configuration 7
FIG. 3 (g) is a block diagram for explaining a seventh configuration of the fine particle high dispersion treatment means group in preparing the coated high-pressure boron nitride particles, and corresponds to FIG. 2 (c). . In this example, a supply tank 100 for supplying coated core particle powder, a dispersing means a for dispersing the coated core particle powder, a final dispersing means A for dispersing the coated core particle powder, and a final dispersing means Of the particles / gas mixture of the core particle powder dispersed in A, the particles / gas mixture of the highly dispersed core particle powder mainly existing in the air in a single particle state, A feedback means C for feeding back the particle / gas mixture η to the dispersion means a, and a final high dispersion core particle powder / gas mixture selection means B for releasing the particle / gas mixture of the highly dispersed core particle powder. Yes. ε is a particle / gas mixture of highly dispersed core particle powder that exists in the air mainly in a single particle state among the particles of the core particle powder.
[0063]
In order to maintain the highly dispersed state of the fine particles thus achieved, an air dispersion maintaining means can be added between the fine particle highly dispersed treatment means group and the coating chamber. The air dispersion maintaining means here means means for preventing the re-aggregation of the particles of the core particle powder dispersed and supported in the air and maintaining the dispersity β. In order to promote the highly dispersed state of the core particles thus achieved, an air dispersion promoting means can be added between the fine particle highly dispersed treatment means group and the coating chamber. Air dispersion promoting means here means mainly promoting the re-dispersion of the re-aggregated particles among the core particle powder particles dispersed and supported in the air, slowing down the dispersion state, or once decreasing Means for promoting re-dispersion so that the dispersed state is restored to the original highly dispersed state.
Preferable examples of the air dispersion maintaining means or the air dispersion promoting means include a pipe vibration device, a pipe heating device, a plasma generator, and a charging device.
[0064]
The pipe vibration device is a means for suppressing reagglomeration and maintaining high dispersion by giving vibrations that cannot be called a disperser to particles dispersed in the air by vibration of the pipe where the oscillator is installed. It is a means for promoting the dispersion of the particles.
The pipe heating device expands the carrier gas by applying heat from the outside of the carrier gas using a heated pipe, accelerates the flow velocity to the extent that it cannot be called a disperser, suppresses reaggregation, and disperses the reaggregated particles. It is a means to promote.
[0065]
The plasma generator generates plasma in the air in which the core particle powder is dispersedly supported, and by means of collision between the plasma ions and the core particles, means for suppressing reaggregation and maintaining a highly dispersed state or reaggregation It is a means for promoting particle dispersion.
The charging device generates monopolar ions in the air carrying the core particle powder in a dispersed manner by means of corona discharge, electron beam, radiation, etc., and passes the particles through a monopolar ion atmosphere so that the particles are monopolar. Or a means for suppressing reaggregation by electrostatic repulsion and maintaining a highly dispersed state, or a means for promoting dispersion of reaggregated particles.
[0066]
The core particle powder in a highly dispersed state of the fine particles thus formed is sent to a coating chamber in order to coat the surface of the particles with a coating forming substance. This coating chamber is provided with a coating space including a coating start region.
It is desirable that the fine particle high dispersion treatment means group and the coating chamber be directly connected, but they may be connected using a hollow member and / or a pipe that are inevitable for conveyance. Also in this case, it is essential to realize β ≧ 70% in the coating start region.
When the fine particle high dispersion treatment means group and the coating chamber are placed separately and connected between them, the core particle powder may be introduced into the coating chamber in its dispersed state. For this purpose, an air dispersion maintaining means and / or an air dispersion promoting means and / or a core particle powder which is an apparatus for maintaining the dispersed state of the core particle powder during this period. Highly dispersed core particle powder particles that separate the low-dispersed core particle powder portion from the particle / gas mixture and select the highly dispersed core particle powder particle / gas mixture mainly containing particles in a single particle state -A gas mixture selection means can also be provided.
[0067]
Also, when preparing coated high-pressure boron nitride particles, the fine particle high dispersion processing means group shares a part or more with (1) the coating chamber, or (2) the coating space, or (3) the coating start region. You can also
For example, a dispersion space and a coating chamber in the fine particle high dispersion means group, a dispersion space in the fine particle dispersion means group and a coating space having a coating start area, or a dispersion space and coating in the fine particle dispersion means group. The starting area can also be shared spatially.
Here, the coating start region is a coating forming material precursor and / or a coating forming material precursor in a gas phase state that is produced through a gas phase on a highly dispersed core particle powder conveyed in a dispersion state of β ≧ 70%. It refers to the region where the body contacts and / or collides and starts covering, and the following modes shown in FIGS. 4 (a) to 4 (e) are considered.
That is, in FIGS. 4A to 4E, the coating start region is a region indicated by 2.
[0068]
In FIG. 4 (a), the coating start region 2 of the coating space where coating is started in a dispersion state of β ≧ 70% with respect to the powder is a part of the fine particle high dispersion processing means group or a part of the fine particle high dispersion processing means group. Preferably, it is provided so as to cover the discharge part 1 of the fine particle high dispersion treatment means group.
In FIG. 4B, the coating starts in the dispersion state of β ≧ 70% through which all the particles 4 of the core particle powder discharged from the discharge part 1 of the fine particle high dispersion processing means group or the fine particle high dispersion processing means group pass. A space covering start area 2 is provided.
With the above configuration, coating of all the core particle powder particles is started in a dispersion state of β ≧ 70%.
In FIG. 4C, among the particles 4 of the core particle powder discharged from the discharge part 1 of the fine particle high dispersion treatment means group or the fine particle high dispersion treatment means group, the particles β entering the collection part 5 always pass through. A coating start area 2 is provided in the coating space where coating is started in a dispersion state of 70%.
[0069]
In FIG. 4D, a coating start region 2 of a coating space that starts coating in the dispersion state of β ≧ 70% surrounding the collection unit 5 is provided.
In FIG. 4E, the recovery unit 5 is provided at a position where only particles of the highly dispersed core particle powder / gas mixture can reach. Accordingly, the region 6 here is a selection means using gravity. The coating start area 2 of the coating space where the coating of the highly dispersed core particle powder particles / gas mixture entering the recovery section starts coating in the dispersion state of β ≧ 70% is provided as shown by the hatched portion in the figure. .
Only core particles that start coating in a dispersion state of β ≧ 70% can be recovered, and core particles that have not passed through the coating start region and coating particles that have passed through the coating start region are not mixed.
[0070]
From the above, an apparatus for producing coated high-pressure boron nitride particles is composed of a fine particle high dispersion treatment means group and a coating chamber, or a fine particle high dispersion treatment means group, a coating chamber, and a recovery means. However, the constituent elements of these devices can be combined in various ways, and a configuration example of these devices will be described with reference to the drawings as follows.
[0071]
Device configuration 1
FIG. 5A is a block diagram illustrating the configuration of a first apparatus for producing coated high-pressure boron nitride particles. This apparatus of this example includes a coating apparatus manufacturing apparatus main body 2-A, a coating chamber 2-B1, a coating space 2-B2, a coating start area 2-B3, a fine particle highly dispersed treatment means group 2-C1, and a recovery means 2- D. The fine particle highly dispersed treatment means group 2-C1 is directly connected to the coating chamber 2-B1.
[0072]
Device configuration 2
FIG. 5B is a block diagram illustrating the configuration of a second apparatus for producing coated high-pressure boron nitride particles. This apparatus of this example includes a coating apparatus manufacturing apparatus body 2-A, a coating chamber 2-B1, a coating space 2-B2, a coating start area 2-B3, a fine particle high dispersion treatment means group 2-C1, and an inevitable hollow member. 2-C2 and recovery means 2-D. The fine particle highly dispersed treatment means group 2-C1 is connected to the coating chamber 2-B1 through an inevitable hollow member 2-C2.
[0073]
Device configuration 3
FIG. 5 (c) is a block diagram illustrating the configuration of a third apparatus for producing coated high-pressure boron nitride particles. This apparatus of this example includes a coating apparatus manufacturing apparatus main body 2-A, a coating chamber 2-B1, a coating space 2-B2, a coating start area 2-B3, a fine particle high dispersion treatment means group 2-C1, and an air dispersion maintenance. It comprises means 2-C3 and recovery means 2-D. The fine particle high dispersion treatment means group 2-C1 is connected to the coating chamber 2-B1 via the air dispersion maintaining means 2-C3.
[0074]
Device configuration 4
FIG. 5 (d) is a block diagram illustrating the configuration of a fourth apparatus for producing coated high-pressure boron nitride particles. This apparatus of this example includes a coating apparatus manufacturing apparatus main body 2-A, a coating chamber 2-B1, a coating space 2-B2, a coating start area 2-B3, a fine particle highly dispersed treatment means group 2-C1, and a recovery means 2- D. The fine particle highly dispersed treatment means group 2-C1 shares a space with the coating chamber 2-B1.
[0075]
Device configuration 5
FIG. 5 (e) is a block diagram illustrating the configuration of a fifth apparatus for producing coated high-pressure boron nitride particles. This apparatus of this example includes a coating apparatus manufacturing apparatus main body 2-A, a coating chamber 2-B1, a coating space 2-B2, a coating start area 2-B3, a fine particle highly dispersed treatment means group 2-C1, and a recovery means 2- D. The fine particle high dispersion treatment means group 2-C1 is provided in the coating chamber 2-B1.
[0076]
Device configuration 6
FIG. 5 (f) is a block diagram illustrating the configuration of a sixth apparatus for producing coated high-pressure boron nitride particles. This apparatus of this example includes a coating apparatus manufacturing apparatus main body 2-A, a coating chamber 2-B1, a coating space 2-B2, a coating start area 2-B3, a fine particle highly dispersed treatment means group 2-C1, and a recovery means 2- D. A coating chamber 2-B1 is provided in the dispersion space of the fine particle high dispersion treatment means group 2-C1.
[0077]
Device configuration 7
FIG. 5G is a block diagram illustrating the configuration of a seventh apparatus for producing coated high-pressure boron nitride particles. This apparatus of this example includes a coating apparatus manufacturing apparatus main body 2-A, a coating chamber 2-B1, a coating space 2-B2, a coating start area 2-B3, a fine particle highly dispersed treatment means group 2-C1, and a recovery means 2- D, re-coating supply means 2-E. The coated particles after coating from the collecting means 2-D are conveyed to the high dispersion processing means group 2-C1 by the re-coating supply means 2-E, and the coating treatment can be repeated.
The coated high-pressure boron nitride particles are produced by any of the apparatuses having such a configuration.
[0078]
As described above, the coated particles obtained by coating the core particle powder, which is high-pressure boron nitride particles, with the coating forming material may be coated again with the coating forming material, or this recoating may be repeated. In this case, the coated particles are sent to the recoating supply means. Here, the re-coating supply means refers to a means for conveying the coated particles after coating to the fine particle high dispersion treatment means group for re-coating. Specifically, it is a means provided with (a) a collecting means for collecting the coated particles, and (b) a coated particle conveying means for conveying the coated particles from the collecting means to the fine particle high dispersion processing means group. Or (a) recovery means for recovering the coated particles, (b) coated particle transport means for transporting the coated particles from the recovery means to the fine particle high dispersion treatment means group, and (c) and the coated particles for classifying the coated particles after coating. Means provided with classification means. When the coating amount is large, the particle size distribution of the core particle powder before coating and the particle size distribution of the coated particles after coating are changed. Therefore, it is effective to adjust the particle size distribution of the coated particles after coating by the coated particle classification means and perform the recoating treatment.
This re-coating process can be repeated as necessary, and the coating amount of the coating-forming material can be set as desired. Further, the coating process can be repeated by changing the kind of the coating forming material, and thus, a plurality of materials can be multiply coated as the coating forming material.
[0079]
The coated particle manufacturing apparatus used in the present invention is not limited as long as the coating forming material is a coated particle manufacturing apparatus in which the particle surface of the core particle powder is coated by a gas phase method through a gas phase. For example, as a chemical vapor deposition (CVD) apparatus, a thermal CVD apparatus, a plasma CVD apparatus, a CVD (visible light CVD, laser CVD, ultraviolet CVD, infrared CVD, far infrared CVD) apparatus using electromagnetic waves, an MOCVD apparatus, or the like, or As a physical vapor deposition (PVD) apparatus, a vacuum vapor deposition apparatus, an ion sputtering apparatus, an ion plating apparatus, etc. are applicable. More specifically, for example, a coated particle production apparatus described in JP-A-3-75302, particles whose surface is coated with ultrafine particles and a method for producing the same are suitable.
[0080]
As described above, in the present invention, a coating-forming substance precursor that is produced through a gas phase by introducing fine particle core particle powder, which is high-pressure boron nitride, or core particle powder mainly composed of fine particles into the coating space, and Coated high-pressure boron nitride particles that contact and / or collide with the core particle powder particles by coating the surface of the core particle powder particles with the coating material. The basic process of the present invention is summarized as follows.
[0081]
I
(A) The fine particle highly dispersed treatment means group disperses the fine particle core particle powder particles having an average particle diameter of 10 μm or less in the volume reference frequency distribution or the core particle powder particles mainly composed of fine particles in the air. A dispersion process for making a highly dispersed core particle powder / gas mixture,
(B) The core particle powder particles of the highly dispersed core particle powder / gas mixture dispersed in this dispersion step are coated in a dispersion state with a dispersity β of 70% or more in the coating start region of the coating space. A coating process in which coating is initiated by contacting and / or colliding with a forming material precursor;
Coating method.
[0082]
II
(A) Highly dispersed core particles in which particles of a fine particle core particle powder having a volume-based frequency distribution and an average particle diameter of 10 μm or less or core particle powder mainly composed of fine particles are dispersed by a group of fine particle high dispersion treatment means. Powder particles / gas mixture core particle powder particles dispersed in the air by means of a fine particle high dispersion treatment means realizing a particle dispersity β of 70% or more A dispersion process,
(B) The core particle powder particles of the highly dispersed core particle powder / gas mixture dispersed in this dispersion step are coated in a dispersion state with a dispersity β of 70% or more in the coating start region of the coating space. A coating process in which coating is initiated by contacting and / or colliding with a forming material precursor;
Coating method.
[0083]
III
(A) Highly dispersed core particles in which particles of a fine particle core particle powder having a volume-based frequency distribution and an average particle diameter of 10 μm or less or core particle powder mainly composed of fine particles are dispersed by a group of fine particle high dispersion treatment means. Powder particles / gas mixture core particle powder particles dispersed in the air by means of a fine particle high dispersion treatment means realizing a particle dispersity β of 70% or more A dispersion process,
(B) a conveying step of directly conveying the particles of the highly dispersed core particle powder / gas mixture core particle powder dispersed in this dispersing step to the coating step;
(C) Coating of the highly dispersed core particle powder / gas mixture core particle powder transported in this transporting process in a dispersed state with a dispersity β of 70% or more in the coating start region of the coating space A coating process in which the coating is initiated by contacting and / or colliding with a material precursor;
Coating method.
[0084]
IV
(A) Highly dispersed core particles in which particles of a fine particle core particle powder having a volume-based frequency distribution and an average particle diameter of 10 μm or less or core particle powder mainly composed of fine particles are dispersed by a group of fine particle high dispersion treatment means. Powder particles / gas mixture core particle powder particles dispersed in the air by means of a fine particle high dispersion treatment means realizing a particle dispersity β of 70% or more A dispersion process,
(B) A hollow member, an intermediate member made of a member forming a hollow, and a pipe, which are unavoidable for transporting the core particle powder particles of the highly dispersed core particle powder / gas mixture dispersed in the dispersion step A transporting process for transporting through one or more members selected from
(C) Coating of the highly dispersed core particle powder / gas mixture core particle powder transported in this transporting process in a dispersed state with a dispersity β of 70% or more in the coating start region of the coating space A coating process in which the coating is initiated by contacting and / or colliding with a material precursor;
Coating method.
[0085]
V
(A) Highly dispersed core particles in which particles of a fine particle core particle powder having a volume-based frequency distribution and an average particle diameter of 10 μm or less or core particle powder mainly composed of fine particles are dispersed by a group of fine particle high dispersion treatment means. Powder particles / gas mixture core particle powder particles dispersed in the air by means of a fine particle high dispersion treatment means realizing a particle dispersity β of 70% or more A dispersion process,
(B) Highly dispersed core particle powder particles / gas obtained by dispersing the particles of the highly dispersed core particle powder / gas mixture in the dispersion step in the air with the dispersion performance. Air dispersion maintaining means for maintaining the air dispersion state of the particles of the core particle powder of the mixture, the air for enhancing the air dispersion state of the particles of the core particle powder of the highly dispersed core particle powder particles Dispersion facilitating means, separating the particle / gas mixture of the low-dispersion core particle powder in the mixture of the core particle powder particles and gas, and the core particle powder particles are mainly present in the air in a single particle state A conveying step of conveying via one or more of the particle / gas mixture selection means of the highly dispersed core particle powder for selecting the particle / gas mixture of the highly dispersed core particle powder;
(C) Coating of the highly dispersed core particle powder / gas mixture core particle powder transported in this transporting process in a dispersed state with a dispersity β of 70% or more in the coating start region of the coating space A coating process in which the coating is initiated by contacting and / or colliding with a material precursor;
Coating method.
[0086]
As described above, in all of I to V, preferably, a fine particle core particle powder particle having a volume-based frequency distribution and an average particle diameter of 10 μm or less or a core particle powder particle mainly composed of fine particles is subjected to a fine particle high dispersion treatment. Particles of highly dispersed core particle powder in a spatial region in which the dispersity β of the particles of the highly dispersed core particle powder / gas mixture core particle powder dispersed by the means group is 70% or more. A coating start region of the coating space is located in a spatial region including a surface through which all of the particles of the core particle powder in the gas mixture pass, or
A high-dispersion core particle powder in which particles of a fine particle core particle powder having a volume-based frequency distribution and an average particle diameter of 10 μm or less or a core particle powder mainly composed of fine particles are dispersed by a group of fine particle high dispersion treatment means. Covers the spatial region including the surface through which all particles collected by the collecting means of the collecting means pass out of the spatial region in which the particle dispersity β of the core particle powder of the particle / gas mixture is 70% or more. Position the coverage start area of the space, or
Alternatively, in the above I and II, particles of fine particle core particle powder having an average particle diameter of 10 μm or less in a volume-based frequency distribution or particles of core particle powder mainly composed of fine particles are dispersed by a group of fine particle high dispersion treatment means. The high-dispersion core particle powder is dispersed in the air by a group of fine-particle high-dispersion treatment means that realizes a dispersion degree β of the core particle powder of the highly dispersed core particle powder / gas mixture of 70% or more. Part or more of the dispersion step for forming the particle / gas mixture and part or more of the coating step are performed while sharing a part or more of the space.
[0087]
In some cases, the coated high-pressure boron nitride particles form aggregates in contact with each other via a coating-forming substance of the coated particles. The powder composed of the coated high-pressure boron nitride particles includes coated particles in a single particle state, aggregates in which several to several tens of coated particles in a single particle state are in contact, and many more It consists of an agglomerate in which coated particles in a single particle state are in contact, and its shape and size are uneven and irregular. The aggregate composed of the coated particles in a single particle state is preferably crushed and / or crushed before being subjected to molding or sintering. Various crushing means such as a ball mill, a vibrating ball mill, a mortar, a jet mill, etc. can be used for crushing and / or crushing the aggregate of the coated high-pressure boron nitride particles. Further, the coated particles in the single particle state and the aggregate of the coated particles in the single particle state are selectively separated to form or sinter only the coated particles in the single particle state. May be provided.
[0088]
According to the present invention, the coated high-pressure boron nitride powder particles obtained as described above or the mixture containing the particles are sintered under an ultrahigh pressure / high temperature of 2000 MPa or more to obtain a high-pressure boron nitride. This is a sintered body.
In this sintering operation, according to the present invention, it is possible to sinter using only the coated high-pressure boron nitride particles, but this is mixed with uncoated high-pressure boron nitride powder and sintered. It is also possible to sinter by adding a substance exhibiting other functions.
[0089]
When uncoated high-pressure boron nitride powder is mixed, the surface of each coated high-pressure boron nitride particle is already uniformly coated with the coating-forming substance. If an appropriate amount of boron nitride particles is mixed so as to be in contact with each of the uncoated high-pressure boron nitride particles, it is possible to reliably distribute the coating-forming substance to each high-pressure boron nitride particle. Sinterable, uncoated high-pressure boron nitride particles can be added to a relatively large amount of the uncoated high-pressure boron nitride particles as long as the powder particle diameter is relatively large compared to the coated high-pressure boron nitride particles. It is possible to distribute the high-pressure boron nitride particles coated so as to surround the entire high-pressure boron nitride particles with a coating forming material.
[0090]
In addition, in the case of adding a substance that exhibits other functions such as toughness enhancement, this substance is in the form of powder, plate, or particles, and more specifically, the periodic table 1a, 2a, 3a, 4a. 5a, 6a, 7a, 1b, 2b, 3b, 4b, Group 8 metals, semiconductors, semi-metals, rare earth metals and their oxides, nitrides, carbides, oxynitrides, oxycarbides, carbonitrides, acids One or more selected from carbonitrides, borides, silicides, such as Al, B, Si, Fe, Ni, Co, Ti, Nb, V, Zr, Hf, Ta, W, Re, Cr, Cu, Mo, TiAl, Ti_ThreeAl, TiAl_Three, TiNi, NiAl, Ni_ThreeAl, SiC, B_FourC, Cr_ThreeC₂, TiC, ZrC, WC, W₂C, HfC, TaC, Ta₂C, NbC, VC, Mo₂C, Si_ThreeN_Four, TiN, ZrN, Si₂N₂O, w-BN, c-BN, AlN, HfN, V_xN (x = 1 to 3), NbN, TaN, Ta₂N, TiB, TiB₂, ZrB₂, VB, V_ThreeB₂, VB₂, NbB, NbB₂, TaB, TaB₂, MoB, MoB₂, MoB_Four, Mo₂B, WB, W₂B, W₂B_Five, LaB₆, BP, B₁₃P₂, MoSi₂, Al₂O_Three, ZrO₂(Y₂O_Three, Partially stabilized zirconia with added MgO or CaO stabilizer: PSZ, or tetragonal zirconia polycrystal: TZP), MgAl₂O_Four(Spinel), Al₂SiO_FiveIt can be selected from powder and / or particles comprising at least one kind of (mullite).
[0091]
Furthermore, this substance may be a fibrous substance. The fibrous substance mixed with the coated high-pressure boron nitride powder particles is a substance composed of at least one of a metal and a compound having a shape with a minor axis of 500 μm or less and a ratio of the major axis to the minor axis of 2 or more. , A rod-like substance having a minor axis of 500 μm or less and a ratio of the major axis to the minor axis of 2 or more and / or long fibers which are continuous fibers and / or melt-spun into a fiber shape and / or crystals themselves have a fiber shape. It consists of short fibers that are self-shaped fibers and / or whiskers that are crystal-grown in one direction into a fiber shape. In this whisker (whisker crystal), the formation of an intrinsic whisker and / or phase change or chemical change over the whole volume is defined as a phenomenon that does not cause a phase change or a chemical reaction affecting the whole volume. By growing only one crystal face of the crystal to be generated, a broad sense whisker and / or a cross-sectional area indicating a single crystal that has become a long needle crystal is 8 × 10 8.^-Five in²Below, there is a whisker that is a single crystal whose length is 10 times or more of the average diameter.
[0092]
As the fibrous material, periodic table 1a, 2a, 3a, 4a, 5a, 6a, 7a, 1b, 2b, 3b, 4b, 5b, 6b, 7b, group 8 metal, semiconductor, semimetal, rare earth metal, It includes at least one compound containing one or more of non-metals. A fibrous material having a minor axis of 500 μm or less and a ratio of the minor axis to the major axis of 2 or more is used. Specifically, periodic table 1a, 2a, 3a, 4a, 5a, 6a, 7a, 1b, 2b, 3b, 4b, group 8 metal, semiconductor, semimetal, rare earth metal, and carbides and oxides thereof , Nitride, oxycarbide, oxynitride, carbonitride, oxycarbonitride, boride, and silicide, the minor axis is 500 μm or less, and the ratio of the major axis to the minor axis is 2 or more. Some form of fibrous material is used. Preferably, for example, Al, B, Si, Fe, Ni, Co, Ti, Nb, V, Zr, Hf, Ta, W, Re, Cr, Cu, Mo, TiAl, Ti_ThreeAl, TiAl_Three, TiNi, NiAl, Ni_ThreeAl, SiC, B_FourC, Cr_ThreeC₂, TiC, ZrC, WC, W₂C, HfC, TaC, Ta₂C, NbC, VC, Mo₂C, Si_ThreeN_Four, TiN, ZrN, Si₂N₂O, AlN, HfN, V_xN (x = 1 to 3), NbN, TaN, Ta₂N, TiB, TiB₂, ZrB₂, VB, V_ThreeB₂, VB₂, NbB, NbB₂, TaB, TaB₂, MoB, MoB₂, MoB_Four, Mo₂B, WB, W₂B, W₂B_Five, LaB₆, BP, B₁₃P₂, MoSi₂, Al₂O_Three, ZrO₂(Y₂O_Three, Partially stabilized zirconia with added MgO or CaO stabilizer: PSZ, or tetragonal zirconia polycrystal: TZP), MgAl₂O_Four(Spinel), Al₂SiO_FiveA fibrous substance having a minor axis of 500 μm or less and a ratio of the major axis to the minor axis of 2 or more, comprising at least one kind of (mullite), can be selected.
[0093]
Since the coated high-pressure boron nitride particles used in the present invention are coated on the surface by the vapor phase method as described above, the coating forming substance is basically not limited. In order to arbitrarily design the coated high-pressure boron nitride sintered body according to the application, the surface of the high-pressure boron nitride powder particles is preliminarily applied to the surface of the high-pressure boron nitride powder particles before applying the coating. The coating-forming substance may be coated by the same and / or different coating methods.
[0094]
For example, when a coating made of a carbide of the target metal is formed on the surface of high-pressure boron nitride particles, coated high-pressure boron nitride particles coated with carbon in advance may be used. The method for coating the material in advance is not particularly limited. For example, the molten salt immersion method described in JP-A-2-252660, the electroplating method, the electroless plating method, the cladding method, and the physical vapor deposition method are used. A method (sputtering method, ion plating method, etc.) or chemical vapor deposition method is suitable. The metal type of the target metal compound is not particularly limited as long as it can be applied as the binder and / or sintering aid of the present invention.
[0095]
According to the present invention, the coated high-pressure boron nitride particles obtained by coating the surface of the high-pressure boron nitride particles with a coating-forming material by a vapor phase method alone or the coated high-pressure boron nitride particles and the balance being the powder, A mixture obtained by mixing a plate-like substance, particles, etc. and / or the fibrous substance is sintered in a powder form or after molding at an ultrahigh pressure and high temperature of 2000 MPa or more for an appropriate time. The pressure may be any pressure as long as it is 2000 MPa or more, and the temperature is any range in which the high-pressure boron nitride exists in a practically stable manner and the coated high-pressure boron nitride particles to be sintered can be sintered. May be the temperature.
Cubic type, tetra type, girdle type, belt type and the like can be applied to the static ultra high pressure device that generates static ultra high pressure and high temperature of 2000 MPa or more, and there is no particular limitation.
Examples of dynamic devices and methods for generating ultra-high pressure and high temperature of 2000 MPa or more include explosive lenses (planar explosive generators), cylindrical explosion generators, flying object collision methods, magnetic field explosive methods, Mach explosion methods, Known devices and methods such as an overexplosion method, a conical implosion method, a general-type impact gun, and a two-stage light gas gun can be applied, and there is no particular limitation. According to the apparatus and method for generating these dynamic ultra-high pressures and high temperatures, the pressure that can be generated is 10 GPa (10,000 MPa) or more, preferably 40 GPa or more. It can be selected as a suitable example in the case of acting.
[0096]
Depending on the purpose, for example, a pressurizing device and pressure for pressurizing a sample with good reproducibility are used, such as the above-mentioned cubic type ultrahigh pressure device, and various static high pressure devices that generate ultrahigh pressure, and 2000 MPa That's it. The sintering temperature may be slightly deviated from the thermodynamic stability region of the cubic boron nitride.
However, more preferably, sintering is performed under conditions of a thermodynamically stable region of high pressure boron nitride under an ultrahigh pressure and high temperature of 2000 MPa or more.
[0097]
As an example, the production of a high-pressure boron nitride sintered body using a cubic ultra-high pressure apparatus using cubic boron nitride powder as a raw material will be described. First, a coating forming material on the surface of cubic boron nitride powder particles High-pressure boron nitride powder particles coated with, are molded into pellets, surrounded by a hexagonal boron nitride (h-BN) compact, and a graphite tube heater is placed on the outside. To do. Outside the heater, pyrophyllite from which water of crystallization has been removed by heat treatment at 700 ° C. is disposed as a solid pressure medium. The sample thus configured is placed in a cubic ultra-high pressure device, pressurized to a predetermined pressure, then heated to a predetermined temperature, and appropriately sintered for a time. After sintering, the temperature is lowered and the pressure is lowered. A pressure medium is taken out from the cubic type ultra-high pressure device, and a sample is taken out from the pressure medium. In this way, a characteristic, high-pressure boron nitride having a uniform, dense and highly controlled microstructure with a controlled distribution of binder and / or sintering aid and / or surface modifier A high-performance coated high-pressure boron nitride sintered body composed of
[0098]
【Example】
Hereinafter, the coated high-pressure boron nitride sintered body of the present invention and the manufacturing method thereof will be described in more detail with reference to examples.
Example 1
As high-pressure boron nitride powder particles, average particle diameter D_MIs 1 μm and the volume-based frequency distribution is ([D_M/ 2,3D_M/ 2], ≧ 90%) cubic boron nitride particles were coated with zirconium metal.
The apparatus used is shown in FIG. 6 and FIG. 7 which is a partially enlarged view thereof, and is a specific example of the configuration shown in FIG.
The apparatus of this example includes a plasma torch 3-A, a plasma chamber 3-a, a coating forming material precursor generating chamber cooling bath 3-B, a coating forming material precursor generating chamber 3-b, and a coating chamber cooling bath 3 in a narrow sense. -C, coating chamber 3-c in a narrow sense, coating particle cooling chamber cooling tank 3-D, coating particle cooling chamber 3-d, supply device 3-E1, core particle powder on the material supply side of the coating forming substance Are provided with a stirring type dispersing device 3-F1, an ejector type dispersing device 3-H1, a thin tube dispersing device 107, and a coated particle collecting unit 3-G. The supply device 3-E1 is connected to a supply device 112 provided with a raw material powder supply tank of the coating forming substance, and the stirring type dispersing device 3-F1 is connected to a supply device 111 provided with a core particle powder supply tank. . The coating chamber in this example is composed of a plasma chamber 3-a, a coating forming material precursor generation chamber 3-b, a narrowly defined coating chamber 3-c, and a coated particle cooling chamber 3-d. Is referred to as a covering chamber in a broad sense. Of the covering chamber in a broad sense, the chamber 3-c in which coating processing is mainly performed is referred to as a narrowly covering chamber.
[0099]
The fine particle high dispersion treatment means group α in this example is constituted by a feeder 111 having a feeding tank, an agitating type dispersing device 3-F1 and an ejector type dispersing device 3-H1, and a stainless steel thin tube dispersing device 107 having an inner diameter of 4 mm. FIG. 2 (a) shows a specific example of the fine particle high dispersion processing means group belonging to the configuration shown in FIG. 3 (b). The fine particle high dispersion treatment means group is D_M= 1 μm ([D_M/ 5,5D_M] ≧≧ 90%) high-pressure boron nitride core particle powder particles are configured to realize β ≧ 70% at the time of output. The narrow tube 107 which is the final processing means of the fine particle high dispersion processing means group is directly connected to the coating chamber 3-C, and is configured such that β ≧ 70% can be realized in the coating start area 3-L1 of the coating space 3-L2. Has been.
[0100]
Argon gas is supplied at a rate of 20 liters / minute from a supply source 102 to a gas outlet 101 provided on the top of the plasma torch 3-A. This argon gas is turned into plasma by the applied high frequency and forms a plasma soot in the plasma chamber 3-a in the plasma torch 3-A.
Zirconium metal powder having an average particle diameter of 12 μm, which is a raw material of the coating forming material supplied from a feeder 112 equipped with a raw material supply tank of the coating forming material, is carried on a carrier gas 103 of 5 liters / minute, and a plasma torch 3-A is introduced into the plasma soot at a rate of 0.6 g / min from the coating material feed inlet 104 provided in the lower part of the coating material, evaporates by the heat of the plasma soot, passes through the gas phase, and forms the coating. It becomes a coating forming material precursor in the material precursor generation chamber 3-b.
Cubic boron nitride core particles having an average particle diameter of 1 μm supplied at 1.2 g / min from a supply device 111 equipped with a core particle powder supply tank are dispersed by a stirring disperser 3-F1 and 5 liters. Is dispersed by a carrier gas 105 supplied at a rate of / min. And dispersed in a dispersion state with a dispersity β = 82% by an ejector-type disperser 3-H1 and a thin tube disperser 107 with a dispersion gas 106 having a flow rate of 10 liters / min. And introduced into the coating chamber.
Highly dispersed cubic boron nitride particles begin to contact and / or collide with the coating-forming material precursor in a dispersed state of β = 82% in the 3-L2 coating initiation region 3-L1 of the coating space.
[0101]
The coated cubic boron nitride particles whose surface is coated with the coating-forming substance thus generated descends in the coated particle cooling chamber 3-d together with the gas, and reaches the coated particle recovery unit 3-G. . The product made of the coated particles is separated from the gas by the filter 110 and collected and taken out.
In this way, coated cubic boron nitride particles were obtained in which the zirconium boron particles were coated with 20% by volume of zirconium metal.
[0102]
The obtained cubic boron nitride particles, which are cubic boron nitride fine particles whose surface was coated with zirconium metal, were observed with a scanning electron microscope. As shown in FIG. Also, zirconium metal of about 0.005 μm was uniformly coated in ultrafine particles.
The coated cubic boron nitride particle powder coated with 20% by volume of zirconium metal is embossed to an outer diameter of 6 mm and a height of 2 mm, and a hexagonal boron nitride (h-BN) compact is formed on the outside. Embedded in a pressure medium arranged at 200 ° C., 10^-3 Low boiling impurities were removed by vacuum drying with torr all day and night. This was set in a cubic type ultrahigh pressure apparatus, first the pressure was increased to 5.5 GPa at room temperature, the temperature was raised to 1450 ° C., the temperature was lowered after holding for 30 minutes, and the pressure was lowered.
[0103]
When the obtained sintered body was examined by X-ray diffraction, zirconium and cubic boron nitride reacted and zirconium metal disappeared, and cubic boron nitride, ZrN, and ZrB₂Changed. This sintered body was found to be cubic boron nitride, ZrN and ZrB according to quantitative X-ray analysis.₂Were about 77%, 14% and 9%, respectively.
The surface of the obtained sintered body was polished with diamond paste, and the Vickers microhardness (Hv) was measured. FIG. 9 shows Hv (0.5 / 10) of the cubic boron nitride sintered body of Example 1. For comparison, a cubic boron nitride sintered body using a ceramic-based binder or sintering aid is shown. The hardness of four typical commercially available cutting tools is also shown. The sintered body obtained in Example 1 had a very high Hv (0.5 / 10) of about 5500. This value was equal to or higher than that of a commercially available cubic boron nitride sintered body cutting tool. Moreover, the hardness of the sintered body of Example 1 was constant over the entire hardness measurement surface of the sintered body, and there was almost no variation.
[0104]
FIG. 10 shows an electron micrograph (× 5000) of the polished surface obtained by subjecting the polished surface of the sintered body of Example 1 to normal gold vapor deposition for observation. In the figure, the dark part is cubic boron nitride, and the bright part is ZrN-ZrB.₂It is a system substance. As is apparent from FIG. 10, there were no pores in the sintered body, and the sintered body could be sintered to a relative density of 100%. Moreover, there were no unsintered parts. Where the coating-forming material is thin and the cubic boron nitride particles are in contact, the cubic boron nitride particles break through the coating and sinter and bond directly. Other than this, ZrN-ZrB₂It can be seen that the systemic material is a characteristic sintered body that is distributed around cubic boron nitride particles and has a dense, uniform, highly distributed microstructure binder. In addition, the cubic boron nitride particles have no grain growth compared to the raw material cubic boron nitride powder, and the cubic boron nitride and the zirconium metal which is a coating forming substance chemically react to form a coating. The cubic boron nitride particles in the compact are also characterized by being finer than the raw material before coating. This is very favorable for the mechanical properties of the sintered body and is ideal. Electron micrographs (x5000) of a polished surface obtained by subjecting the polished surface of the commercially available representative cubic boron nitride sintered body cutting tool shown in FIG. 11 to normal gold vapor deposition for observation are shown in FIG. ) Clearly shows the difference. That is, in commercially available cubic boron nitride sintered body cutting tools, the distribution of binders and sintering aids is irregular, and the binders and sintering aids are in a lump. On the other hand, there are not a few deficiencies in sintering aids and binders, and there are unsintered parts. Furthermore, the fact that the cubic boron nitride particles of this cutting tool are all coarse is a significant difference from the first embodiment.
As described above, although cubic boron nitride is inherently very difficult to sinter, the coated cubic boron nitride powder particles of the present invention are comparable to those at industrial high temperatures and temperatures. It behaves like particles that are easily sintered and forms a dense, strong, and high hardness structure.
[0105]
Example 2
Average particle diameter D_MIs 1 μm and the volume-based frequency distribution is ([D_M/ 2,3D_M/ 2], ≧ 90%) cubic boron nitride particles were coated with titanium metal.
The apparatus used is shown in FIG. 12 and FIG. 13 which is a partially enlarged view thereof, and is a specific example of the configuration shown in FIG. The configuration of the apparatus for producing the coating forming material precursor of this example is the same as that of Example 1. The fine particle high dispersion treatment means group α is composed of a feeder 214 equipped with a feeding tank, a stirring type dispersing machine 5-F1, a thin tube dispersing machine 211, and a dispersing machine 5-H2 using a collision plate. It is shown in a) and is a specific example of a group of fine particle high dispersion processing means belonging to the configuration shown in FIG. The thin tube disperser 211 is made of stainless steel having an inner diameter of 4 mm. The disperser 5-H2 using the collision plate which is the final dispersion means of the fine particle high dispersion processing means group α has a configuration in which a collision plate 213 made of SiC is installed by a stainless steel holder 212. The disperser 5-H2 using the collision plate is provided in the narrowly defined coating chamber 5-c, and the fine particle high dispersion processing means group α and the narrowly defined coating chamber 5-c have a common space. . Further, the coating space 5-L1 and the coating start area 5-L2 of the coating space are provided in a narrowly defined coating chamber 5-c. The fine particle highly dispersed treatment means group of this apparatus has an average particle diameter D_MIs 1 μm and the volume-based frequency distribution is ([D_M/ 5,5D_M, ≧ 90%) of the core particle powder can be dispersed to a dispersion degree β ≧ 70% immediately after the collision of the collision plate 213 of the disperser 5-H2 using the collision plate as the final dispersion treatment. Therefore, coating is started with a dispersion degree β ≧ 70%.
[0106]
Argon gas of 20 liters / min is supplied from a supply source 202 to a gas outlet 201 provided on the upper part of the plasma torch 5-A. This argon gas is turned into plasma by the applied high frequency and forms a plasma soot in the plasma chamber 5-a in the plasma torch 5-A.
The titanium metal powder having an average particle diameter of 25 μm, which is the raw material of the coating forming material supplied from the feeder 215 equipped with the raw material supply tank of the coating forming material at 0.4 g / min, is transferred to the carrier gas 203 of 5 liter / min. A coating forming material precursor is introduced into the plasma soot from the coating material feed inlet 204 provided under the plasma torch 5-A, evaporates by the heat of the plasma soot and passes through the gas phase, It becomes a coating-forming substance precursor in the body generation chamber 5-b.
The cubic boron nitride core particles supplied at a rate of 1.2 g / min from a feeder 214 equipped with a core particle powder supply tank are dispersed by a stirring disperser 5-F1 at a rate of 20 liters / min. It is carried by the supplied carrier gas 205, passes through the thin tube disperser 211, and is dispersed in the air at a dispersity β = 82% by a disperser 5-H2 using a collision plate provided in the coating chamber.
Highly dispersed cubic boron nitride core particles begin to contact and / or collide with the coating-forming material precursor in a dispersed state of β = 82% in the coating initiation region 5-L1 of the coating space 5-L2.
[0107]
The coated cubic boron nitride particles whose surface is coated with the coating forming material thus generated descends with the gas in the coated particle cooling chamber 5-d and reaches the coated particle recovery unit 5-G. . The product composed of the coated cubic boron nitride particles is separated from the gas by the filter 210 and collected and taken out.
The obtained cubic boron nitride particles, which are cubic boron nitride fine particles whose surface is coated with titanium metal, were observed with a scanning electron microscope. The titanium metal of about 0.005 μm was coated in ultrafine particles. The coating amount of titanium metal was 20% by volume.
[0108]
Cubic boron nitride particle powder coated with 20% by volume of titanium metal thus obtained was embossed to an outer diameter of 6 mm and a height of 2 mm. First, the pressure was increased to 5.3 GPa at room temperature, the temperature was raised to 1480 ° C., the temperature was lowered after holding for 30 minutes, and the pressure was lowered. The obtained sintered body had no pores, could be densified to a relative density of 100%, and had no unsintered portion. The surface of this sintered body was polished with diamond paste and measured for Vickers microhardness. As a result, Hv (0.5 / 10) was as high as about 5600. When the crystal phase of this sintered body was examined by powder X-ray diffraction, cubic boron nitride, TiN and TiB₂Was only recognized. According to X-ray quantitative analysis, the sintered body is cubic boron nitride, TiN and TiB.₂Were about 74%, 15% and 11%, respectively.
As in Example 1, also in Example 2, the sintered body had a dense, uniform and almost uniform distribution of the binder and a highly controlled microstructure.
[0109]
Example 3
The average particle size is 1 μm and the volume-based frequency distribution is ([D_M/ 2,3D_M/ 2], ≧ 90%) was coated with titanium nitride which is a titanium metal nitride.
The apparatus used is shown in FIG. 14 and FIG. 15 which is a partially enlarged view thereof, and is a specific example of the configuration shown in FIG. The configuration of the apparatus for producing the coating forming material precursor of this example is the same as that of Example 1. The fine particle high dispersion treatment means group α includes a supply device 313 provided with a supply tank, a stirring disperser 6-F1 which is a dispersion means, and a cyclone 6-I which is a particle / gas mixture selection means for highly dispersed core particle powder. FIG. 2 (b) shows a specific example of the fine particle high dispersion processing means group having the configuration shown in FIG. 3 (d). The discharge part of the particle / gas mixture of the highly dispersed core particle powder of the cyclone 6-I is connected to the coating chamber 6-c in a narrow sense by a pipe 307 unavoidable for conveyance, and the discharge part of the low dispersion core particle powder part is discharged. The section is connected to the agitating disperser 6-F1 by a transport pipe 310 through a hopper 6-J and a rotary valve 6-K. According to the fine particle high dispersion processing means group of the present apparatus, the average particle diameter D as a volume-based particle size distribution._MIs 1 μm and the volume-based frequency distribution is ([D_M/ 5,5D_M, ≧ 90%) of the core particle powder can be dispersed at a dispersion degree β ≧ 75% at the discharge part of the highly dispersed core particle powder flow of cyclone 6-I as the final processing means. As shown in FIGS. 14 and 15, a coating space 6-c in a narrow sense is provided with a coating space 6-L2 and a coating start area 6-L1 of the coating space. The decrease in the dispersity β due to the pipe 307 unavoidable for conveyance due to the restriction of the flange portion connecting 6-C and 6-D can be kept small. Therefore, in the coating start region, coating is started with a dispersion degree β ≧ 70%.
[0110]
Argon gas is supplied from a supply source 302 at a rate of 20 liters / minute to a gas outlet 301 provided on the top of the plasma torch 6-A. The argon gas is turned into plasma by the applied high frequency and forms a plasma soot in the plasma chamber 6-a in the plasma torch 6-A.
The titanium nitride powder, which is the raw material of the coating forming material supplied at 0.6 g / min from the supply device 314 equipped with the raw material supply tank of the coating forming material, is supported on the carrier gas 303 at 5 liter / min, 6-A is introduced into the plasma soot from the coating material feed inlet 304 provided at the bottom of the 6A, evaporates by the heat of the plasma soot and passes through the gas phase, and then the coating-forming material precursor generation chamber 6-b. It becomes a coating-forming substance precursor.
Cubic boron nitride core particles supplied at 2.0 g / min from a supply machine 313 equipped with a core particle powder supply tank are dispersed by a stirring disperser 6-F1, and a carrier gas of 15 liters / min. It is carried by 305 and conveyed to the cyclone 6 -I through the pipe 306. Cyclone 6-I is adjusted so that the maximum particle size on the fine powder side is 1.5 μm, and particles / gas of highly dispersed core particle powder in a dispersed state of β = 85% mainly composed of single particles. The mixture is discharged from the discharge port 308 through the pipe 307 that is inevitable for conveyance into the narrowly defined coating chamber 6-c. On the other hand, the low dispersion core particle powder portion selectively separated by the cyclone 6-I is conveyed through the pipe 310 by the carrier gas 309 through the hopper 6-J and the rotary valve 6-K, and is stirred. Feedback to the disperser 6-F1.
[0111]
The highly dispersed cubic boron nitride core particles begin to contact and / or collide with the coating forming material precursor in a dispersion state of β = 82% in the coating start region 6-L1 of the coating space 6-L2.
The coated cubic boron nitride particles whose surface is coated with the coating forming material thus generated descends with the gas in the coated particle cooling chamber 6-d and reaches the coated particle recovery unit 6-G. . The product composed of the coated cubic boron nitride particles is separated from the gas by the filter 312 and collected and taken out.
[0112]
The obtained coated particles, which were cubic boron nitride fine particles whose surface was coated with titanium nitride, were observed with a scanning electron microscope. As a result, each of the particles was uniformly made of titanium nitride of about 0.005 μm. It was coated in ultrafine particles. The coating amount of titanium nitride was 15% by volume.
Cubic boron nitride powder coated with 15% by volume of titanium nitride thus obtained was embossed to an outer diameter of 6 mm and a height of 2 mm. First, the pressure was increased to 5.3 GPa at room temperature, then the temperature was raised to 1480 ° C., the temperature was lowered after holding for 30 minutes, and the pressure was lowered. The obtained sintered body had no pores, could be densified to a relative density of 100%, and had no unsintered portion. The surface of this sintered body was polished with diamond paste and measured for Vickers microhardness. As a result, Hv (0.5 / 10) was as high as about 6400. When the crystal phase of the sintered body was examined by powder X-ray diffraction, only cubic boron nitride and TiN were observed. In Example 3 as well, the sintered body had a highly controlled microstructure with a dense, uniform and substantially network-like binder distribution.
[0113]
Example 4
Using the apparatus of Example 3, coating was performed under substantially the same conditions as in Example 3 to obtain coated cubic boron nitride particle powder coated with 20% by volume of titanium nitride. This coated cubic boron nitride particle powder was stamped and molded to an outer diameter of 6 mm and a height of 2 mm, and set in a cubic type ultrahigh pressure apparatus as in Example 3, and first, the pressure was increased to 5.3 GPa at room temperature. Thereafter, the temperature was raised to 1480 ° C., held for 30 minutes, the temperature was lowered, and the pressure was lowered. The obtained sintered body had no pores, could be densified to a relative density of 100%, and had no unsintered portion. The surface of this sintered body was polished with diamond paste and measured for Vickers microhardness. As a result, Hv (0.5 / 10) was as high as about 5900. When the crystal phase of this sintered body was examined by powder X-ray diffraction, only cubic boron nitride and TiN were found, as in Example 3. In Example 4 as well, the sintered body had a highly controlled microstructure with a dense and uniform binder distribution.
[0114]
Example 5
Using the apparatus of Example 1, coating was performed under substantially the same conditions as in Example 1 to obtain a coated cubic boron nitride particle powder coated with 20% by volume of aluminum nitride. This coated cubic boron nitride particle powder was stamped and molded to an outer diameter of 6 mm and a height of 2 mm, and set in a cubic type ultrahigh pressure apparatus as in Example 1 and first pressurized to 5.4 GPa at room temperature. Then, the temperature was raised to 1450 ° C., held for 30 minutes, the temperature was lowered, and the pressure was lowered. The obtained sintered body had no pores, could be densified to a relative density of 100%, and had no unsintered portion. The surface of this sintered body was polished with diamond paste and measured for Vickers microhardness. As a result, Hv (0.5 / 10) was as high as about 5800. When the crystal phase of the sintered body was examined by powder X-ray diffraction, cubic boron nitride and AlN were only found. In Example 5 as well, the sintered body had a highly controlled microstructure with a dense and uniform binder distribution.
[0115]
Example 6
Using the apparatus of Example 1, coating was performed under substantially the same conditions as in Example 5 to obtain coated cubic boron nitride particle powder coated with 30% by volume of aluminum nitride. This coated cubic boron nitride particle powder was embossed to an outer diameter of 6 mm and a height of 2 mm, and set in a cubic type ultrahigh pressure apparatus, as in Example 5, and first pressurized to 5.4 GPa at room temperature. Then, the temperature was raised to 1450 ° C., held for 30 minutes, the temperature was lowered, and the pressure was lowered. The obtained sintered body had no pores, could be densified to a relative density of 100%, and had no unsintered portion. The surface of this sintered body was polished with diamond paste and measured for Vickers microhardness. As a result, Hv (0.5 / 10) was as high as about 5200. When the crystal phase of the sintered body was examined by powder X-ray diffraction, only cubic boron nitride and AlN were found as in Example 5. In Example 6 as well, the sintered body had a dense and uniform binder distribution with a highly controlled microstructure.
[0116]
Example 7
Using the apparatus of Example 1, coating was performed under substantially the same conditions as in Example 1 to obtain coated cubic boron nitride particle powder coated with 20% by volume of silicon nitride. The coated cubic boron nitride particle powder was stamped and molded to an outer diameter of 6 mm and a height of 2 mm, and set in a cubic type ultrahigh pressure apparatus, as in Example 1, and first pressurized to 5.3 GPa at room temperature. Thereafter, the temperature was raised to 1470 ° C., held for 30 minutes, the temperature was lowered, and the pressure was lowered. The obtained sintered body had no pores, could be densified to a relative density of 100%, and had no unsintered portion. The surface of this sintered body was polished with diamond paste and measured for Vickers microhardness. As a result, Hv (0.5 / 10) was as high as about 5900. When the crystal phase of this sintered body was examined by powder X-ray diffraction, cubic boron nitride, α-Si_ThreeN_Four, Β-Si_ThreeN_FourWas only recognized. In Example 7 as well, the sintered body had a highly controlled microstructure with a dense and uniform binder distribution.
[0117]
Example 8
Using the apparatus of Example 1, coating was performed under substantially the same conditions as in Example 7 to obtain coated cubic boron nitride particle powder coated with 30% by volume of silicon nitride. This coated cubic boron nitride particle powder was stamped and molded to an outer diameter of 6 mm and a height of 2 mm, and set in a cubic type ultrahigh pressure apparatus as in Example 7, and first, the pressure was increased to 5.3 GPa at room temperature. Thereafter, the temperature was raised to 1470 ° C., held for 30 minutes, the temperature was lowered, and the pressure was lowered. The obtained sintered body had no pores, could be densified to a relative density of 100%, and had no unsintered portion. The surface of this sintered body was polished with diamond paste, and the Vickers microhardness was measured. As a result, Hv (0.5 / 10) was as high as about 5100. The crystal phase of the sintered body was examined by powder X-ray diffraction. As in Example 7, cubic boron nitride, α-Si_ThreeN_Four, Β-Si_ThreeN_FourWas only recognized. In Example 8 as well, the sintered body had a highly controlled microstructure with a dense and uniform binder distribution.
[0118]
Example 9
The coating of Example 2 was performed under substantially the same conditions as in Example 2 to obtain coated cubic boron nitride particle powder coated with 15% by volume of aluminum oxide. This coated cubic boron nitride particle powder was stamped and molded to an outer diameter of 6 mm and a height of 2 mm, and set in a cubic type ultrahigh pressure apparatus as in Example 2, and first, the pressure was increased to 5.5 GPa at room temperature. Then, the temperature was raised to 1450 ° C., held for 30 minutes, the temperature was lowered, and the pressure was lowered. The obtained sintered body had no pores, could be densified to a relative density of 100%, and had no unsintered portion. The surface of this sintered body was polished with diamond paste and measured for Vickers microhardness. As a result, Hv (0.5 / 10) was as high as about 6100. When the crystal phase of this sintered body was examined by powder X-ray diffraction, cubic boron nitride, α-Al₂O_ThreeWas only recognized. Also in Example 9, the sintered body had a dense and uniform distribution of binder and a highly controlled microstructure.
[0119]
Example 10
Coating was performed using the apparatus of Example 2 under substantially the same conditions as in Example 9 to obtain coated cubic boron nitride particle powder coated with 20% by volume of aluminum oxide. This coated cubic boron nitride particle powder was stamped and molded to an outer diameter of 6 mm and a height of 2 mm, and set in a cubic type ultrahigh pressure apparatus, as in Example 9, and first pressurized to 5.6 GPa at room temperature. Then, the temperature was raised to 1450 ° C., held for 30 minutes, the temperature was lowered, and the pressure was lowered. The obtained sintered body had no pores, could be densified to a relative density of 100%, and had no unsintered portion. The surface of this sintered body was polished with diamond paste and measured for Vickers microhardness. As a result, Hv (0.5 / 10) was as high as about 5900. The crystal phase of the sintered body was examined by powder X-ray diffraction. As in Example 9, cubic boron nitride, α-Al₂O_ThreeWas only recognized. In Example 10 as well, the sintered body had a highly controlled microstructure with a dense and uniform binder distribution.
[0120]
Example 11
Using the apparatus of Example 1, coating was performed under substantially the same conditions as in Example 1 to obtain coated cubic boron nitride particle powder coated with 10% by volume of cobalt metal. This coated cubic boron nitride particle powder was stamped and molded to an outer diameter of 6 mm and a height of 2 mm, and set in a cubic type ultrahigh pressure apparatus as in Example 1 and first pressurized to 5.5 GPa at room temperature. Then, the temperature was raised to 1450 ° C., held for 30 minutes, the temperature was lowered, and the pressure was lowered. The obtained sintered body had no pores, could be densified to a relative density of 100%, and had no unsintered portion. Further, there was no cobalt metal pool in the sintered body. The surface of this sintered body was polished with diamond paste and measured for Vickers microhardness. As a result, Hv (0.5 / 10) was about 6000, which was high. When the crystal phase of the sintered body was examined by powder X-ray diffraction, only cubic boron nitride and cobalt were found. In Example 11 as well, the sintered body had a fine and highly controlled microstructure with a uniform and uniform binder distribution.
[0121]
Example 12
Coating was performed using the apparatus of Example 1 under substantially the same conditions as in Example 11 to obtain coated cubic boron nitride particle powder coated with 30% by volume of cobalt metal. This coated cubic boron nitride particle powder was press-molded to an outer diameter of 6 mm and a height of 2 mm, and set in a cubic type ultrahigh pressure apparatus, as in Example 11, and first pressurized to 5.5 GPa at room temperature. Then, the temperature was raised to 1450 ° C., held for 30 minutes, the temperature was lowered, and the pressure was lowered. The surface of the obtained sintered body was polished with diamond paste, and the Vickers microhardness was measured. As a result, Hv (0.5 / 10) was as high as about 2800. The density was 100%. When the crystal phase of this sintered body was examined by powder X-ray diffraction, as in Example 11, cubic boron nitride and cobalt were only observed. In Example 12 as well, the sintered body was dense and had a uniform binder distribution.
[0122]
Example 13
Using the apparatus of Example 1, coating was performed by the RF plasma method under substantially the same conditions as in Example 1. First, nickel metal and then aluminum metal at a molar ratio of 3: 1₃A coated cubic boron nitride powder coated with 15% by volume in terms of Al was obtained. The coated cubic boron nitride powder was stamped and molded to an outer diameter of 6 mm and a height of 2 mm, and set in a cubic type ultrahigh pressure apparatus, as in Example 1, first pressurized to 5.1 GPa at room temperature, and then 1450 The temperature was raised to 0 ° C., held for 30 minutes, then lowered, and the pressure was lowered. The obtained sintered body had no pores, could be densified to a relative density of 100%, and had no unsintered portion. The surface of this sintered body was polished with diamond paste and measured for Vickers microhardness. As a result, Hv (0.5 / 10) was as high as about 4300. When the crystal phase of this sintered body was examined by powder X-ray diffraction, cubic boron nitride, Ni₃Only Al was observed. In Example 13 as well, the sintered body had a highly controlled microstructure with a dense and uniform binder distribution.
[0123]
Example 14
Using the apparatus of Example 1, coating was performed under substantially the same conditions as in Example 13. First, nickel metal was coated, and then aluminum metal was coated at a molar ratio of 1: 1 at a NiAl equivalent volume of 20%. Cubic boron nitride particle powder was obtained. This coated cubic boron nitride particle powder was stamped and molded to an outer diameter of 6 mm and a height of 2 mm, and set in a cubic type ultrahigh pressure apparatus as in Example 13, and first the pressure was increased to 5.1 GPa at room temperature. Then, the temperature was raised to 1450 ° C., held for 30 minutes, the temperature was lowered, and the pressure was lowered. The obtained sintered body had no pores, could be densified to a relative density of 100%, and had no unsintered portion. The surface of this sintered body was polished with diamond paste and measured for Vickers microhardness. As a result, Hv (0.5 / 10) was as high as about 3300. When the crystal phase of the sintered body was examined by powder X-ray diffraction, cubic boron nitride and NiAl were found. In Example 14 as well, the sintered body had a dense and uniform distribution of binder and a highly controlled microstructure.
[0124]
Example 15
90% by volume of the coated cubic boron nitride particle powder obtained by applying a titanium nitride coating of 20% by volume obtained in Example 4 and the balance being silicon carbide whiskers (SiC: minor axis 0.5 μm, average) 30% in length) was mixed in a volume of 10% by wet in acetone and then vacuum dried to obtain a mixture. This mixture was stamped and molded to an outer diameter of 6 mm and a height of 2 mm, and set in a cubic type ultrahigh pressure apparatus as in Example 4. First, the pressure was raised to 5.5 GPa at room temperature, and then the temperature was raised to 1500 ° C. After holding for 30 minutes, the temperature was lowered and the pressure was lowered. The obtained sintered body had no pores, could be densified to a relative density of 100%, and had no unsintered portion. The surface of this sintered body was polished with diamond paste and the Vickers microhardness was measured. As a result, Hv (0.5 / 10) was about 5000 and high hardness. The crystal phase of this sintered body was examined by powder X-ray diffraction. As a result, only cubic boron nitride and TiN were found in the same manner as in Example 4 except for SiC. Also in this Example 15, the sintered body is a dense and uniform composite sintered body having a highly controlled microstructure in which the titanium nitride binder and SiC whiskers are uniformly dispersed among the cubic boron nitride particles. It was.
[0125]
Example 16
Using the apparatus of Example 1, coating was performed under substantially the same conditions as in Example 7, and 90% by volume of the coated cubic boron nitride particle powder coated with 20% by volume of silicon nitride and the balance being Silicon carbide whiskers (SiC: minor axis 0.5 μm, average length 30 μm) were mixed in a volume of 10% by wet in acetone and then vacuum dried to obtain a mixture. This mixture was stamped to an outer diameter of 6 mm and a height of 2 mm, and set in a cubic type ultrahigh pressure apparatus as in Example 7. First, the pressure was raised to 5.3 GPa at room temperature, and then the temperature was raised to 1470 ° C. After holding for 30 minutes, the temperature was lowered and the pressure was lowered. The obtained sintered body had no pores, could be densified to a relative density of 100%, and had no unsintered portion. The surface of this sintered body was polished with diamond paste, and the Vickers microhardness was measured. As a result, Hv (0.5 / 10) was as high as about 5100. When the crystal phase of this sintered body was examined by powder X-ray diffraction, except for SiC, cubic boron nitride, α-Si was used in the same manner as in Example 7._ThreeN_Four, Β-Si_ThreeN_FourWas only recognized. Also in this Example 16, the sintered body is a dense and uniform composite sintered body having a highly controlled microstructure in which silicon nitride binder and SiC whiskers are uniformly dispersed among cubic boron nitride particles. Obtained.
[0126]
【The invention's effect】
According to the present invention, a core particle powder composed of fine particles of high-pressure boron nitride having a volume-based frequency distribution and an average particle diameter of 10 μm or less is dispersed in the air, and the particles of the dispersed core particle powder are dispersed in β The coated high-pressure boron nitride particles or the same particles coated with the coating-forming material on the surface in a single particle state by contacting or colliding with the coating-forming material precursor in a dispersed state in which is 70% or more. High-performance coated high-pressure mold with a highly controlled microstructure that is uniformly, densely and strongly sintered by sintering a mixture containing it at an ultrahigh pressure and temperature of 2000 MPa or more A boron nitride sintered body was obtained.
[Brief description of the drawings]
FIG. 1 is a distribution diagram of powder particles, where (a) represents the dispersity β, and (b) represents the particle size D.₁~ D₂The particle size of the powder in which the range of particles occupies 90% by volume versus the volume-based frequency is expressed.
FIGS. 2A to 2C are block diagrams showing the basic configuration of a fine particle high dispersion processing means group.
FIGS. 3A to 3G are block diagrams for explaining the configuration of a fine particle high dispersion processing means group in more detail.
FIGS. 4A to 4E are views showing a state in which coating of core particle powder is started.
FIGS. 5A to 5G are block diagrams illustrating the configuration of an apparatus for producing coated high-pressure boron nitride particles.
6 is a diagram showing an apparatus used in Example 1. FIG.
7 is a partially enlarged view of the apparatus used in Example 1. FIG.
8 is a scanning electron micrograph of the coated cubic boron nitride particles obtained in Example 1. FIG.
FIG. 9 is a view showing Vickers microhardness of a cubic boron nitride sintered body.
10 is an electron micrograph of the polished surface of the sintered body of Example 1. FIG.
FIG. 11 is an electron micrograph of a polished surface of a commercially available cubic boron nitride sintered body tool.
12 shows an apparatus used in Example 2. FIG.
13 is a partially enlarged view of the apparatus used in Example 2. FIG.
14 shows an apparatus used in Example 3. FIG.
15 is a partially enlarged view of the apparatus used in Example 3. FIG.

Claims (9)

高圧型窒化硼素の微粒子からなる、芯粒子粉体の粒子又は主に同微粒子からなる芯粒子粉体の粒子であってその表面が被覆形成物質で被覆されたものを焼結して、高圧型窒化硼素焼結体を製造する方法において、
この被覆形成物質で被覆された高圧型窒化硼素粒子は、芯粒子粉体を被覆空間に投入し、気相を経て生成する被覆形成物質前駆体及び／又は気相状態の被覆形成物質前駆体を、この芯粒子粉体の粒子に接触及び／又は衝突させて、芯粒子粉体の粒子の表面が被覆形成物質で被覆され、
（Ａ）分散手段として、この芯粒子粉体の粒子を気中に分散させる、撹拌式分散機、エジェクター式分散機、細管分散機よりなる分散手段を有する微粒子高分散処理手段群により、体積基準頻度分布で平均粒子径が１０μｍ以下の微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子を、気中に分散させて高分散芯粒子粉体の粒子・気体混合物とする分散工程、
（Ｂ）この分散工程で分散させた芯粒子粉体の粒子を、被覆空間の被覆開始領域に、全粒子の重量に対する見かけの一次粒子状態の粒子の重量の割合である分散度βが７０％以上の分散状態で、被覆工程に直接放出し、被覆形成物質前駆体と接触及び／又は衝突させる被覆工程、並びに
（Ｃ）この被覆工程によって得た被覆高圧型窒化硼素粒子、又は同粒子を含む混合物を２０００MPa以上の圧力、及び高温度において焼結する工程
を備えることを特徴とする被覆高圧型窒化硼素焼結体の製造法。High-pressure-type boron nitride particles consisting of core powder particles or core-particle powder particles mainly consisting of the same fine particles, the surface of which is coated with a coating-forming substance, are sintered to form a high-pressure type In the method for producing a boron nitride sintered body,
The high-pressure boron nitride particles coated with this coating forming material are prepared by introducing a core forming powder into a coating space and forming a coating forming material precursor and / or a coating forming material precursor in a gas phase state through a gas phase. The surface of the core particle powder particles is coated with a coating-forming substance by contacting and / or colliding with the core particle powder particles,
(A) As a dispersion means, a volume-based high-dispersion treatment means group having a dispersion means comprising a stirring-type disperser, an ejector-type disperser, and a thin tube disperser for dispersing the particles of the core particle powder in the air Fine particle core particle powder particles having an average particle diameter of 10 μm or less in a frequency distribution or core particle powder particles mainly composed of fine particles are dispersed in the air to obtain a particle / gas mixture of highly dispersed core particle powder. Dispersion process,
(B) The degree of dispersity β, which is the ratio of the apparent primary particle weight of the particles of the core particle powder dispersed in this dispersion step to the coating start region of the coating space, is 70%. In the above dispersion state, it is directly discharged into the coating process, and is contacted and / or collided with the coating-forming material precursor, and (C) coated high-pressure boron nitride particles obtained by this coating process, or the same particles A method for producing a coated high-pressure boron nitride sintered body comprising a step of sintering the mixture at a pressure of 2000 MPa or more and at a high temperature. 前記被覆高圧型窒化硼素粒子が、被覆高圧型窒化硼素粒子の集合塊を解砕及び／又は破砕する工程及び／又はこの被覆高圧型窒化硼素粒子集合塊と一次粒子単位の被覆高圧型窒化硼素粒子とを選択分離する選択分離工程を更に経て調製されることを特徴とする、請求項１に記載の被覆高圧型窒化硼素焼結体の製造法。  The coated high-pressure boron nitride particles pulverize and / or crush aggregates of the coated high-pressure boron nitride particles and / or the coated high-pressure boron nitride particles and the primary high-pressure boron nitride particles in units of primary particles. 2. The method for producing a coated high-pressure boron nitride sintered body according to claim 1, further comprising a selective separation step of selectively separating the two. 前記芯粒子粉体の粒子が、溶融塩浴を用いる浸漬法により、浸漬法に由来する被覆物質で一層以上被覆された、微粒子芯粒子粉体の粒子又は主に微粒子からなる芯粒子粉体の粒子であることを特徴とする、請求項１又は請求項２に記載の被覆高圧型窒化硼素焼結体の製造法。  The core particle powder particles are coated with one or more coating materials derived from the immersion method by an immersion method using a molten salt bath, or a core particle powder mainly composed of fine particles. The method for producing a coated high-pressure boron nitride sintered body according to claim 1 or 2, wherein the method is a particle. 前記焼結工程は、（Ａ）高圧型窒化硼素の熱力学的安定領域で、及び／又は（Ｂ）動的及び／又は静的な２０００MPa以上の超高圧力・高温下で行われること
を特徴とする、請求項１、請求項２又は請求項３に記載の被覆高圧型窒化硼素焼結体の製造法。The sintering step is performed in (A) a thermodynamically stable region of high-pressure boron nitride and / or (B) a dynamic and / or static ultrahigh pressure / high temperature of 2000 MPa or more. The method for producing a coated high-pressure boron nitride sintered body according to claim 1, claim 2, or claim 3. 被覆高圧型窒化硼素粒子が、平均粒子径が１０μｍ以下の芯粒子粉体を、微粒子高分散処理手段群の最終処理により気中に分散させて、その芯粒子粉体の粒子の分散度βを７０％以上とする分散性能を有する微粒子高分散処理手段群による分散工程の一部以上と前記被覆工程の一部以上とを、空間を一部以上共有して行うことにより調製されることを特徴とする、請求項１に記載の被覆高圧型窒化硼素焼結体の製造法。  In the coated high-pressure boron nitride particles, the core particle powder having an average particle size of 10 μm or less is dispersed in the air by the final treatment of the fine particle high dispersion treatment means group, and the dispersion degree β of the particles of the core particle powder is determined. It is prepared by performing at least a part of the dispersion step by the fine particle high dispersion treatment means group having a dispersion performance of 70% or more and a part or more of the coating step while sharing a part of the space. The method for producing a coated high-pressure boron nitride sintered body according to claim 1. 被覆高圧型窒化硼素粒子が、平均粒子径が１０μｍ以下の芯粒子粉体を、微粒子高分散処理手段群の最終処理により気中に分散させて、その芯粒子粉体の粒子の分散度βを７０％以上とする空間領域の内の、高分散芯粒子粉体の粒子・気体混合物中の芯粒子粉体の粒子の全ての粒子が通過する面を含む空間領域に、被覆空間の被覆開始領域を位置せしめるか、又は平均粒子径が１０μｍ以下の芯粒子粉体を、微粒子高分散処理手段群の最終処理により気中に分散させて、その芯粒子粉体の粒子の分散度βを７０％以上とする空間領域の内の、回収手段の回収部に回収する全ての粒子が通過する面を含む空間領域に、被覆空間の被覆開始領域を位置せしめることにより調製されることを特徴とする、請求項１又は請求項５に記載の被覆高圧型窒化硼素焼結体の製造法。  In the coated high-pressure boron nitride particles, the core particle powder having an average particle size of 10 μm or less is dispersed in the air by the final treatment of the fine particle high dispersion treatment means group, and the dispersion degree β of the particles of the core particle powder is determined. A coating start region of the coating space in a spatial region including a surface through which all of the particles of the core particle powder in the particle / gas mixture of the highly dispersed core particle powder in the space region of 70% or more pass. Or a core particle powder having an average particle diameter of 10 μm or less is dispersed in the air by the final treatment of the fine particle high dispersion treatment means group, and the degree of dispersion β of the core particle powder is 70%. Of the above-described space region, it is prepared by positioning a coating start region of the coating space in a space region including a surface through which all particles collected by the collecting unit of the collecting unit pass, The coated high-pressure nitriding according to claim 1 or 5. The process of the sintered body. 使用する芯粒子粉体の粒子の粒度分布が、平均粒子径をＤ_Mとしたとき、体積基準頻度分布で（〔Ｄ_M／５，５Ｄ_M〕，≧９０％）であることを特徴とする、請求項１、請求項５又は請求項６に記載の被覆高圧型窒化硼素焼結体の製造法。The particle size distribution of the core particle powder to be used is a volume-based frequency distribution ([D _M / 5, 5 D _M ], ≧ 90%) where the average particle diameter is D _M. A method for producing a coated high-pressure boron nitride sintered body according to claim 1, claim 5 or claim 6. 分散手段が、さらに、芯粒子粉体の粒子を気中に分散させた芯粒子粉体の粒子と気体との混合物において低分散芯粒子粉体部分を分離し、芯粒子粉体の粒子が主に単一粒子状態で気中に存在する高分散芯粒子粉体の粒子・気体混合物を選択する高分散芯粒子粉体の粒子・気体混合物選択手段と、この高分散芯粒子粉体の粒子・気体混合物選択手段により選択分離された低分散芯粒子粉体部分を準微粒子高分散処理手段群中の分散手段の内の最終分散手段及び／又は最終分散手段以前の処理手段に搬送するフィードバック手段を有することを特徴とする、請求項１ないし請求項７に記載の被覆高圧型窒化硼素焼結体の製造法。  The dispersing means further separates the low-dispersion core particle powder part in the mixture of the core particle powder particles and the gas in which the core particle powder particles are dispersed in the air, and the core particle powder particles are mainly used. A highly dispersed core particle powder particle / gas mixture selection means for selecting a particle / gas mixture of the highly dispersed core particle powder existing in the air in a single particle state, A feedback means for conveying the low dispersion core particle powder portion selectively separated by the gas mixture selection means to the final dispersion means in the dispersion means in the quasi-fine particle high dispersion treatment means group and / or the processing means before the final dispersion means; The method for producing a coated high-pressure boron nitride sintered body according to any one of claims 1 to 7, characterized by comprising: 請求項１ないし請求項８に記載の被覆高圧型窒化硼素焼結体の製造法により製造した被覆高圧型窒化硼素焼結体。  A coated high-pressure boron nitride sintered body produced by the method for producing a coated high-pressure boron nitride sintered body according to claim 1.

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