JP5376274B2 - Method for producing highly conductive diamond sintered body - Google Patents
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この発明は、良導電性を有するダイヤモンド焼結体を、簡易な工程で効率的に製造する製造方法に関する。 The present invention relates to a production method for efficiently producing a diamond sintered body having good conductivity by a simple process.
従来から、ダイヤモンドは、硬度、熱伝導性、耐熱性が高く、化学安定性にすぐれていること等から、耐摩耗材料、電子デバイス・センサ材料、バイオ関連材料、光学関連材料等、幅広い分野に利用されており、そして、ダイヤモンドの製造法としては、各種ＣＶＤ法による気相合成法、超高圧高温装置を用いた合成法が多く利用されている。 Conventionally, diamond has high hardness, thermal conductivity, heat resistance, and excellent chemical stability, so it can be used in a wide range of fields such as wear-resistant materials, electronic device / sensor materials, bio-related materials, and optical-related materials. As a method for producing diamond, a gas phase synthesis method using various CVD methods and a synthesis method using an ultrahigh pressure and high temperature apparatus are often used.
ダイヤモンド自体が非導電性であることは一般に良く知られているが、近年、ダイヤモンドにボロンをドープしたボロンドープダイヤモンドが、その半導体的特性の点から注目を浴びており、そして、その製造方法としては、例えば、ダイヤモンドを合成する際に、反応ガス中に微量のボロン成分を添加する気相合成法、グラファイト粉末とボロン粉末を原料粉末として、これを５〜１０ＧＰａかつ１３００〜２０００℃の条件下で合成する超高圧高温合成法が知られている。 It is generally well known that diamond itself is non-conductive, but in recent years, boron-doped diamond obtained by doping boron into diamond has attracted attention in terms of its semiconducting properties, and as a method for producing the same. Is, for example, a gas phase synthesis method in which a small amount of boron component is added to a reaction gas when synthesizing diamond. An ultra-high pressure and high-temperature synthesis method is known which is synthesized by the above method.
また、ダイヤモンド自体の有する硬度、耐摩耗性等の特性に着目して、ダイヤモンド焼結体が切削工具材料等として用いられているが、通常、ダイヤモンド焼結体は、超高圧高温条件下の焼結で製造され、例えば、ダイヤモンド粉末とＣｏ粉末を原料粉末として、超高圧高温装置内で５．５ＧＰａの圧力下１５００℃の条件で焼結することによりダイヤモンド−Ｃｏ系焼結体を得る方法、ダイヤモンド粉末とＴｉ、Ｚｒ、Ｃｒ等の粉末からなる原料粉末を、超高圧高温装置内で６．５ＧＰａ以上に加圧し１７００〜１９００℃の条件で焼結し、その後さらに２０００℃以上の温度で加熱することにより、ダイヤモンド−セラミックス系焼結体を得る方法、ダイヤモンド粉末と炭酸塩粉末を原料粉末として、超高圧高温装置内で６〜１２ＧＰａの圧力下、１７００〜２５００℃の条件で焼結することにより、ダイヤモンド−炭酸塩系焼結体を得る方法等が知られている。
ダイヤモンド焼結体は、その特性を生かし幅広い分野に利用されているが、例えば、上記従来技術と示したダイヤモンド−Ｃｏ系焼結体においては、結合相が金属Ｃｏで構成されているために導電性を備え、そのため放電加工等による焼結体の加工が可能であるという利点はあるものの、結合相が金属Ｃｏであるが故に耐熱性が低いという弱点があった。一方、上記従来技術と示したダイヤモンド−炭酸塩系焼結体においては、その耐熱性は非常に優れているものの、導電性を有さないために、放電加工を行うことができず、レーザ加工によって加工せざるを得ないという加工上の難点があった。
このように、従来技術においては、良導電性を備えるとともに、ダイヤモンドに匹敵するその他の特性（硬度、熱伝導性、耐熱性、化学安定性等）をも備えたダイヤモンド焼結体を得ることは非常に困難であったため、これがダイヤモンド焼結体の幅広い分野への応用を妨げる一つの要因とされていた。
そこで、この発明では、良導電性を有するとともに、硬度、熱伝導性、耐熱性、化学安定性等についても天然ダイヤモンドに匹敵する特性を備えたダイヤモンド焼結体を、簡易な工程で効率的に製造することを目的とする。
The diamond sintered body is used in a wide range of fields by taking advantage of its characteristics. For example, in the diamond-Co based sintered body shown as the above prior art, since the binder phase is composed of metal Co, it is conductive. Although there is an advantage that the sintered body can be processed by electric discharge machining or the like, there is a weak point that heat resistance is low because the binder phase is metallic Co. On the other hand, in the diamond-carbonate sintered body shown as the above prior art, although its heat resistance is very excellent, since it has no electrical conductivity, electric discharge machining cannot be performed, and laser machining is performed. There was a processing difficulty that had to be processed.
Thus, in the prior art, it is possible to obtain a diamond sintered body having good conductivity and other characteristics (hardness, thermal conductivity, heat resistance, chemical stability, etc.) comparable to diamond. Since it was very difficult, this was regarded as one factor that hinders the application of sintered diamonds to a wide range of fields.
Therefore, in the present invention, a diamond sintered body having good conductivity and hardness, thermal conductivity, heat resistance, chemical stability, etc. comparable to natural diamond can be efficiently produced by a simple process. The purpose is to manufacture.
本発明者らは、かかる課題を解決すべく、ダイヤモンド焼結体を製造する際の原料粉末および焼結工程について鋭意研究を行なったところ、
（ａ）焼結体を得るための原料粉末として、ダイヤモンド粉末と、ボロン粉末と、焼結体の結合相を形成する成分として、Ｍｇ、Ｃａ、Ｓｒ、Ｂａの炭酸塩並びにこれらの２種以上の複合炭酸塩のうちの１種または２種以上の炭酸塩（以下、これらを総称して、単に「アルカリ土類炭酸塩」という）粉末を使用し、各粉末を所定量配合し、それを混合して原料粉末を用意し、原料粉末を超高圧高温条件下で焼結するにあたり、まず第１段階として、所定圧所定温度で混合粉末中のボロンをダイヤモンドへ拡散させる拡散処理を行い、次ぎに、第２段階として、より高圧高温条件下で、結合相成分であるアルカリ土類炭酸塩粉末を溶融させ、ボロンが拡散したダイヤモンド粉末の粒子間隙に溶融した結合相成分を溶浸・充填させると、これによって良導電性を備えたダイヤモンド焼結体が得られること。
（ｂ）即ち、天然ダイヤモンドそれ自体の電気伝導度は、１０−５Ｓ／ｃｍ以下と非常に低いものである。一方、ボロンドープダイヤモンド粉末の電気伝導度は非常に高く、約１．５Ｓ／ｃｍである。また、上記従来技術におけるダイヤモンド−炭酸塩系焼結体の電気伝導度も、約１０−５Ｓ／ｃｍ程度と小さい値であるのに対して、上記（ａ）の製造法によって得られたダイヤモンド焼結体では、約１．０〜１０−２Ｓ／ｃｍの電気伝導度を有しており、ダイヤモンド−Ｃｏ系焼結体の電気伝導度約２×１０−２Ｓ／ｃｍとほぼ同等の良導電性を備えることから、放電加工で焼結体を加工しようとする場合に必要とされる十分な良導電性を備えたものであること。
（ｃ）また、ダイヤモンド−Ｃｏ系焼結体のように、焼結体中に金属成分の結合相を含有するものでは、７００℃程度の耐熱性しか備えていないのに対して、上記（ａ）の製造法によって得られたダイヤモンド焼結体では、約１２００℃であって、非常に優れた耐熱性を有し、さらに、硬度、熱伝導性、化学安定性についても非常に優れた特性値を示すこと。
という上記（ａ）〜（ｃ）の知見を得たのである。
In order to solve such problems, the present inventors conducted earnest research on the raw material powder and the sintering process when producing a diamond sintered body.
(A) As raw material powder for obtaining a sintered body, diamond powder, boron powder, and carbonate, Mg, Ca, Sr, and Ba, as a component that forms a binder phase of the sintered body, and two or more of these 1 or 2 or more types of carbonates (hereinafter collectively referred to simply as “alkaline earth carbonates”) powders, and each powder is mixed in a predetermined amount. When mixing raw material powder and sintering the raw material powder under ultra-high pressure and high temperature conditions, first, as a first step, a diffusion treatment is performed to diffuse boron in the mixed powder into diamond at a predetermined pressure and a predetermined temperature. As a second stage, the alkaline earth carbonate powder as the binder phase component is melted under higher pressure and high temperature conditions, and the molten binder phase component is infiltrated and filled in the interstices of the diamond powder in which boron has diffused. And this The diamond sintered body is obtained having a good conductivity Te.
(B) That is, the electrical conductivity of natural diamond itself is as low as 10 −5 S / cm or less. On the other hand, the conductivity of boron-doped diamond powder is very high, about 1.5 S / cm. Further, the electrical conductivity of the diamond-carbonate-based sintered body in the prior art is as small as about 10 −5 S / cm, whereas the diamond obtained by the production method (a) above is used. the sintered body of approximately equal to about 1.0 to 10 -2 S / cm of have an electrical conductivity of about 2 × 10 -2 S / cm electrical conductivity of the diamond -Co-based sintered body Since it has good conductivity, it must have sufficient good conductivity required when processing a sintered body by electric discharge machining.
(C) Also, a sintered body containing a binder phase of a metal component, such as a diamond-Co based sintered body, has only a heat resistance of about 700 ° C., whereas the above (a The diamond sintered body obtained by the manufacturing method of) has a very excellent heat resistance at about 1200 ° C., and also has excellent characteristics such as hardness, thermal conductivity, and chemical stability. Showing.
The above findings (a) to (c) were obtained.
この発明は、上記知見に基づいてなされたものであって、
「ダイヤモンド粉末８０〜９９．４ｗｔ％と、ボロン粉末０．５〜１５ｗｔ％と、結合相成分として、Ｍｇ、Ｃａ、Ｓｒ、Ｂａの炭酸塩並びにこれらの２種以上の複合炭酸塩のうちの１種または２種以上からなる炭酸塩粉末０．１〜１０ｗｔ％とを混合した原料粉末を超高圧高温発生装置に装入し、該超高圧高温発生装置内で、第１段階として、５．０〜８．０ＧＰａの加圧条件下で１３００〜１８００℃の温度に加熱してダイヤモンド粉末へのボロンの拡散を行い、その後、第２段階として、６．０〜９．０ＧＰａの加圧条件下で１６００〜２５００℃の温度に加熱して上記結合相成分を溶融させ、ボロンが拡散したダイヤモンド粉末粒子間隙に溶融した結合相成分を溶浸充填させることを特徴とする良導電性ダイヤモンド焼結体の製造方法。」
に特徴を有するものである。
This invention has been made based on the above findings,
“Diamond powder 80 to 99.4 wt%, boron powder 0.5 to 15 wt%, and Mg, Ca, Sr, Ba carbonate as a binder phase component and one of these two or more complex carbonates Raw material powder mixed with 0.1 to 10 wt% of carbonate powder composed of seeds or two or more species is charged into an ultrahigh pressure and high temperature generator, and within the ultrahigh pressure and high temperature generator, as a first step, 5.0 is added. The boron is diffused into the diamond powder by heating to a temperature of 1300-1800 ° C. under a pressure condition of ˜8.0 GPa, and then under a pressure condition of 6.0-9.0 GPa as a second stage. A highly conductive diamond sintered body characterized in that the binder phase component is melted by heating to a temperature of 1600 to 2500 ° C., and the melted binder phase component is infiltrated and filled in the gaps of the diamond powder particles in which boron has diffused. Manufacturing method . "
It has the characteristics.
以下に、この発明を、より具体的かつ詳細に説明する。 Hereinafter, the present invention will be described more specifically and in detail.
（１）ダイヤモンド粉末、ボロン粉末
ダイヤモンド粉末としては、気相合成法に限らず、現在既によく知られている方法で製造されたダイヤモンド粉末を使用することができる。
また、ボロン粉末としては、結晶性ボロン粉末あるいは非晶質ボロン粉末が望ましいが、場合によっては、ボロン含有量の高いボロンカーバイド粉末を使用することもできる。
そして、ボロン粉末におけるボロン成分は、超高圧高温条件下の焼結における第１段階、即ち、５．０〜８．０ＧＰａの加圧条件下で１３００〜１８００℃の温度範囲において、ボロンがダイヤモンド粉末の表面へ拡散する。こうして得られたダイヤモンド粉末は、最終的に得られるダイヤモンド焼結体に導電性を付与する作用を有する。
(1) Diamond powder and boron powder Diamond powder is not limited to gas phase synthesis, and diamond powder produced by a method already well known at present can be used.
As the boron powder, crystalline boron powder or amorphous boron powder is desirable, but in some cases, boron carbide powder having a high boron content can also be used.
The boron component in the boron powder is a first step in sintering under ultra-high pressure and high temperature, that is, boron is a diamond powder in a temperature range of 1300 to 1800 ° C. under a pressure of 5.0 to 8.0 GPa. Diffuses to the surface of The diamond powder obtained in this way has the effect | action which provides electroconductivity to the diamond sintered compact finally obtained.
（２）アルカリ土類炭酸塩粉末
ダイヤモンド粉末とボロン粉末とアルカリ土類炭酸塩粉末とを混合し、これを原料粉末として、超高圧高温条件下で焼結を行う際、第１段階として、５．０〜８．０ＧＰａの加圧条件下で１３００〜１８００℃の温度範囲での焼結により、ボロン成分のダイヤモンドへの拡散が生じ、次の第２段階、即ち、６．０〜９．０ＧＰａの加圧条件下１６００〜２５００℃の温度範囲での焼結によって、上記結合相成分が溶融し、溶融した結合相成分が、ボロンがドープしたダイヤモンド粉末粒子間隙に溶浸充填され、焼結体の密度を高める結合相として存在する。
(2) Alkaline earth carbonate powder When diamond powder, boron powder and alkaline earth carbonate powder are mixed and used as a raw material powder for sintering under ultrahigh pressure and high temperature conditions, the first stage is 5 Sintering in the temperature range of 1300-1800 ° C. under pressure conditions of 0.0-8.0 GPa causes the boron component to diffuse into the diamond, which is the second stage, ie 6.0-9.0 GPa. By sintering in the temperature range of 1600 to 2500 ° C. under the pressure conditions of the above, the above binder phase component is melted, and the melted binder phase component is infiltrated and filled into the gap between the boron-doped diamond powder particles, and the sintered body It exists as a binder phase that increases the density of.
（３）原料粉末の配合割合
この発明では、ダイヤモンド焼結体が、ダイヤモンドが本来有する硬度、熱伝導性、化学安定性というすぐれた特性を失わないで、かつ、良導電性をも保持するという観点から、原料粉末中のダイヤモンド粉末の配合割合を８０〜９９．４ｗｔ％と定め、また、ボロン粉末の配合割合を０．５〜１５ｗｔ％と定め、一方、ダイヤモンド焼結体に良導電性を付与させつつ、耐熱性を高め、さらに、所定の焼結体密度を保持するという観点から、アルカリ土類炭酸塩粉末の配合割合を０．１〜１０ｗｔ％と定めた。
つまり、ダイヤモンド粉末の配合割合が８０ｗｔ％未満、ボロン粉末の配合割合が０．５ｗｔ％未満、あるいは、アルカリ土類炭酸塩粉末の配合割合が１０ｗｔ％を超えた場合には、ダイヤモンド焼結体に所定の良導電性を付与できないばかりか、焼結体としての硬度、熱伝導性、化学安定性、緻密度が低下し、一方、アルカリ土類炭酸塩粉末の配合割合が０．１ｗｔ％未満、あるいは、ダイヤモンド粉末の配合割合が９９．４ｗｔ％を超えた場合またボロン粉末の配合割合が１５ｗｔ％を超えた場合には、結合相成分の減少による焼結性の低下、焼結体強度の低下とともに耐熱性が低下するようになるからである。
なお、原料粉末の配合にあたり、ダイヤモンド粉末、ボロン粉末、アルカリ土類炭酸塩粉末の各粉末を直接配合するのではなく、先行技術として示した方法により製造した（予めボロンをドープした）ボロンドープダイヤモンドをアルカリ土類炭酸塩粉末と配合し、これを原料粉末として焼結を行うことも考えられるが、ボロンドープダイヤモンドのダイヤモンド粒子内には、合成時に使用した金属触媒等の一部が不純物として残留していることがあり、この場合には焼結体の特性（例えば、耐熱性）に悪影響を及ぼし、また、合成で得られたボロンドープダイヤモンドは塊状であるため、これを破砕し、化学処理により金属不純物等の除去を行い、その後分級を行う必要があり、後工程での手間がかかる。それ故、原料粉末としては、ダイヤモンド粉末、ボロン粉末およびアルカリ土類炭酸塩粉末を、それぞれ所定割合で配合したものを使用することが必要である。そして、ダイヤモンド粉末、ボロン粉末、アルカリ土類炭酸塩粉末をそれぞれ所定割合で配合したものを原料粉末とすれば、ダイヤモンド粒子内への不純物の混入を防止できるばかりか、ボロンドープダイヤモンド合成後の後工程も不要になり、さらに、焼結体中のダイヤモンドとボロンの含有割合を、配合比の調整により的確かつ容易に設定することができる。
(3) Mixing ratio of raw material powder In this invention, the diamond sintered body does not lose excellent properties such as hardness, thermal conductivity, and chemical stability inherent in diamond, and also maintains good conductivity. From the viewpoint, the blending ratio of the diamond powder in the raw material powder is determined to be 80 to 99.4 wt%, and the blending ratio of the boron powder is determined to be 0.5 to 15 wt%. On the other hand, the diamond sintered body has good conductivity. From the viewpoint of increasing the heat resistance and maintaining a predetermined sintered body density while imparting, the blending ratio of the alkaline earth carbonate powder was determined to be 0.1 to 10 wt%.
That is, when the blending ratio of diamond powder is less than 80 wt%, the blending ratio of boron powder is less than 0.5 wt%, or the blending ratio of alkaline earth carbonate powder exceeds 10 wt%, Not only can the predetermined good conductivity not be imparted, but also the hardness, thermal conductivity, chemical stability and density as a sintered body are reduced, while the blending ratio of alkaline earth carbonate powder is less than 0.1 wt%, Alternatively, when the blending ratio of the diamond powder exceeds 99.4 wt% and when the blending ratio of the boron powder exceeds 15 wt%, the sinterability decreases due to the decrease in the binder phase component, and the sintered body strength decreases. It is because heat resistance will fall with it.
Boron-doped diamond produced by the method shown in the prior art (previously doped with boron), instead of directly blending each powder of diamond powder, boron powder, and alkaline earth carbonate powder when blending the raw material powder It is conceivable to mix with alkaline earth carbonate powder and sinter using this as raw material powder. However, some of the metal catalyst used during synthesis remains as impurities in the diamond particles of boron-doped diamond. In this case, it adversely affects the properties of the sintered body (for example, heat resistance), and the boron-doped diamond obtained by synthesis is agglomerated, so it is crushed and chemically treated. Thus, it is necessary to remove metal impurities and the like, and then perform classification, which takes time in subsequent steps. Therefore, as the raw material powder, it is necessary to use a mixture of diamond powder, boron powder and alkaline earth carbonate powder in a predetermined ratio. If the raw material powder is a mixture of diamond powder, boron powder, and alkaline earth carbonate powder in predetermined proportions, not only can impurities be prevented from entering the diamond particles, but also after boron-doped diamond synthesis. A process is also unnecessary, and the content ratio of diamond and boron in the sintered body can be accurately and easily set by adjusting the mixing ratio.
（４）超高圧高温装置における焼結条件
超高圧高温装置による焼結において、その第１段階として５．０〜８．０ＧＰａの加圧条件下で１３００〜１８００℃の温度範囲において、ダイヤモンド粉末へのボロンの拡散が生じ、これによって、焼結体に導電性を付与することができるが、加圧条件、加熱温度条件が上記範囲未満であると、ボロンの拡散が不十分になり、焼結体に満足できる導電性を付与することができず、また、加圧条件、加熱温度条件が上記範囲を超えると、炭酸塩が溶融しはじめてボロン拡散相が十分に形成されないままダイヤモンドが焼結されることから、焼結第１段階における加圧条件、加熱温度を、それぞれ、５．０〜８．０ＧＰａ、１３００〜１８００℃と定めた。
また、第２段階の焼結において、加圧圧力が６．０ＧＰａ未満では十分な緻密化が図れず、また、その効果は９．０ＧＰａ以下で十分であり、それを超えると装置コストが高くなるので、加圧圧力は６．０〜９．０ＧＰａと定めた。さらに、加熱温度が１６００℃未満では、アルカリ土類炭酸塩の溶融、溶浸、充填が不十分になるとともに焼結反応も不十分であるため焼結体の緻密化を図れず、一方、加熱温度が２５００℃を超えると過焼結状態となり、ダイヤモンド粒子がグラファイト化する現象が生じることから、加熱温度を１６００〜２５００℃と定めた。
なお、原料粉末を超高圧高温発生装置に装入するにあたり、この発明では、ダイヤモンド粉末、ボロン粉末およびアルカリ土類炭酸塩粉末を混合し、この混合粉末を原料粉末として超高圧高温発生装置内へ装入するとしたが、原料粉末を混合粉末とせずに、ダイヤモンド粉末、ボロン粉末、アルカリ土類炭酸塩粉末のそれぞれが粉末層を形成し、この粉末層が積層された状態の原料粉末を、超高圧高温発生装置内に装入した状態で焼結を行うことも勿論可能である。
(4) Sintering conditions in an ultra-high pressure and high-temperature apparatus In the sintering in an ultra-high pressure and high-temperature apparatus, as a first step, to a diamond powder in a temperature range of 1300 to 1800 ° C under a pressure condition of 5.0 to 8.0 GPa. Boron diffusion occurs, and this makes it possible to impart conductivity to the sintered body. However, if the pressurizing condition and heating temperature condition are less than the above ranges, the boron diffusion becomes insufficient, and the sintered body is sintered. The body cannot be provided with satisfactory conductivity, and when the pressurization and heating temperature conditions exceed the above ranges, the carbonate starts to melt and the diamond is sintered without the boron diffusion phase being sufficiently formed. Therefore, the pressurizing condition and the heating temperature in the first stage of sintering were set to 5.0 to 8.0 GPa and 1300 to 1800 ° C., respectively.
In addition, in the second stage sintering, if the pressure is less than 6.0 GPa, sufficient densification cannot be achieved, and the effect is sufficient if the pressure is 9.0 GPa or less. Therefore, the pressurizing pressure was determined to be 6.0 to 9.0 GPa. Furthermore, if the heating temperature is less than 1600 ° C., the alkaline earth carbonate is insufficiently melted, infiltrated and filled, and the sintering reaction is insufficient, so that the sintered body cannot be densified. When the temperature exceeds 2500 ° C., the oversintering state occurs, and the phenomenon that the diamond particles are graphitized occurs. Therefore, the heating temperature was set to 1600 to 2500 ° C.
In addition, when charging the raw material powder into the ultra-high pressure and high-temperature generator, in the present invention, diamond powder, boron powder and alkaline earth carbonate powder are mixed, and this mixed powder is used as the raw powder into the ultra-high pressure and high-temperature generator. Although the raw material powder is not mixed powder, each of diamond powder, boron powder, and alkaline earth carbonate powder forms a powder layer. Of course, it is also possible to perform the sintering in a state of being charged in the high-pressure and high-temperature generator.
この発明のダイヤモンド焼結体の製造方法によれば、ダイヤモンド粉末、ボロン粉末と、焼結体の結合相を形成するアルカリ土類炭酸塩粉末とを、超高圧高温条件下、その第１段階として、ボロンをダイヤモンドへ拡散させ導電性を付与し、そして、その第２段階として、結合相成分を溶融させて粒子間隙に溶浸充填させるという簡易かつ効率的な２段階の工程で良導電性を有するダイヤモンド焼結体を得ることができる。
そして、この発明により製造したダイヤモンド焼結体は、良導電性ばかりか、すぐれた耐熱性を備え、さらに、硬度、熱伝導性、化学安定性については天然ダイヤモンドに匹敵する特性を備えるものであることから、放電加工で容易に加工できるという優れた加工特性を生かし、多方面への応用が期待されることから、実用上の効果は非常に大きい。
According to the method for producing a diamond sintered body of the present invention, diamond powder, boron powder, and alkaline earth carbonate powder forming a binder phase of the sintered body are used as the first stage under ultrahigh pressure and high temperature conditions. , Boron is diffused into diamond to provide conductivity, and as the second step, good electrical conductivity is achieved in a simple and efficient two-step process in which the binder phase component is melted and infiltrated and filled in the particle gaps. A diamond sintered body can be obtained.
The diamond sintered body produced according to the present invention has not only good conductivity but also excellent heat resistance, and further has properties comparable to natural diamond in terms of hardness, thermal conductivity and chemical stability. Therefore, it is expected to be applied in various fields by taking advantage of the excellent machining characteristics that it can be easily machined by electric discharge machining, so that the practical effect is very large.
表１に、この発明の実施例で使用したダイヤモンド粉末、ボロン粉末、アルカリ土類炭酸塩粉末の具体例を示す。 Table 1 shows specific examples of diamond powder, boron powder, and alkaline earth carbonate powder used in the examples of the present invention.
表１に示される各種のダイヤモンド粉末、ボロン粉末およびアルカリ土類炭酸塩粉末を、表２に示される配合割合で混合し、原料粉末１〜１５を用意した。これらの原料粉末１〜１５を、通常のベルト型超高圧高温装置に装入し、本発明法１〜１５として、表３に示される条件で第一段階、第二段階の焼結を行い、表４に示されるダイヤモンド焼結体１〜１５（以下、本発明焼結体１〜１５という）を製造した。本発明法１〜１５により製造した本発明焼結体１〜１５の諸特性（電気伝導度（電気抵抗値）、耐熱性、硬度、熱伝導度、化学安定性等）を測定し、その測定値を表４に示す。 Various diamond powders, boron powders, and alkaline earth carbonate powders shown in Table 1 were mixed at a blending ratio shown in Table 2 to prepare raw material powders 1-15. These raw material powders 1 to 15 are charged into a normal belt-type ultra-high pressure and high temperature apparatus, and as the present invention methods 1 to 15, the first stage and second stage sintering are performed under the conditions shown in Table 3, Diamond sintered bodies 1 to 15 shown in Table 4 (hereinafter referred to as the present invention sintered bodies 1 to 15) were produced. Various properties (electric conductivity (electric resistance value), heat resistance, hardness, thermal conductivity, chemical stability, etc.) of the sintered bodies 1 to 15 of the present invention produced by the present invention methods 1 to 15 are measured and measured. Values are shown in Table 4.
比較の目的で、原料粉末１、５、１０を使用して、比較法１、５、１０として表５に示される条件で焼結を行い、比較焼結体１、５、１０を製造した。その諸特性を表６に示す。
また、参考のため、従来法１（特表２００６−５０２９５５号公報記載の方法）により製造したボロンドープダイヤモンド焼結体（従来焼結体１という）、および従来法２（特許第２７９５７３８号明細書）により製造したダイヤモンド−炭酸塩系焼結体（従来焼結体２という）についても、その諸特性を同じく表６に示す。
For the purpose of comparison, raw powders 1, 5, and 10 were used, and sintering was performed under the conditions shown in Table 5 as comparative methods 1, 5, and 10 to produce comparative sintered bodies 1, 5, and 10. Table 6 shows the characteristics.
For reference, a boron-doped diamond sintered body (referred to as the conventional sintered body 1) manufactured by the conventional method 1 (the method described in JP 2006-502955 A) and a conventional method 2 (Japanese Patent No. 2795738) Table 6 also shows the characteristics of the diamond-carbonate-based sintered body (referred to as “conventional sintered body 2”) manufactured by the above method.
なお、上記実施例、比較例において、電気伝導度（電気抵抗値）、耐熱性及び化学安定性の評価は次のようにして行った。
電気伝導度評価試験；４端子法により電気抵抗を測定した。
耐熱性評価試験；真空炉にて、温度８００℃と１２００℃でそれぞれ保持時間３０分間の条件で熱処理する耐熱試験を行い、その後、ＸＲＤ（Ｘ線）分析により、熱処理後のグラファイト化（ダイヤモンドの逆変換）の有無を確認した。
化学安定性評価試験；焼結体を１５０℃の熱フッ酸に２時間浸漬し、焼結体の形状変化の有無を調べた。
In the above Examples and Comparative Examples, the electrical conductivity (electric resistance value), heat resistance and chemical stability were evaluated as follows.
Electrical conductivity evaluation test: Electrical resistance was measured by the 4-terminal method.
Heat resistance evaluation test: A heat resistance test is performed in a vacuum furnace at a temperature of 800 ° C. and 1200 ° C. with a holding time of 30 minutes, respectively. After that, by XRD (X-ray) analysis, graphitization after the heat treatment (diamond The presence or absence of reverse conversion was confirmed.
Chemical stability evaluation test: The sintered body was immersed in hot hydrofluoric acid at 150 ° C. for 2 hours, and the presence or absence of a shape change of the sintered body was examined.
表４、表６に示される本発明焼結体１〜１５と、比較焼結体１、５、１０および従来焼結体１、２の特性比較からも明らかなように、本発明法１〜１５で製造した本発明焼結体１〜１５は、良導電性とすぐれた耐熱性とを兼ね備え、さらに、硬度、熱伝導性、化学安定性についても天然ダイヤモンドに匹敵する特性を備えるのに対して、製造条件が本発明法から外れる比較法１、５、１０で製造した比較焼結体１、５、１０あるいは従来法１、２で製造した従来焼結体１、２は、導電性、熱伝導性、耐熱性、硬度、化学安定性の何れかが本発明焼結体１〜１５より劣っている。
以上の通り、本発明によれば、良導電性を有するダイヤモンド焼結体を簡易な工程で効率的に製造することができ、しかも、本発明の製造法により得たダイヤモンド焼結体は、放電加工による加工が十分可能である導電性を備えているので、ダイヤモンド焼結体の応用分野が広がり、実用上の効果はきわめて大である。
As is apparent from the comparison of the characteristics of the sintered bodies 1 to 15 of the present invention shown in Tables 4 and 6 and the comparative sintered bodies 1, 5 and 10 and the conventional sintered bodies 1 and 2, The sintered bodies 1 to 15 of the present invention produced in No. 15 have both good conductivity and excellent heat resistance, and also have properties comparable to natural diamond in terms of hardness, thermal conductivity, and chemical stability. The comparative sintered bodies 1, 5, 10 produced by the comparative methods 1, 5, 10, which have manufacturing conditions deviating from the method of the present invention, or the conventional sintered bodies 1, 2 produced by the conventional methods 1, 2 are electrically conductive, Any of thermal conductivity, heat resistance, hardness, and chemical stability is inferior to the sintered bodies 1 to 15 of the present invention.
As described above, according to the present invention, a diamond sintered body having good conductivity can be efficiently manufactured by a simple process, and the diamond sintered body obtained by the manufacturing method of the present invention Since it has conductivity sufficient for processing by processing, the application field of the diamond sintered body is expanded, and the practical effect is extremely large.
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| CN2007800385746A CN101528634B (en) | 2006-10-31 | 2007-10-26 | Diamond sinter with satisfactory electrical conductivity and process for producing the same |
| US12/446,353 US8043533B2 (en) | 2006-10-31 | 2007-10-26 | Diamond sintered compact having high electrical conductivity and production method thereof |
| EP07830622.2A EP2100863B1 (en) | 2006-10-31 | 2007-10-26 | Process for manufacturing a boron-doped diamond sinter with satisfactory electrical conductivity |
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| JP5263500B2 (en) * | 2008-07-22 | 2013-08-14 | 三菱マテリアル株式会社 | Multi-layered diamond-based sintered body, diamond tool, and method for producing the same |
| JP7188726B2 (en) * | 2017-06-28 | 2022-12-13 | トーメイダイヤ株式会社 | Diamond-based composite material using boron-based binder, method for producing the same, and tool element using the same |
| CN111356651A (en) | 2017-11-16 | 2020-06-30 | 株式会社大赛璐 | Electrode material for capacitor |
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