JPH0735304B2 - Method for manufacturing boron nitride sintered body - Google Patents
Method for manufacturing boron nitride sintered bodyInfo
- Publication number
- JPH0735304B2 JPH0735304B2 JP62259654A JP25965487A JPH0735304B2 JP H0735304 B2 JPH0735304 B2 JP H0735304B2 JP 62259654 A JP62259654 A JP 62259654A JP 25965487 A JP25965487 A JP 25965487A JP H0735304 B2 JPH0735304 B2 JP H0735304B2
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- Japan
- Prior art keywords
- boron nitride
- sintered body
- boron
- powder
- weight
- Prior art date
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Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は耐熱性、耐熱衝撃性、潤滑性、耐蝕性、電気絶
縁性、熱伝導性等にすぐれたセラミックス材料である高
純度六方晶窒化ホウ素（以後窒化ホウ素と称する）焼結
体の製造法に関する。DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a high-purity hexagonal nitriding which is a ceramic material excellent in heat resistance, thermal shock resistance, lubricity, corrosion resistance, electrical insulation, thermal conductivity and the like. The present invention relates to a method for manufacturing a boron (hereinafter referred to as boron nitride) sintered body.
窒化ホウ素は熱的、化学的、電気的特性に優れ、かつ潤
滑性を有し、機械加工が容易にできるなど多くのすぐれ
た性能を備えたセラミックス材料である。Boron nitride is a ceramic material having many excellent properties such as excellent thermal, chemical and electrical properties, lubricity, and ease of machining.
即ち、熱的には不活性雰囲気中では約3000℃まで安定で
ありかつ熱伝導率がきわめて高く熱衝撃抵抗が大きく、
また、溶融金属にぬれ難く、反応しないなど化学的な安
定性にも優れており、耐熱、耐蝕材料としての用途が非
常に広い。また熱的安定性に加えて潤滑性に優れている
ので、高温潤滑材として貴重な材料でもある。That is, it is thermally stable up to about 3000 ° C in an inert atmosphere, has extremely high thermal conductivity, and has high thermal shock resistance,
In addition, it has excellent chemical stability such that it is difficult to wet the molten metal and does not react, and its application as a heat resistant and corrosion resistant material is very wide. Further, it is excellent in lubricity in addition to thermal stability, so it is a valuable material as a high temperature lubricant.
更に電気抵抗が極めて大きく、高温になっても変化が小
さいことから広い温度範囲で使える電気絶縁材料でもあ
る。Furthermore, since it has an extremely high electric resistance and its change is small even at high temperatures, it is an electric insulating material that can be used in a wide temperature range.
ところが窒化ホウ素は優れた熱的、化学的特性を有する
反面、難焼結性であり、焼結体を製造するには高温及び
機械的高圧処理を必要としている。例えば工場規模で窒
化ホウ素焼結体を製造する場合には、窒化ホウ素製造時
に未反応B2O3を残した状態の窒化ホウ素原料をホットプ
レスにより加熱加圧したり、あるいは窒化ホウ素粉体に
アルカリ土類金属ホウ酸塩例えばMgO・B2O3、CaO・B
2O3、SrO・B2O3等をバインダーとして数％から10数％混
合し黒鉛ダイスに詰めて200から400kg/cm2で加圧しなが
ら高周波誘導加熱炉を用いて2000℃付近の温度で加熱さ
せる方法（特公昭49-40124号）が取られている。However, while boron nitride has excellent thermal and chemical properties, it is difficult to sinter, and high temperature and mechanical high pressure treatments are required to produce a sintered body. For example, when manufacturing a boron nitride sintered body on a factory scale, the boron nitride raw material in a state where unreacted B 2 O 3 remains during the production of boron nitride is heated and pressed by hot pressing, or boron nitride powder is treated with an alkali. Earth metal borates such as MgO ・ B 2 O 3 , CaO ・ B
2 O 3 , SrO / B 2 O 3 etc. are mixed as a binder in the range of several% to 10% and packed in a graphite die and pressurized at 200 to 400 kg / cm 2 while using a high frequency induction heating furnace at a temperature of around 2000 ° C. The method of heating (Japanese Patent Publication No. Sho 49-40124) is used.
又本願発明者はバインダーの少ない窒化ホウ素焼結体の
製造法を開発したが（特開昭59-162179）、この方法に
おいても焼結はホットプレスに限定されている。Further, the inventor of the present invention has developed a method for producing a boron nitride sintered body having a small amount of binder (Japanese Patent Laid-Open No. 59-162179), but in this method as well, sintering is limited to hot pressing.
前記の従来方法のうち未反応B2O3を残した状態の窒化ホ
ウ素をホットプレスの出発原料としたり、アルカリ土類
金属塩をバインダーとして多量混合する方法には次のよ
うな欠点がある。Among the above-mentioned conventional methods, the method in which boron nitride in a state where unreacted B 2 O 3 is left is used as a starting material for hot pressing or a large amount is mixed with an alkaline earth metal salt as a binder has the following drawbacks.
これらの従来法で得られた焼結体には数％から10数％の
B2O3を主体とした酸化物が混在することになり、窒化ホ
ウ素本来の優れた特徴が充分に発揮できない。特に、不
活性雰囲気中では約3000℃付近まで安定な窒化ホウ素も
B2O3を主体とする酸化物バインダーが混在した焼結体で
は千数百度よりバインダーが吹き出し、接触している別
の材料を反応したり、バインダーの揮散によって付近を
汚したり、又、窒化ホウ素焼結体自体に亀裂が生じるな
どの現象が生じるので使用温度が大幅に限定されている
のが現状である。Sintered bodies obtained by these conventional methods have several percent to ten percent
Since oxides mainly composed of B 2 O 3 are mixed, the original excellent characteristics of boron nitride cannot be fully exhibited. In particular, boron nitride that is stable up to about 3000 ° C in an inert atmosphere
In a sintered body mixed with an oxide binder mainly composed of B 2 O 3 , the binder blows out from a few thousand degrees to react with another material that is in contact with it, stain the neighborhood by volatilization of the binder, or nitride it. At present, the operating temperature is greatly limited because a phenomenon such as cracking occurs in the boron sintered body itself.
従って、B2O3を主体とする比較的低融点バインダーが含
有されることに起因する上記の欠点がない窒化ホウ素
が、しかも、常圧焼結法においても製造できればこれま
でにない高品質の焼結体が安価に得られる。Therefore, if boron nitride, which does not have the above-mentioned drawbacks due to the inclusion of a relatively low-melting-point binder mainly composed of B 2 O 3 , can be produced even by the atmospheric pressure sintering method, it has a high quality as never before. A sintered body can be obtained at low cost.
なお本発明者らによる前記の特開昭59-162179に開示の
方法はバインダーの含有量は少ないが、焼結はホットプ
レスに限られる。The method disclosed in the above-mentioned JP-A-59-162179 by the present inventors has a small binder content, but sintering is limited to hot pressing.
本件発明者はホットプレスは勿論のこと常圧でも容易に
高密度で高強度であり、かつ高純度の窒化ホウ素焼結体
を得る製造法を開発することを目的として研究を行な
い、先にアルカリ土類金属化合物と炭化ホウ素を配合し
て成形・焼結する方法を出願した（特開昭64-3074号公
報（特願昭62-156563号））。The present inventor conducted research for the purpose of developing a production method for obtaining a high-purity boron nitride sintered body that is easily high-density and high-strength not only under hot pressing but also under normal pressure. An application was made for a method of blending an earth metal compound and boron carbide and molding and sintering (JP-A-64-3074 (Japanese Patent Application No. 62-156563)).
しかし、本件発明者はさらに研究を進め、従来のバイン
ダーを用いる製造法に代って特定の窒化ホウ素粉末、す
なわち30m2/g以上のBET法比表面積を有する窒化ホウ素
粉末に炭化ホウ素粉末を配合して焼成すればアルカリ土
類金属化合物のような成分を添加することなく目的の焼
結体が得られることを発見して本発明を完成した。However, the present inventor further advanced the research, and instead of the conventional production method using a binder, a specific boron nitride powder, that is, a boron nitride powder having a BET method specific surface area of 30 m 2 / g or more was blended with the boron carbide powder. The present invention has been completed by discovering that the desired sintered body can be obtained without adding a component such as an alkaline earth metal compound by firing.
すなわち本件発明の要旨は30m2/g以上のBET法比表面積
を有する六方晶窒化ホウ素粉末60〜99.9重量％と炭化ホ
ウ素粉末0.1〜40重量％を配合して成形し、窒素又は窒
素を含有する非酸化性雰囲気中で炭化ホウ素を窒化ホウ
素に変換させる温度以上で焼成することを特徴とする窒
化ホウ素焼結体の製造法にある。That is, the gist of the present invention is to mix and mold 60 to 99.9% by weight of hexagonal boron nitride powder and 0.1 to 40% by weight of boron carbide powder having a BET specific surface area of 30 m 2 / g or more, and contain nitrogen or nitrogen. A method for producing a boron nitride sintered body is characterized by firing at a temperature not lower than a temperature at which boron carbide is converted to boron nitride in a non-oxidizing atmosphere.
以下に本発明について詳細に説明する。The present invention will be described in detail below.
窒化ホウ素粉体は一般にはホウ酸、無水酸化ホウ素又は
ホウ砂をアンモニアガス中で加熱するか或いはアンモニ
アガスを発生する含窒素有機化合物と混合して加熱し、
得られた窒化ホウ素を再度窒素雰囲気中で高温で加熱し
て結晶性を高め製品としている。このようにして得られ
た市販の窒化ホウ素は通常結晶サイズが１μが越える程
度である。Boron nitride powder is generally heated by heating boric acid, anhydrous boron oxide or borax in ammonia gas or by mixing with a nitrogen-containing organic compound that generates ammonia gas,
The obtained boron nitride is heated again in a nitrogen atmosphere at a high temperature to enhance the crystallinity and obtain a product. The commercially available boron nitride thus obtained usually has a crystal size of about 1 μm.
ここで、上記のような窒化ホウ素粉末に特定の物質を混
合し、再度加熱して結晶を成長させると非常に充填性が
高められ、このような粉末を原料として用いることは、
生成形体の密度を高め、ひいては焼結体密度を高める点
で有利である。Here, the boron nitride powder as described above is mixed with a specific substance, and when heated again to grow a crystal, the filling property is greatly improved. Using such a powder as a raw material,
It is advantageous in increasing the density of the green body, and thus in the density of the sintered body.
例えば市販の窒化ホウ素粉末に９重量％のホウ酸とCaO
換算で５重量％となるように炭酸カルシウムとフッ化カ
ルシウムを加え、ブリケットとなし窒素雰囲気中で2000
℃に加熱すれば結晶サイズは20〜40μとなる。For example, commercially available boron nitride powder with 9% by weight boric acid and CaO
Calcium carbonate and calcium fluoride were added so as to be 5% by weight, and 2000 in a briquette and nitrogen atmosphere.
When heated to ℃, the crystal size becomes 20-40μ.
但し、このようにして得られた粉末をそのまま又は粉砕
して用いると焼結体中に多量のアルカリ土類金属ホウ素
酸塩を残留させることになる。このことは、焼結体を千
数百度以上に加熱した場合に液相となって吹き出す場合
があるので、アルカリ土類金属ホウ素塩は除去したほう
が好ましい。窒化ホウ素粉末中のアルカリ土類金属ホウ
素塩は、例えば塩酸等の無機酸で処理すれば容易に除去
することができる。However, if the powder thus obtained is used as it is or after being pulverized, a large amount of alkaline earth metal borate will remain in the sintered body. This means that when the sintered body is heated to more than one thousand and several hundred degrees, it may be blown out in a liquid phase, so it is preferable to remove the alkaline earth metal boron salt. The alkaline earth metal boron salt in the boron nitride powder can be easily removed by treating with an inorganic acid such as hydrochloric acid.
本発明における出発原料粉末はどのような窒化ホウ素で
も構わないが、高密度で高強度の焼結体を得るためには
上記のように、窒化ホウ素粉末に種々処理を加えること
により、結晶性、純度を高めた粉末を用いることが好ま
しい。The starting material powder in the present invention may be any boron nitride, but in order to obtain a high-density and high-strength sintered body, as described above, by performing various treatments on the boron nitride powder, the crystallinity, It is preferable to use a powder with increased purity.
更に、市販の窒化ホウ素粉末や、前述のように特定の物
質とともに加熱処理して結晶性を高めた粉末は、一般に
は粗くそのまま用いるのは適当でない。そこでボールミ
ル等により微粉砕し、BET比表面積で30m2/g以上にする
必要があり好ましくは40m2/g以上で100m2/g以下である
その理由は、原料窒化ホウ素粉末のBET比表面積が30m2/
g未満の場合、得られる焼結体は高い密度を有するが、
強度が低く満足できる特性を備えていない。またBET比
表面積が30m2/g未満では焼成温度がはるかに高くとも焼
成中の炭化ホウ素から窒化ホウ素への変換が充分でな
く、焼結体内部に黒灰色部が認められ、密度、強度とも
に低い焼結体となる。一方原料窒化ホウ素粉末を余り細
かくすると例えばBET比表面積で100m2/g以上にした場合
生成形体密度が低下し、これを焼成しても高い密度の焼
結体は得られない。Further, commercially available boron nitride powder and powder obtained by heat treatment with a specific substance to enhance crystallinity as described above are generally coarse and not suitable for use as they are. Therefore, it is necessary to finely pulverize with a ball mill or the like and have a BET specific surface area of 30 m 2 / g or more and preferably 40 m 2 / g or more and 100 m 2 / g or less because the BET specific surface area of the raw material boron nitride powder is 30m 2 /
If less than g, the resulting sintered body has a high density,
It has low strength and does not have satisfactory characteristics. If the BET specific surface area is less than 30 m 2 / g, the conversion from boron carbide to boron nitride during firing is not sufficient even if the firing temperature is much higher, and a black gray portion is observed inside the sintered body, and both density and strength are It becomes a low sintered body. On the other hand, if the raw material boron nitride powder is made too fine, for example, when the BET specific surface area is 100 m 2 / g or more, the density of the green compact decreases, and even if this is sintered, a high density sintered body cannot be obtained.
次に焼結体製造方法について具体的に説明する。以上に
述べたような窒化ホウ素の微粉末は0.1〜40重量％の炭
化ホウ素とともにボールミル等を用いて湿式にて充分に
混合し乾燥して顆粒とする。常圧のもとで焼結させる場
合には配合原料を金型成形又はラバープレス或いはこれ
らの組み合わせにより所定形状で成形する。成形密度を
上げるには1000kg/cm2以上、好ましくは2000kg/cm2程度
で加圧成形する。Next, the method for producing a sintered body will be specifically described. The fine powder of boron nitride as described above is thoroughly mixed with 0.1 to 40% by weight of boron carbide by a wet process using a ball mill or the like and dried to give granules. In the case of sintering under normal pressure, the compounded raw material is molded into a predetermined shape by die molding, rubber pressing, or a combination thereof. To increase the molding density, pressure molding is performed at 1000 kg / cm 2 or more, preferably about 2000 kg / cm 2 .
勿論生成形体の密度が充分にあげられるならば加圧成形
方法に限定されることなくスリップキャスト法、押し出
し法等いずれの方法によっても構わない。Of course, the method is not limited to the pressure molding method as long as the density of the green body can be sufficiently increased, and any method such as a slip casting method and an extrusion method may be used.
得られた生成形体は黒く、これを窒素又は窒素を含有す
る非酸化性雰囲気中で20〜200℃/minの昇温速度で1700
℃以上に昇温し、２〜10時間焼成して炭化ホウ素を雰囲
気中の窒素と反応させて窒化ホウ素とすることにより白
い焼結体となる。The obtained green form is black, and it is 1700 at a heating rate of 20 to 200 ° C / min in nitrogen or a non-oxidizing atmosphere containing nitrogen.
A white sintered body is obtained by heating the temperature to ℃ or more and firing for 2 to 10 hours to react boron carbide with nitrogen in the atmosphere to form boron nitride.
ホットプレス法で焼結させる場合は配合原料を黒鉛ダイ
スに詰めて200〜400kg/cm2で加圧しながら高周波誘導加
熱炉等を用いて窒素雰囲気中で1800℃以上に加熱して焼
成すると黒鉛ダイスは通気性があるので前記と同様に反
応して白い焼結体が得られる。When sintering by hot press method, the compounding raw material is packed in a graphite die and pressed at 200 to 400 kg / cm 2 and heated to 1800 ° C or higher in a nitrogen atmosphere using a high frequency induction heating furnace etc. Has a gas permeability, and reacts in the same manner as described above to obtain a white sintered body.
ここで炭化ホウ素の作用について説明する。炭化ホウ素
はその粒径が30μ以下好ましくは10μ以下であるものを
選ぶ。炭化ホウ素の配合量を0.1〜40重量％に限定した
のは、炭化ホウ素を配合しない場合は密度・強度ともに
低い焼結体しか得られず、40重量％をこえる場合には生
成形体密度が低下し、これを焼成しても密度の高い焼結
体とならないからである。Here, the action of boron carbide will be described. Boron carbide having a particle size of 30 μm or less, preferably 10 μm or less is selected. The content of boron carbide is limited to 0.1-40% by weight, unless boron carbide is added, only a sintered body with low density and strength can be obtained, and if it exceeds 40% by weight, the density of the green compact decreases. However, even if it is fired, it does not become a sintered body having a high density.
前にも述べたように炭化ホウ素は焼成中に雰囲気の窒素
と反応して窒化ホウ素に変化する。この場合、炭化ホウ
素粉末が粗いと炭化ホウ素と窒素が完全には反応せず、
焼結体内部に炭化ホウ素を残留させる。従って、炭化ホ
ウ素を窒化ホウ素へ完全に変換させるにはまず炭化ホウ
素粉末が細かいこと、具体的には30μ以下であることが
好ましい。このほかに炭化ホウ素を完全に窒化ホウ素へ
変換させるには、原料窒化ホウ素粉末が細かく具体的に
は前記したようにBET比表面積で30m2/gであることが必
要である。ここで、アルカリ土類金属化合物を添加する
と炭化ホウ素は容易に窒化ホウ素へ変換するが、高純度
焼結体を得る目的には合わない。As described above, boron carbide reacts with nitrogen in the atmosphere during firing and changes into boron nitride. In this case, if the boron carbide powder is coarse, the boron carbide and nitrogen will not completely react,
Boron carbide is left inside the sintered body. Therefore, in order to completely convert boron carbide into boron nitride, it is preferable that the boron carbide powder is fine, specifically 30 μm or less. In addition, in order to completely convert boron carbide into boron nitride, the raw material boron nitride powder needs to be fine, specifically, the BET specific surface area of 30 m 2 / g as described above. Here, when an alkaline earth metal compound is added, boron carbide is easily converted into boron nitride, but this is not suitable for the purpose of obtaining a high-purity sintered body.
焼成温度は、焼結体密度・強度を満足できる程度にまで
上げるだけならば1700℃以上あればよい。但し1700℃に
近い温度で焼成して得られた焼結体は配合した炭化ホウ
素及び又は成形用有機質バインダーに起因する黒色部又
は灰色部が特に焼結体内部に認められる。焼結体の内部
まで完全に白色化する為には、1800℃以上に加熱するこ
とが好ましく、又、炭化ホウ素配合量が特に多い場合又
は成形体が大きい場合には1900℃以上に加熱することが
好ましい。以上の点に留意して配合した炭化ホウ素を焼
成中に完全に窒化ホウ素へ変化させてはじめて目的とす
る高純度、高密度、かつ高強度の焼結体が得られる。The firing temperature may be 1700 ° C. or higher if only raising the density and strength of the sintered body to an extent that can be satisfied. However, in the sintered body obtained by firing at a temperature close to 1700 ° C., a black portion or a gray portion due to the blended boron carbide and / or the organic binder for molding is particularly found inside the sintered body. In order to completely whiten the inside of the sintered body, it is preferable to heat it to 1800 ° C or higher, and if the content of boron carbide is particularly large or the molded body is large, heat it to 1900 ° C or higher. Is preferred. The desired high-purity, high-density, and high-strength sintered body can be obtained only by completely converting the blended boron carbide into boron nitride during firing.
このようにして得られた焼結体中の炭素含有量は0.1重
量％以下であり極めて少ない。The carbon content in the thus obtained sintered body is 0.1% by weight or less, which is extremely low.
以下実施例、比較例により本発明を説明する。The present invention will be described below with reference to Examples and Comparative Examples.
〔実施例１〕 BET比表面積が5.5m2/gである市販の高純度窒化ホウ素粉
末をアルミナ製ポットミルを用いて粉砕しBET比表面積
が42m2/gの粉末を得た。これの85重量％に平均粒子径が
約１μの炭化ホウ素を15重量％加えてこれらを水及び有
機質バインダーとともにアルミナ製ポットミルを用いて
20時間混合した。Example 1 A commercially available high-purity boron nitride powder having a BET specific surface area of 5.5 m 2 / g was pulverized using an alumina pot mill to obtain a powder having a BET specific surface area of 42 m 2 / g. To 85% by weight of this, 15% by weight of boron carbide having an average particle size of about 1μ was added, and these were mixed with water and an organic binder using an alumina pot mill.
Mix for 20 hours.
噴霧乾燥により顆粒とした後、金型で2000kg/cm2の圧力
をかけて成形した。得られた生成形体の密度は1.87g/cm
3であった。この生成形体を電気加熱式密閉炉に挿入し
常圧を保持しつつ窒素ガスを流しながら１時間に50℃の
速度で1800℃まで昇温し２時間保持したのち炉内で冷却
し取り出した。得られた焼結体の密度は1.70g/cm3であ
った。又、焼結体より切り出した試験片（３×４×35m
m）の３点曲げ強度は412kg/cm2であった。After granulating by spray drying, it was molded by applying a pressure of 2000 kg / cm 2 with a mold. The density of the obtained green form is 1.87 g / cm.
Was 3 . This green body was inserted into an electrically heated closed furnace, and while maintaining a normal pressure and flowing nitrogen gas, the temperature was raised to 1800 ° C. at a rate of 50 ° C. for 1 hour and kept for 2 hours, then cooled in the furnace and taken out. The density of the obtained sintered body was 1.70 g / cm 3 . Also, test pieces cut out from the sintered body (3 x 4 x 35 m
The 3-point bending strength of m) was 412 kg / cm 2 .
焼結体中のB2O3含有量は0.08重量％炭素含有量は0.06重
量％であった。The B 2 O 3 content in the sintered body was 0.08% by weight, and the carbon content was 0.06% by weight.
〔実施例２〕 市販の窒化ホウ素粉末にCaO換算で５重量％となるよう
に酸化カルシウムとフッ化カルシウムを加え、更にB2O3
換算で５重量％となるようにホウ酸を加え、混合しブリ
ケットと成したのち、黒鉛るつぼに入れ高周波誘導加熱
炉を用いて窒素ガス中で2000℃で２時間焼成した。冷却
後炉内より取り出しアルミナ製ボールミルで粉砕し40メ
ッシュの篩で篩分けた。得られた窒化ホウ素1kgを12N塩
酸200ccと水20lとともにポリエチレン製容器に入れ、50
℃に加温しながら５時間攪拌した。次いで水を用いて洗
浄を繰り返し、洗浄水のpHが7.0となった時点でろ過し
乾燥した。得られた粉体はB2O3含有量が0.36重量％であ
り酸化カルシウム含有量が0.03重量％であった。Example 2 Calcium oxide and calcium fluoride were added to a commercially available boron nitride powder so as to be 5% by weight in terms of CaO, and further B 2 O 3 was added.
Boric acid was added so as to be 5% by weight, mixed and formed into a briquette, which was then placed in a graphite crucible and baked in a nitrogen gas at 2000 ° C. for 2 hours using a high frequency induction heating furnace. After cooling, it was taken out of the furnace, pulverized with an alumina ball mill, and sieved with a 40-mesh sieve. 1 kg of the obtained boron nitride was put in a polyethylene container together with 200 cc of 12N hydrochloric acid and 20 liters of water.
The mixture was stirred for 5 hours while warming to ℃. Then, washing with water was repeated, and when the washing water reached pH 7.0, it was filtered and dried. The obtained powder had a B 2 O 3 content of 0.36% by weight and a calcium oxide content of 0.03% by weight.
このようにして得た高結晶性、高純度窒化ホウ素粉末を
ボールミルを用いて粉砕しBET比表面積を47m2/gとし
た。これの90重量％に平均粒子径が約１μの炭化ホウ素
を10重量％加えてこれらを水及び有機質バインダーとと
もにアルミナ製ポットミルを用いて20時間混合した以後
は実施例１と同様にして焼結体を作製した。The highly crystalline and highly pure boron nitride powder thus obtained was crushed using a ball mill to have a BET specific surface area of 47 m 2 / g. To 90% by weight of this, 10% by weight of boron carbide having an average particle diameter of about 1 μm was added, and these were mixed with water and an organic binder for 20 hours using an alumina pot mill. Thereafter, a sintered body was prepared in the same manner as in Example 1. Was produced.
ここで得られた生成形体の密度は1.97であった。又焼結
体の密度は1.78m2/gであり、３点曲げ強度は587kg/cm2
であった焼結体中のB2O3含有量は0.11重量％炭素含有量
は0.07重量％であった。The density of the green form obtained here was 1.97. The density of the sintered body is 1.78 m 2 / g and the three-point bending strength is 587 kg / cm 2
The B 2 O 3 content in the sintered body was 0.11% by weight and the carbon content was 0.07% by weight.
〔比較例１〕 炭化ホウ素を配合しないほかは実施例１と同様にして作
製した焼結体の密度は1.61g/cm3であり３点曲げ強度は1
82kg/cm2であった。[Comparative Example 1] A sintered body produced in the same manner as in Example 1 except that boron carbide was not added had a density of 1.61 g / cm 3 and a three-point bending strength of 1
It was 82 kg / cm 2 .
〔比較例２〕 BET比表面積が15m2/gの窒化ホウ素に平均粒子径が約１
μの炭化ホウ素を15重量％加えて以後実施例１と同様に
して焼結体を作製した。ここで得られた焼結体の密度は
1.68g/cm3であり曲げ強度は172kg/cm2であった。また17
00℃で２時間焼成した焼結体は内部に黒灰色部が認めら
れ、Ｘ線回析による分析で微量の炭化ホウ素が析出さ
れ、焼成中の炭化ホウ素から窒化ホウ素への変換が充分
でなかった。Comparative Example 2 Boron nitride having a BET specific surface area of 15 m 2 / g and an average particle size of about 1
After adding 15% by weight of boron carbide of μ, a sintered body was manufactured in the same manner as in Example 1. The density of the sintered body obtained here is
The bending strength was 1.68 g / cm 3 and the bending strength was 172 kg / cm 2 . Again 17
A black gray portion was observed inside the sintered body that was fired at 00 ° C for 2 hours, and a trace amount of boron carbide was deposited by analysis by X-ray diffraction, and the conversion of boron carbide to boron nitride during firing was insufficient. It was
以上の実施例から分るようにBET比表面積で30m2/gの窒
化ホウ素粉末に炭化ホウ素を配合すれば常圧のもとでも
緻密に焼結し、その焼結体は従来のホットプレス窒化ホ
ウ素に匹敵する強度を有している。更にこの焼結体は純
度が高く不活性雰囲気中で1800℃に加熱しても全く変化
がなく熱的に安定である。As can be seen from the above examples, if boron carbide powder is added to boron nitride powder having a BET specific surface area of 30 m 2 / g, it will sinter densely under normal pressure, and the sintered body will have a conventional hot press nitriding property. It has a strength comparable to that of boron. Further, this sintered body has a high purity and is thermally stable with no change even when heated to 1800 ° C. in an inert atmosphere.
このように本発明によれば安価で高品位窒化ホウ素焼結
体が得られるので、この焼結体は今後耐熱性、耐熱衝撃
性、潤滑性、耐蝕性、電気絶縁性、熱伝導性が要求され
る分野で活用されることが期待できる。As described above, according to the present invention, a high-quality boron nitride sintered body can be obtained at a low cost, and thus this sintered body is required to have heat resistance, thermal shock resistance, lubricity, corrosion resistance, electrical insulation, and thermal conductivity in the future. It can be expected to be utilized in the fields where it is used.
Claims (1)
晶窒化ホウ素粉末60〜99.9重量％と炭化ホウ素粉末0.1
〜40重量％を配合して成形し、窒素又は窒素を含有する
非酸化性雰囲気中で炭化ホウ素を窒化ホウ素に変換させ
る温度以上で焼成することを特徴とする窒化ホウ素焼結
体の製造法。1. A hexagonal boron nitride powder having a BET specific surface area of 30 m 2 / g or more of 60 to 99.9% by weight and a boron carbide powder of 0.1.
A method for producing a boron nitride sinter, which comprises blending up to 40% by weight and molding, and firing in a non-oxidizing atmosphere containing nitrogen or at a temperature not lower than a temperature at which boron carbide is converted to boron nitride.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62259654A JPH0735304B2 (en) | 1987-10-16 | 1987-10-16 | Method for manufacturing boron nitride sintered body |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62259654A JPH0735304B2 (en) | 1987-10-16 | 1987-10-16 | Method for manufacturing boron nitride sintered body |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01103960A JPH01103960A (en) | 1989-04-21 |
| JPH0735304B2 true JPH0735304B2 (en) | 1995-04-19 |
Family
ID=17337053
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62259654A Expired - Lifetime JPH0735304B2 (en) | 1987-10-16 | 1987-10-16 | Method for manufacturing boron nitride sintered body |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0735304B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3723489A (en) * | 1971-02-25 | 1973-03-27 | Ciba Geigy Corp | Metal derivatives of 3,5-di-t-butyl-4-hydroxyphenyl propionic acid |
| JP2531871B2 (en) * | 1991-06-18 | 1996-09-04 | 昭和電工株式会社 | Method for manufacturing high-density boron nitride pressureless sintered body |
| JP4542747B2 (en) * | 2003-02-19 | 2010-09-15 | 国立大学法人東京工業大学 | Manufacturing method of high strength hexagonal boron nitride sintered body |
| JP5969314B2 (en) * | 2012-08-22 | 2016-08-17 | デンカ株式会社 | Boron nitride powder and its use |
| WO2014136959A1 (en) * | 2013-03-07 | 2014-09-12 | 電気化学工業株式会社 | Boron-nitride powder and resin composition containing same |
-
1987
- 1987-10-16 JP JP62259654A patent/JPH0735304B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01103960A (en) | 1989-04-21 |
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