JPS6172606A - Production of hexagonal boron nitride with good sintering properties - Google Patents

Abstract

PURPOSE:The addition of a Ca-containing compound to starting materials for synthesizing boron nitride is followed by heat treatment to cause nitridation and from a complete mixture of the boron nitride and the Ca-containing compound whereby hexagonal boron nitride with good sintering properties is obtained. CONSTITUTION:A mixture of a boron compound such as boric acid, ammonium borate and a nitrogen compound such as urea, ammonium chloride is combined with a Ca-containing compound such as its carbonate, hydroxide or oxide and the resultant mixture is heat-treated in a non-oxidative atmosphere at 250-600 deg.C to form lumps of the product. The product is crushed into particles of less than 50mm particle sizes, then the particles are heated in a non-oxidative atmosphere at 800-1,200 deg.C to obtain hexagonal boron nitride containing calcium compounds less than 9%, calculated as Ca atom and showing good sintering properties. The sintering process is preferably effected in a non-oxidative atmosphere under reduced pressure.

Description

【発明の詳細な説明】 〔ｆＩｉズ上の利用分野〕 本発明は、焼結特性の優れた六方晶窒化１ａｌ素の製造
方法に関する．さらに詳しく述べると、窒化硼素焼結体
製造用の原料粉末の製造法に関するものであり、Ｃａ含
有化合物を窒化硼素合成用の原料中に添加した後窒化反
応を生ぜしめ．Ｃａ含有化合物が窒化硼素と均一で完全
に混合した状態となっている、焼結性の優れた、窒化硼
素焼結体製造用原料を製造する方法に係る。DETAILED DESCRIPTION OF THE INVENTION [Field of application in terms of fIi] The present invention relates to a method for producing hexagonal 1al nitride having excellent sintering properties. More specifically, it relates to a method for producing a raw material powder for producing a boron nitride sintered body, in which a Ca-containing compound is added to a raw material for boron nitride synthesis, and then a nitriding reaction is caused. The present invention relates to a method for producing a raw material for producing a boron nitride sintered body, which has excellent sinterability, in which a Ca-containing compound is uniformly and completely mixed with boron nitride.

〔従来の技術〕[Conventional technology]

大方晶窒化硼素は白色の粉体で黒鉛と同様に六方晶の層
状構造であり，多種の特性を有している．特に熱伝導性
，電気絶縁性，耐食性、潤滑性，耐熱性，機械加工性な
どが優れており、これらの性質を生かして多岐の用途に
供されている。Orthogonal boron nitride is a white powder with a hexagonal layered structure similar to graphite, and has various properties. In particular, it has excellent thermal conductivity, electrical insulation, corrosion resistance, lubricity, heat resistance, machinability, etc., and it is used in a wide variety of applications by taking advantage of these properties.

粉体としての用途には、プラスチック添加剤、間滑剤な
どがあり，成形体および複合材としては。Applications as a powder include plastic additives and lubricants, and as molded objects and composite materials.

治具，？ｆ気絶縁材、型材などの用途がある。jig,? It has uses such as insulation materials and mold materials.

このよに用途の広い窒化硼Ｊ（以下ＢＮという）を合成
する方法は種々考案されているが，現在工業的に採用さ
れている方法は。Various methods have been devised for synthesizing boron nitride J (hereinafter referred to as BN), which has such a wide range of uses, but this method is currently used industrially.

（１）硼砂と尿十のｎ合物をアンモニア雰囲気中で８０
０℃以上に加熱合成する方法（特公昭３８−１６１０）
　。(1) 80% n-compound of borax and urine in an ammonia atmosphere
Method of heating synthesis above 0°C (Special Publication Publication No. 38-1610)
.

（２）硼醜、酸化硼＾と燐酸カルシウムと混合しアンモ
ニア雰囲気中で加熱する方法、 （３）　Ｆｌｉ酸と含窒素化合物（尿素、メラミン、シ
ソアンジアミドなと）をｔｓｏｏ℃以上に加熱する方法
（特公昭４８−１４５５９） などが主なものである。(2) A method of mixing boron oxide and calcium phosphate and heating the mixture in an ammonia atmosphere; (3) heating Fli acid and nitrogen-containing compounds (such as urea, melamine, and shisoandiamide) to temperatures above 20°C. The main methods include the method (Special Publication No. 48-14559).

その他に３塩化＋１素とアンモニアによる気相合成法も
あるが原料と製造コストが高いので特殊な用途に限られ
る。There is also a gas phase synthesis method using trichloride + 1 element and ammonia, but it is limited to special applications because of the high raw material and manufacturing costs.

また上記（３）の方法では結晶が成長しないので、この
欠点を改良する目的でアルカリ土類金属を添加して結晶
を成長させる方法（特公昭４１−１８５７０）が提案さ
れている。In addition, since crystals do not grow in the method (3) above, a method of growing crystals by adding an alkaline earth metal has been proposed (Japanese Patent Publication No. 41-18570) in order to improve this drawback.

ざらにＢＮ粉末にアルカリ土類金属の硼酸塩を混合して
焼結体製造用粉末を合成し、この粉末をホットプレスし
て焼結体を製造する方法（特公昭、＋　　　　　　　　
　　４９−４０１２４）がある。A method of mixing BN powder with an alkaline earth metal borate to synthesize a powder for producing a sintered body, and then hot pressing this powder to produce a sintered body (Tokukosho, +
49-40124).

〔発明が解決しようとする問題点〕[Problem that the invention seeks to solve]

上記（１）の方法は原料中の硼砂にナトリウム化合物を
含んでいるために１０００℃以上にするとナトリウム化
合物のノ％発が始まり反応炉に使用されている材料を傷
つけるのでｔｏｏｏ℃以下で一度水洗してナトリウム成
分を除去する必要がある。このため洗浄工程が必要にな
り工程が複雑になる。In method (1) above, since the borax in the raw material contains sodium compounds, if the temperature exceeds 1000℃, the sodium compounds will begin to emit % and will damage the materials used in the reactor, so wash once at a temperature below 100℃. It is necessary to remove the sodium component. Therefore, a cleaning step is required, which complicates the process.

上記（２）の方法も同様に添加した燐酸カルシウムを酸
洗して除去する必要がある。In the method (2) above, it is also necessary to remove the added calcium phosphate by pickling.

また上記（３）の方法については、１６００℃以上の高
温にしないと高純度品が製造できない。Furthermore, in the method (3) above, a high-purity product cannot be produced unless the temperature is raised to 1600° C. or higher.

アルカリ土類金属を添加して結晶を成長させる方法も上
記（３）と同様に添加物除去のため酸洗処理が必要であ
り、熱処理温度も１２００℃以上に加熱する必要がある
。Similarly to (3) above, the method of growing crystals by adding alkaline earth metals requires pickling treatment to remove additives, and the heat treatment temperature also needs to be heated to 1200° C. or higher.

またホットプレス法はＢＮ粉に助剤を添加しボールミル
などにより機械的混合する方法であるので、完全に混合
するには長時間を要する。またこのような方法によって
製造する場合、焼結体原料粉用のＢＮ粉末中のＢ２Ｏ３
などの不純物の含有量の変動、ＢＮ粉末の結晶の大きさ
の変動、混合の４１分さなどにより、均一・な原料粉が
得難い欠点を有する。またそのようにして得られた焼結
体強度、＃熱特性などは低い値を示し、かつ測定値の変
動も大きいことから根本的な改善が望まれていた。In addition, since the hot press method is a method in which an auxiliary agent is added to the BN powder and mechanically mixed using a ball mill or the like, it takes a long time to mix completely. In addition, when manufacturing by such a method, B2O3 in the BN powder for the raw material powder of the sintered body
It has the drawback that it is difficult to obtain a uniform raw material powder due to fluctuations in the content of impurities such as, fluctuations in the crystal size of the BN powder, and the length of mixing. Furthermore, the strength, thermal properties, etc. of the sintered body thus obtained showed low values, and the fluctuations in the measured values were large, so fundamental improvements were desired.

本発明は以上の実情に鑑みてなされたもので。The present invention has been made in view of the above circumstances.

酸洗等の複雑な工程を必要とせず、簡易に均質で焼結特
性の優れたＢＮの製造方法を提供することを目的とする
。The object of the present invention is to provide a simple method for producing BN that is homogeneous and has excellent sintering properties without requiring complicated steps such as pickling.

〔問題点を解決するための手段〕[Means for solving problems]

本発明者らは、従来技術の欠点を補うべく鋭意工夫を重
ねた結果、高純度でかつ結晶のあまり発達していない、
焼結体用原料として最適なりＮ粉末を製造するに至った
。The inventors of the present invention have made extensive efforts to compensate for the shortcomings of the conventional technology, and as a result, they have achieved high purity and poorly developed crystals.
We have now produced N powder that is optimal as a raw material for sintered bodies.

ＢＮ焼結体用の熱的および機械的特性を向上させるには
原料ＢＮとしては純度が高く結晶がＪ＆Ａしておらず粒
子の細かいものほど好ましい。In order to improve the thermal and mechanical properties of a BN sintered body, it is preferable that the raw material BN has a high purity, does not have J&A crystals, and has fine particles.

またＣａ含有化合物の添加により２５０〜６００″Ｃの
予備処理で強度の高い多孔質の予備処理物を得ることが
でき、この塊状のｆ−面処理生成物を使用して窒化処理
を行うと、従来の方法により合成したものよりＢＮ純度
の品いものが１１Ｉられる。In addition, by adding a Ca-containing compound, a porous pretreated product with high strength can be obtained by pretreatment at 250 to 600"C, and when this lumpy f-plane treatment product is used for nitriding, 11I can be obtained with higher BN purity than that synthesized by conventional methods.

本発明はこれらの知見により完成したもので硼素化合物
と窒素化合物の混合物に、Ｃａ含有化合物を添加し、こ
の混合物を非酸化性雰囲気中で２５０〜６００℃の温度
範囲で熱処理して塊状の生成物を生ぜしめ、該生成物を
５０ｍｍ以下の粒径に調整し、非酸化性雰囲気中で８０
０〜１２００℃までさらに加熱することによって、Ｃａ
が９％以下のＣａ化合物を含有する窒化硼素を製造する
ことを特徴とする。The present invention was completed based on these findings, and a Ca-containing compound is added to a mixture of a boron compound and a nitrogen compound, and this mixture is heat-treated at a temperature range of 250 to 600°C in a non-oxidizing atmosphere to form lumps. The product is adjusted to a particle size of 50 mm or less, and the product is heated at 80 mm in a non-oxidizing atmosphere.
By further heating from 0 to 1200°C, Ca
The present invention is characterized in that boron nitride containing a Ca compound of 9% or less is produced.

以下焼結体用原料として最適なりＮ粉末の製造方法につ
いて詳細に述べる。The method for producing N powder, which is most suitable as a raw material for sintered bodies, will be described in detail below.

硼素源としては種々なものが存在するが不純物の記入な
どを考慮すれば硼酸（およびその脱水物）、硼酸アンモ
ニウムなどの使用が適切であり、窒素源としては尿素、
メラミン、ジシアンジアミド、シアヌル酸、塩化アンモ
ニウムなどの高温で分解除去できるものとする。There are various boron sources, but boric acid (and its dehydrate), ammonium borate, etc. are appropriate if you take impurities into account, and as nitrogen sources, urea,
Materials that can be decomposed and removed at high temperatures, such as melamine, dicyandiamide, cyanuric acid, and ammonium chloride.

これらの原料の混合比は硼素源と窒素源のモル比（Ｎ／
Ｂ）が１以上になるように混合する心安がある。これら
の混合物の窒化をさらに進める目的で１例えば硼酸とジ
ンアンジアミドをＮ／Ｂ＝２になるように混合してアン
モニア雰囲気中で加熱したところ、９００℃でＢＮの含
有量は７０％程度、１２００℃でも８０％程度にしか窒
化反応は進んでいないことが明らかとなった。さらに窒
化反応を進めるべく検討した結果、原料と雰囲気ガスと
の接触が悪いことがＢＮの含壱景の向上しない原因と考
えられたので、４００℃でまず予備処理し、生成した多
孔質の塊状物質を使用してできるだけガスとの接触をよ
くして、各種熱処理炉（回転炉、プッシャー炉、竪型充
填炉）によりアンモニア雰囲気中で反応温度９００℃で
処理すると、上記反応と同一の試料でＢＮの純度が８５
〜９０％の生成物が得られた。The mixing ratio of these raw materials is determined by the molar ratio of boron source and nitrogen source (N/
It is safe to mix so that B) is 1 or more. In order to further nitridate these mixtures, for example, boric acid and dianediamide were mixed so that N/B=2 and heated in an ammonia atmosphere, and the BN content was about 70% at 900°C. It became clear that even at 1200°C, the nitriding reaction progressed only to about 80%. As a result of further study to proceed with the nitriding reaction, it was thought that poor contact between the raw material and the atmospheric gas was the reason for the lack of improvement in the BN content, so pre-treatment was first carried out at 400°C to reduce the porous mass produced. The same sample as in the above reaction was obtained by using a substance to improve contact with the gas as much as possible and treating it in an ammonia atmosphere at a reaction temperature of 900°C in various heat treatment furnaces (rotary furnace, pusher furnace, vertical filling furnace). BN purity is 85
~90% product was obtained.

、、１　　　　　　　　　さらに窒化率の向上を図り原
料の回収を向上させる目的で合成方法をさらに検討した
。まず予備処理温度での生成物から塊状の試料を取り出
すとさ、予備処理物が軟弱であるために塊状の生成物の
回収率が非常に悪く、５０％程度にしかならない、さら
にこの塊状生成物を反応炉に入れた場合に、一部の試料
は強度が弱いために反応炉の下部に入れられると、粉化
してしまい、気孔が閉塞し、ガスの流通が、占〈なり、
窒化率も向上せず。,,1 Furthermore, we further investigated the synthesis method with the aim of improving the nitriding rate and improving the recovery of raw materials. First, when a lump sample is taken from the product at the pretreatment temperature, the recovery rate of the lump product is very low, only about 50%, because the pretreatment material is soft. When placed in a reactor, some samples have weak strength, so if they are placed in the lower part of the reactor, they will turn into powder, the pores will be blocked, and the gas flow will be restricted.
The nitriding rate also did not improve.

また有機窒化物に含まれた炭素の析出も多くなる。この
ため使用する反応装置も制約を受けることとなった。Further, the precipitation of carbon contained in organic nitrides also increases. For this reason, the reaction equipment used was also subject to restrictions.

この点を解決するために、添加物により予備処理生成物
の強度を同上させ、かつ多孔質体の回収率の向上を図る
べく研究を進めた。その結果以下の結論に至った。つま
り添加物を選択する場合に次の２点がｆ！要である。In order to solve this problem, we conducted research to increase the strength of the pretreated product using additives and to improve the recovery rate of the porous material. As a result, we came to the following conclusion. In other words, when choosing additives, the following two points are f! It is essential.

（ａ）塊状予備処理生成物の回収率が高いこと。(a) High recovery rate of bulk pre-treated products.

（ｂ）　耐洗処理などにより添加物を除去しなくても、
そのまま含有した状態で焼結体の特性向上に役立つか、
または添加物が除去操作により完全に除去されず１部残
留した状態で焼結体を製造しても特性上問題がないこと
。(b) Even if additives are not removed by washing resistance treatment, etc.
Does it help improve the properties of the sintered body when contained as is?
Or, even if the sintered body is manufactured in a state where some of the additives are not completely removed by the removal operation and remain, there is no problem in terms of properties.

これらの条件を満足する添加物としてＣａ含有化合物（
炭酸塩、水醸化物、酸化物、燐酸塩など）が効果的であ
った。添加量についてはＣａ含イイ量が９％以下であれ
ば効果的であったが、Ｃａ含石着が９％を越えると、添
加物が焼結反応を生じ試料の多孔性が失われる状態にな
った。Ca-containing compounds (
carbonates, aqueous compounds, oxides, phosphates, etc.) were effective. Regarding the amount of addition, it was effective if the Ca content was 9% or less, but if the Ca content exceeded 9%, the additive would cause a sintering reaction and the porosity of the sample would be lost. became.

このと５の予備処理温度としては硼醜、硼酸ア／モニウ
ムの脱水には２５０℃以上を要し、尿素、メラミン、ジ
シアンジアミド、塩化アンモニウムなどの有ｍＷ化物を
完全に分解除去するためには６００℃まで加熱する必要
がある。そのため予備処理温度としては２５０〜６００
℃とした。The pretreatment temperature in step 5 is 250°C or higher for dehydration of am/monium borate, and 600°C or higher to completely decompose and remove mW compounds such as urea, melamine, dicyandiamide, and ammonium chloride. It is necessary to heat up to ℃. Therefore, the pretreatment temperature is 250 to 600.
℃.

予備処理生成物は十分にガスの流通が保証される５０ｍ
ｍ以下の粒度に粉砕し、酸化を防ぐために非酸化性雰囲
気、好ましくはアンモニア雰囲気中で窒化する必要があ
る。The pre-processed product is 50 m long to ensure sufficient gas flow.
It is necessary to grind the powder to a particle size of less than m and nitrided in a non-oxidizing atmosphere, preferably an ammonia atmosphere to prevent oxidation.

さらに高純度のＢＮを得るために実験を進める中で、合
成温度が高温になるとＢＨの含４量が向りするのは、硼
ふの窒化によってＢＮの含イＩ量が向上していくという
プロセスよりむしろ、酢化物として合成粉末中に存在し
ている酸化硼素の蒸発が大きく寄与していることが明ら
かになった。そこで減圧下で反応を生ぜしめることによ
り、酸化硼素の蒸発量も多くなり、ＢＮの含有量の向上
がみられた。While conducting experiments to obtain even higher-purity BN, it was discovered that as the synthesis temperature increases, the BH content increases because the I content of BN increases due to the nitriding of borium. It became clear that the evaporation of boron oxide, which is present in the synthetic powder as acetate, rather than the process, was the major contributor. Therefore, by causing the reaction under reduced pressure, the amount of evaporation of boron oxide increased, and an improvement in the BN content was observed.

予備処理した塊状生成物を非酸化性雰囲気中あるいは非
酸化性雰囲気の減圧下で熱処理する温度箱間は、８００
〜１２００℃とする。この理由としては、まず下限の８
００℃は、この温度未満であれば生成物中にＢＮに完全
になりきっていないボラジンなどの中間生成物が多量に
存在し、焼結体を製造するときに分解生成物が多く１粒
子の結合が弱くなり、焼結体用粉末としては不適となる
゛からである。上限を１２００℃としたのは、この温度
が第１図に示すようにＢＮの結晶が急に成長を始める限
界温度であり、焼結体用原料粉とじてはあまり粒子の成
長したものは好ましくないので、１２００℃以下に限定
した。特にＣａなとの存在トではこの傾向が大きく現わ
れ、１２００℃を越えると第１図に示すように、Ｃａ含
有量によっても結晶の大きさが異なってくるため均一な
焼結体用原料粉を得ることは難しい、このため多少のＣ
ａの含有量や温度の変動にも結晶の大きさが影響を受け
にくく、かつ粒度の細かい焼結体原料粉体として最も適
したＢＮを製造する温度穐囲として８００〜１２００℃
とした。The temperature range for heat treating the pretreated bulk product in a non-oxidizing atmosphere or under reduced pressure in a non-oxidizing atmosphere is 800°C.
~1200°C. The reason for this is that the lower limit of 8
If the temperature is lower than 00°C, there will be a large amount of intermediate products such as borazine that have not completely converted into BN in the product. This is because the bond becomes weak, making it unsuitable as a powder for sintered bodies. The upper limit was set at 1200°C because this temperature is the limit temperature at which BN crystals suddenly start to grow, as shown in Figure 1, and as raw material powder for sintered bodies, it is preferable that the particles grow too much. Therefore, the temperature was limited to 1200°C or lower. This tendency is especially noticeable when Ca is present, and as shown in Figure 1, when the temperature exceeds 1200℃, the crystal size changes depending on the Ca content, so it is difficult to make uniform raw material powder for sintered bodies. difficult to obtain, therefore some C
A temperature range of 800 to 1200°C is used to produce BN, which is most suitable as a raw material powder for sintered bodies with fine grain size and whose crystal size is not easily affected by changes in the content of a and temperature.
And so.

ＢＮ焼結体用原料中のＢＮの含有量と添加物のＣａ含イ
１化合物の特定については次の通りである。まず焼結体
中のＢＮ含有量については、高温Ｓ、Ｓ性などを考慮す
ると含有液が多いほどＩｌｆましく、ＢＮＮ含有量７０
％未満になると高温強度が急に低下するので７０％以上
とするのが適当である０合成粉末中のＣａの含有量とＢ
Ｎ含有量との関係は第２図に示すようになっている。従
って。The content of BN in the raw material for the BN sintered body and the specification of the Ca-containing compound as an additive are as follows. First, regarding the BN content in the sintered body, considering high-temperature S, S properties, etc., the more liquid it contains, the better Ilf is, and the BNN content is 70
If it is less than %, the high temperature strength will suddenly decrease, so it is appropriate to set it to 70% or more.0 Ca content in the synthetic powder and B
The relationship with N content is shown in Figure 2. Therefore.

’　　　　　　　　　Ｃａ含有量はＢＮの含有ｆｉ７０
％以上に対応する９％以下が好ましい。'Ca content is BN content fi70
It is preferably 9% or less, which corresponds to % or more.

このようにして５ＪｊＸｘしたＢＮ粉末は結晶粒子がサ
ブミクロンの状１ミになる活性なりＮである。The BN powder prepared in this way has an active N content in which the crystal grains are in the submicron size.

ざらに合成粉末よりＢＮの含右早を増加させ最適な焼結
体粉末を製造する目的で、酸洗、水洗によりＣａ含４１
量をコノトロールすることもｎ（能である。In order to increase the BN content quickly compared to the synthetic powder and produce an optimal sintered powder, the Ca content was reduced by pickling and water washing.
It is also possible to control the amount.

〔作用〕[Effect]

ＢＮ焼結体には３〜５％程度の８２０３が介在する。こ
のＢ２Ｏ３は大気中の水分によっていわ山る汗をかく現
象を生じて、Ｉａ酸を生成し体積変化を生じてＢＮ焼結
体の界面に割れを生じる。Approximately 3 to 5% of 8203 is present in the BN sintered body. This B2O3 causes a phenomenon of sweating due to the moisture in the atmosphere, generates Ia acid, causes a volume change, and causes cracks at the interface of the BN sintered body.

Ｃａは１２００℃以下の温度でこのＢ２Ｏ３と融体を生
成し、反応することによって１例えばＣａＯとＢ２０３
との化合物を生じ、この化合物はＢＮの焼結体の界面に
おいて接着剤のような作用をなすとともに、水分を吸収
することなくＢ２Ｏ３を安定化させる作用をなすものと
考えられる。従って本発明方法によって焼結特性の優れ
たＢＮを製造することができる。Ca forms a melt with this B2O3 at a temperature below 1200°C and reacts with 1, for example, CaO and B203.
It is thought that this compound acts like an adhesive at the interface of the BN sintered body, and also acts to stabilize B2O3 without absorbing moisture. Therefore, BN with excellent sintering properties can be produced by the method of the present invention.

〔発明の効果〕〔Effect of the invention〕

本発明により、簡易な工程と比較的低温において　高純
度で焼結特性の優れた窒化ｍ素を製造することが可Ｉ對
となった。According to the present invention, it has become possible to produce hydrogen nitride with high purity and excellent sintering properties through a simple process and at relatively low temperatures.

〔実施例〕〔Example〕

硼＃２ｋｇとジシアンジアミド２ｋｇに７￥酸カルシウ
ムを１４０ｇ添加し、内径４００ｍｍ＋６で高さ４００
ｍｍＨのポット炉でこの原料を窒素雰囲気中で４００℃
×１時間予備処理した。予備処理生成物を取り出し５〜
３０ｍｍに粒度調整した後、直径８０ｍｍφ、灼熱体長
さ４００　ｍ　ｍの回転炉に装入し、力σ熱源として製
鉄業から副生Ｊ＆物として得られるＣガスを使用してア
ンモニア雰囲気中で１ｏ００’ｃＸ２時間処理したとこ
ろ、生成した処理物はＢＮの含有量９３．３％であった
。この生成物を圧力２００　ｋ　ｇ　／　ｃゴで１９０
０℃×２時間のホットプレス処理により成形し成形体を
製造したところ、従来の市販のＢＨにＩＪＩＩＩ酸カル
シウム奢添加してホットプレスにより焼結体を製造する
方法に比べて高い強度のものがｔ７られた。Add 140g of calcium chloride to 2kg of boron #2 and 2kg of dicyandiamide, and make a mold with an inner diameter of 400mm + 6 and a height of 400mm.
This raw material was heated at 400°C in a nitrogen atmosphere in a mmH pot furnace.
Pretreatment was performed for ×1 hour. Take out the pre-treated product and
After adjusting the particle size to 30 mm, it was charged into a rotary furnace with a diameter of 80 mmφ and a scorching body length of 400 mm, and heated to 1000' in an ammonia atmosphere using C gas obtained as a by-product from the steel industry as a heat source. When treated with cX for 2 hours, the resulting treated product had a BN content of 93.3%. This product was dried at a pressure of 200 kg/c at 190
When a molded body was produced by hot pressing at 0°C for 2 hours, it was found that the strength was higher than that of the conventional method of producing a sintered body by hot pressing by adding a generous amount of calcium IJIII to commercially available BH. I got t7.

Ｃａ含イ１賃を各種変化させ製造したＢＮ原料を焼結し
て、これらを比較し、た値を：ＪＳ１表に示す。BN raw materials produced by varying the Ca content were sintered and compared, and the values are shown in Table JS1.

市販のＢＨにａｍカルシウムを添加したものの強度値は
本発明法によるものよりも低値を示した。この原因とし
ては原料の状態でＣａＩ＆分を添加することによって非
屑に細かいサブミクロンのＢＮ生成物と均一に混合でき
るが、市販あるいは合成したＢＮに１義カルシウムを添
湘してもボールミルなどの機械的な混合に頼らざるを得
ないために完全な混合物を得ることは難しいので、焼結
体の強度の向上が得られなかったものと考えられる。こ
のため特に高温における強度は、を発明により製品の方
が非常に優れて（・るといえる、また密度についても従
来品よりも高密度量が得られた。The strength value of commercially available BH to which am calcium was added was lower than that obtained by the method of the present invention. The reason for this is that by adding CaI in the raw material state, it is possible to mix it uniformly with fine submicron BN products without scraping, but even if primary calcium is added to commercially available or synthesized BN, it is not possible to use a ball mill or other method. It is considered that the strength of the sintered body could not be improved because it was difficult to obtain a complete mixture because mechanical mixing had to be relied upon. For this reason, it can be said that the product manufactured by the invention is extremely superior in strength, especially at high temperatures, and also has a higher density than conventional products.

４．１！４血の簡単な説明 第１図は窒化硼素の合成温度と合成結晶子の大きさとの
関係を示すグラフで、合成結晶子の大きさは７振炭素材
料１１７委員会資料の方法により測定したものである。4.1!4 Brief explanation of blood Figure 1 is a graph showing the relationship between the synthesis temperature of boron nitride and the size of synthesized crystallites. It was measured by.

第２図は合成粉中のＣａ含有量とＢＮ含有量との関係を
示すグラフである。FIG. 2 is a graph showing the relationship between Ca content and BN content in synthetic powder.

出　願　人　川ｌ＃製鉄株式会社 川崎炉材株式会社Applicant: Kawa I#Steel Co., Ltd. Kawasaki Rozai Co., Ltd.

Claims (1)

【特許請求の範囲】 １　硼素化合物と窒素化合物の混合物に、Ｃａ含有化合
物を添加し、この混合物を非酸化性雰囲気中で２５０〜
６００℃の温度範囲で熱処理して塊状の生成物を生ぜし
め、該生成物を５０ｍｍ以下の粒径に調整し、非酸化性
雰囲気中で８００〜１２００℃までさらに加熱すること
によって、Ｃａが９％以下のＣａ化合物を含有する窒化
硼素を製造することを特徴とする焼結特性の優れた六方
晶窒化硼素の製造方法。 ２　減圧下の非酸化性雰囲気中で加熱することを特徴と
する特許請求の範囲第１項に記載の製造方法。[Claims] 1. A Ca-containing compound is added to a mixture of a boron compound and a nitrogen compound, and the mixture is heated to
By heat-treating in the temperature range of 600°C to produce a lumpy product, adjusting the product to a particle size of 50 mm or less, and further heating to 800-1200°C in a non-oxidizing atmosphere, Ca is reduced to 9. A method for producing hexagonal boron nitride with excellent sintering properties, the method comprising producing boron nitride containing % or less of Ca compounds. 2. The manufacturing method according to claim 1, wherein heating is performed in a non-oxidizing atmosphere under reduced pressure.