JPH05330917A - Production of highly heat conductive silicon carbide sintered compact - Google Patents
Production of highly heat conductive silicon carbide sintered compactInfo
- Publication number
- JPH05330917A JPH05330917A JP4136973A JP13697392A JPH05330917A JP H05330917 A JPH05330917 A JP H05330917A JP 4136973 A JP4136973 A JP 4136973A JP 13697392 A JP13697392 A JP 13697392A JP H05330917 A JPH05330917 A JP H05330917A
- Authority
- JP
- Japan
- Prior art keywords
- silicon carbide
- sintered body
- sintered compact
- thermal conductivity
- carbon
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、高熱伝導性に優れ、高
熱伝導性基板、ヒートシンク、熱交換器等に適用される
炭化珪素質焼結体の製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a silicon carbide sintered body which is excellent in high heat conductivity and is applied to a high heat conductivity substrate, a heat sink, a heat exchanger and the like.
【０００２】[0002]
【従来技術】従来から、炭化珪素質焼結体は機械的特性
に優れ、特に高温において強度劣化の小さい材料として
注目され、各種の分野への応用が進められている。この
ような炭化珪素質焼結体は、一般に炭化珪素粉末に対し
て炭素および硼素を焼結助剤として添加し、これを成形
後、Ａｒ等の不活性雰囲気中で無加圧で２０００〜２２
００℃で焼成することにより得られている。このように
して得られる炭化珪素質焼結体の熱伝導率は、せいぜい
６０〜８０Ｗ／ｍ・ｋ程度である。2. Description of the Related Art Conventionally, a silicon carbide-based sintered body has been attracting attention as a material having excellent mechanical properties and having little strength deterioration particularly at high temperatures, and its application to various fields has been promoted. In such a silicon carbide-based sintered body, carbon and boron are generally added to silicon carbide powder as a sintering aid, and after molding, 2000 to 22 without pressure in an inert atmosphere such as Ar.
It is obtained by firing at 00 ° C. The thermal conductivity of the silicon carbide based sintered body thus obtained is at most about 60 to 80 W / m · k.
【０００３】これに対して、炭化珪素質焼結体を高熱伝
導化する技術として、炭化珪素に対して焼結助剤として
ＢｅＯを添加してホットプレス焼成することが行われ、
これによれば、２７０Ｗ／ｍ・ｋレベルの高い熱伝導率
が得られ、各種の基板やヒートシンク材料として採用さ
れている。また、特開平４−１３００６１号公報によれ
ば気相法により作成した炭化珪素超微粒粉末を用いた助
剤無添加焼結により高熱伝導が得られるとされる。On the other hand, as a technique for increasing the thermal conductivity of a silicon carbide based sintered body, BeO is added to silicon carbide as a sintering aid to perform hot press firing.
According to this, a high thermal conductivity of 270 W / m · k level is obtained, and it is used as various substrates and heat sink materials. Further, according to Japanese Patent Laid-Open No. 4-130061, it is said that high thermal conductivity can be obtained by additive-free sintering using ultrafine silicon carbide powder prepared by a vapor phase method.
【０００４】[0004]
【発明が解決しようとする問題点】しかしながら、Ｂｅ
Ｏ添加系の炭化珪素質焼結体は、ＢｅＯ自体が毒性を有
することから人体に及ぼす影響が大きく製造時の厳しい
安全管理が必要となり、しかも焼結性が劣るので製法が
ホットプレス法に限られるために焼結体の形状が制限さ
れ生産性において問題があった。また、炭化珪素超微粉
は高価であり、かつ取扱も容易ではなく、助剤を添加し
ないと焼結性が低いので焼成管理が難しくなる。したが
って、従来原料を用いた雰囲気焼成が望まれてきた。[Problems to be Solved by the Invention] However, Be
The O-containing silicon carbide sintered body has a large effect on the human body because BeO itself has toxicity and requires strict safety control during production. Moreover, since the sinterability is poor, the manufacturing method is limited to the hot pressing method. Therefore, the shape of the sintered body is limited and there is a problem in productivity. Further, ultrafine silicon carbide powder is expensive and not easy to handle, and if an auxiliary agent is not added, sinterability is low, and therefore firing control becomes difficult. Therefore, it has been desired to perform atmospheric firing using conventional raw materials.
【０００５】[0005]
【問題を解決するための手段】本発明者等は、上記の問
題点に対して、ＢｅＯや超微粉による無助剤法等を用い
ることなく、炭化珪素質焼結体の熱伝導率を高める方法
について鋭意検討した結果、炭素および硼素を焼結助剤
として添加した常法により焼結した焼結体に対して、高
圧雰囲気中で熱処理を行うことにより、従来の炭素と硼
素を添加した炭化珪素質焼結体に比較して大幅に熱伝導
率を向上できることを知見した。Means for Solving the Problems In order to solve the above problems, the present inventors have improved the thermal conductivity of a silicon carbide sintered body without using a non-auxiliary method using BeO or ultrafine powder. As a result of diligent study on the method, it was found that a conventional sintered body containing carbon and boron as a sintering aid was heat treated in a high-pressure atmosphere to obtain a carbonized body containing conventional carbon and boron. It was found that the thermal conductivity can be significantly improved as compared with the silicon-based sintered body.
【０００６】即ち、本発明の炭化珪素質焼結体の製法に
よれば、炭化珪素を主成分とし、焼結助剤として少なく
とも炭素および硼素を含有する成形体を真空中、又は不
活性雰囲気中で焼成して相対密度９４％以上の焼結体を
得、これを不活性ガス圧力１０００気圧以上、１７００
℃以上の高温高圧中で熱処理を行うことにより１００Ｗ
／ｍ・ｋ以上の熱伝導率を有する炭化珪素質焼結体を得
ることを特徴とするものである。That is, according to the method for producing a silicon carbide-based sintered body of the present invention, a molded body containing silicon carbide as a main component and at least carbon and boron as a sintering aid is vacuumed or in an inert atmosphere. To obtain a sintered body having a relative density of 94% or more, and the inert gas pressure of 1000 atm or more, 1700
100W by heat treatment in high temperature and high temperature above ℃
It is characterized in that a silicon carbide based sintered body having a thermal conductivity of / m · k or more is obtained.
【０００７】以下、本発明を詳述する。本発明の製法に
よれば、まず出発原料として炭化珪素粉末、および焼結
助剤として炭素および硼素を含有する各種の化合物を用
意する。炭化珪素粉末としてはα型、β型のいずれか、
あるいはこれらを混合して使用することができ、平均粒
径は０．１〜１μｍが適当である。また、熱処理前の焼
結体中の炭化珪素がα型、β型、あるいはその混合体の
いずれでもよい。また、焼結助剤としては、炭素成分と
して、カーボンブラック、グラファイト等の他に熱分解
により炭素を生成しうるフェノール樹脂やコールタール
ピッチ等を用いることができる。また、硼素成分として
は、Ｂ4 Ｃや金属硼素等が挙げられる。これら焼結助剤
は、最終的に炭化珪素１００重量部に対して、炭素が１
〜４重量部、硼素が０．１５〜０．４重量部となる量を
添加することが望ましい。The present invention will be described in detail below. According to the manufacturing method of the present invention, first, various compounds containing silicon carbide powder as a starting material and carbon and boron as a sintering aid are prepared. As the silicon carbide powder, either α type or β type,
Alternatively, these may be used as a mixture, and the average particle diameter is suitably 0.1 to 1 μm. Further, the silicon carbide in the sintered body before heat treatment may be α-type, β-type, or a mixture thereof. Further, as the sintering aid, in addition to carbon black, graphite and the like as the carbon component, phenol resin or coal tar pitch which can generate carbon by thermal decomposition can be used. In addition, examples of the boron component include B 4 C and metallic boron. These sintering aids finally contain 1 part of carbon based on 100 parts by weight of silicon carbide.
It is desirable to add -4 parts by weight and boron in an amount of 0.15-0.4 parts by weight.
【０００８】次に、これらの原料粉末を所定の割合で秤
量し、ボールミル等の混合手段により充分に混合した
後、この粉末にバインダーを添加し、周知の成形方法、
例えば、プレス成形、押出成形、鋳込み成形、冷間静水
圧成形等により所望の形状に成形する。なお、焼結助剤
としてフェノール樹脂等を添加した場合には、６００〜
８００℃で成形体を非酸化性雰囲気中で仮焼処理して熱
分解することにより炭素を生成することができる。Next, these raw material powders are weighed at a predetermined ratio and thoroughly mixed by a mixing means such as a ball mill, and then a binder is added to this powder to carry out a well-known molding method,
For example, it is formed into a desired shape by press molding, extrusion molding, cast molding, cold isostatic molding, or the like. In addition, when phenol resin etc. are added as a sintering aid, 600-
Carbon can be generated by calcining the molded body at 800 ° C. in a non-oxidizing atmosphere and thermally decomposing it.
【０００９】次に、上記のようにして得られた成形体を
真空中、あるいはＡｒ等の不活性雰囲気中で１７００〜
２１００℃の温度で焼成する。この時の焼成手段として
は、無加圧焼成法、ホットプレス法等が上げられる。ま
た、プラズマ焼成法等の手段を用いてもよい。本発明に
よれば、この焼成工程により得られる焼結体の密度を９
４％以上、特に９５〜９７％に制御する。Next, the molded body obtained as described above is heated to 1700 in vacuum or in an inert atmosphere such as Ar.
Baking at a temperature of 2100 ° C. As a firing means at this time, a pressureless firing method, a hot pressing method, or the like can be used. Alternatively, a means such as a plasma firing method may be used. According to the present invention, the density of the sintered body obtained by this firing step is 9
It is controlled to 4% or more, particularly 95 to 97%.
【００１０】このようにして得られた炭化珪素質焼結体
の熱伝導率はせいぜい約６０〜８０Ｗ／ｍ・ｋ程度であ
るが、本発明によれば、この低熱伝導率の炭化珪素質焼
結体をアルゴンガスなどの不活性ガス圧力が１０００気
圧以上、特に１５００気圧以上、熱処理温度１７００℃
以上、特に１９００℃〜２１００℃の温度でおよそ１／
４〜３時間程度熱処理を行う。この熱処理によって焼結
体の熱伝導を著しく向上させることができる。なお、こ
の熱処理時の雰囲気が窒素であると、焼結体の表面の炭
化珪素が窒化されて窒化珪素と炭素が生成されてしま
う。The silicon carbide-based sintered body thus obtained has a thermal conductivity of about 60 to 80 W / m · k at most, but according to the present invention, this low-thermal-conductivity silicon carbide-based sintered body is used. The pressure of the inert gas such as argon gas is 1000 atm or more, especially 1500 atm or more, and the heat treatment temperature is 1700 ° C
Above about 1 / about 2900 ℃
Heat treatment is performed for about 4 to 3 hours. This heat treatment can remarkably improve the thermal conductivity of the sintered body. If the atmosphere during this heat treatment is nitrogen, silicon carbide on the surface of the sintered body will be nitrided to generate silicon nitride and carbon.
【００１１】[0011]
【作用】本発明によれば、焼結助剤として炭素および硼
素を用いて固相焼結した炭化珪素質焼結体を所定の高圧
不活性ガス中で熱処理することにより、焼結体の熱伝導
率を顕著に高めることができる。According to the present invention, the heat treatment of the sintered body is carried out by heat-treating the silicon carbide sintered body which is solid-phase sintered using carbon and boron as the sintering aid in a predetermined high pressure inert gas. The conductivity can be significantly increased.
【００１２】この高熱伝導化の機構は明確ではないが、
焼結工程により焼結体密度を前述した所定値以上とし、
アルゴン等の不活性気体や窒素の高圧ガス中で高温処理
をすることによって、炭化珪素結晶に存在する結晶欠陥
や結晶の歪みを解消し、炭化珪素結晶の完全化が進み、
フォノンの散乱を小さくすることができ、結果として高
熱伝導が得られるものと考えられる。Although the mechanism of this high thermal conductivity is not clear,
By the sintering step, the density of the sintered body is equal to or higher than the predetermined value described above,
By performing high-temperature treatment in an inert gas such as argon or a high-pressure gas such as nitrogen, crystal defects and crystal strain existing in the silicon carbide crystal are eliminated, and the silicon carbide crystal is completed,
It is considered that phonon scattering can be reduced, resulting in high heat conduction.
【００１３】なお、本発明において、焼成終了後の焼結
体の相対密度を９４％以上に限定したのは、相対密度が
９４％よりも低いと、高圧高温処理による結晶の完全化
が十分進行せず、熱伝導率の向上効果が小さいためであ
る。In the present invention, the relative density of the sintered body after firing is limited to 94% or more. When the relative density is lower than 94%, the completion of the crystal by the high pressure and high temperature treatment is sufficiently advanced. This is because the effect of improving the thermal conductivity is small.
【００１４】本発明によれば、これまでＢｅＯ等の毒性
の物質を全く用いることなく、従来６０〜８０Ｗ／ｍ・
ｋ程度の熱伝導率から、１００Ｗ／ｍ・ｋ以上、特に後
述する実施例によれば、１５０Ｗ／ｍ・ｋの熱伝導率を
有する炭化珪素質焼結体を得ることができる。According to the present invention, the conventional 60 to 80 W / m.multidot.
From a thermal conductivity of about k, it is possible to obtain a silicon carbide based sintered body having a thermal conductivity of 100 W / m · k or more, and particularly according to an example described later.
【００１５】以下、本発明を次の例で説明する。The present invention will be described below with reference to the following examples.
【００１６】[0016]
実施例１ 平均粒径が０．４μｍのα型炭化珪素粉末１００重量部
に対してＢ4 Ｃを０．３重量部添加し充分に混合した
後、炭化率４０％のフェノール樹脂を用いて炭素換算量
が２重量部となるように添加した。Example 1 0.3 part by weight of B 4 C was added to 100 parts by weight of α-type silicon carbide powder having an average particle size of 0.4 μm and mixed well, and then carbon was obtained by using a phenol resin having a carbonization rate of 40%. It was added so that the converted amount would be 2 parts by weight.
【００１７】この混合粉末を用いて、成形圧力１０００
ｋｇ／ｃｍ2 で外径６０ｍｍ、厚み１０ｍｍの形状に金
型成形し、生密度２．１ｇ／ｃｃの生成形体を得た。次
に、この成形体をアルゴン雰囲気中、１９５０〜２１０
０℃で焼成して相対密度９４〜９８％の焼結体を得た。
これらを表１に示す窒素およびアルゴンの高圧ガス中で
熱処理を行い、試料を得た。また、比較のために熱処理
をおこなっていない通常の焼結体（相対密度９８．１
％）の測定結果も示した。A molding pressure of 1000 is obtained by using this mixed powder.
Molded into a shape having an outer diameter of 60 mm and a thickness of 10 mm at kg / cm 2 to obtain a green molded body having a green density of 2.1 g / cc. Next, this molded body is subjected to 1950 to 210 in an argon atmosphere.
It was fired at 0 ° C. to obtain a sintered body having a relative density of 94 to 98%.
These were heat-treated in a high pressure gas of nitrogen and argon shown in Table 1 to obtain samples. For comparison, a normal sintered body not subjected to heat treatment (relative density 98.1
%) Measurement results are also shown.
【００１８】上記工程において、熱処理前後の焼結体の
密度をアルキメデス法により測定した。また、熱処理後
の焼結体の熱伝導率を厚さ２．５〜３．０ｍｍの試料に
対して室温にてレーザーフラッシュ法により測定した。In the above process, the density of the sintered body before and after the heat treatment was measured by the Archimedes method. Further, the thermal conductivity of the sintered body after heat treatment was measured by a laser flash method at room temperature for a sample having a thickness of 2.5 to 3.0 mm.
【００１９】[0019]
【表１】 [Table 1]
【００２０】表１によれば、熱処理を施さない従来の高
密度の炭化珪素質焼結体（試料Ｎo.１２）は、熱伝導率
は６７Ｗ／ｍ・ｋと低い。また、熱処理前の相対密度が
９４％より小さい試料Ｎo,１では、熱処理後の熱伝導率
の向上効果は小さい。これに対して、本発明に基づき、
熱処理前の焼結体の相対密度が９４％以上である場合に
は、いずれも１００Ｗ／ｍ・ｋ以上が達成され、特に相
対密度９５〜９７％では１３０Ｗ／ｍ・ｋ以上が達成さ
れた。According to Table 1, the conventional high-density silicon carbide-based sintered body (Sample No. 12) which is not heat-treated has a low thermal conductivity of 67 W / m · k. Further, in the sample No. 1, in which the relative density before heat treatment is smaller than 94%, the effect of improving the thermal conductivity after heat treatment is small. On the other hand, according to the present invention,
When the relative density of the sintered body before heat treatment was 94% or more, 100 W / m · k or more was achieved in all cases, and particularly 130 W / m · k or more was achieved at 95-97% relative density.
【００２１】実施例２ 実施例１と同様に、β型炭化珪素１００重量部に対し
て、炭素分２．５重量部、硼素分０．４重量部となるよ
うにＢ4 Ｃ、およびフェノール樹脂を添加した成形体を
２０００℃で２０分間焼成し、相対密度９４．５％の炭
化珪素質焼結体を得た。その後、窒素中で実施例１と同
様の高温高圧処理を行って、相対密度９８．１％の焼結
体を得た。この焼結体の熱伝導率は１６７Ｗ／ｍ・Ｋと
高いものであった。Example 2 Similar to Example 1, B 4 C and a phenol resin were added so that the carbon content was 2.5 parts by weight and the boron content was 0.4 parts by weight with respect to 100 parts by weight of β-type silicon carbide. The molded body added with was baked at 2000 ° C. for 20 minutes to obtain a silicon carbide-based sintered body having a relative density of 94.5%. Then, the same high temperature and high pressure treatment as in Example 1 was performed in nitrogen to obtain a sintered body having a relative density of 98.1%. The thermal conductivity of this sintered body was as high as 167 W / m · K.
【００２２】[0022]
【発明の効果】以上詳述した通り、本発明によれば、炭
化珪素質焼結体の高温における優れた機械的特性を維持
しつつ、しかも、ＢｅＯ等の毒性物質を用いることな
く、熱伝導率を高めることができる。また、この製法に
よれば、ホットプレス法を用いることがないためにあら
ゆる製品形状に適用することができる。As described in detail above, according to the present invention, the thermal conductivity of the silicon carbide based sintered material can be maintained while maintaining the excellent mechanical properties at high temperature without using a toxic substance such as BeO. The rate can be increased. Further, according to this manufacturing method, since the hot pressing method is not used, it can be applied to any product shape.
【００２３】これにより、炭化珪素質焼結体の半導体部
品用の放熱基板、ヒートシンク用材料や、熱交換器用構
造材料、摺動部材等への用途を拡大することができる。As a result, the use of the silicon carbide sintered body as a heat dissipation substrate for semiconductor parts, a heat sink material, a heat exchanger structural material, a sliding member, etc. can be expanded.
Claims (1)
なくとも炭素および硼素を含有する成形体を真空中、又
は不活性雰囲気中で焼成し、相対密度９４％以上の焼結
体を作成した後、該焼結体を不活性ガス圧力１０００気
圧以上、１７００℃以上の高温高圧中で熱処理を行なう
ことを特徴とする１００Ｗ／ｍ・ｋ以上の熱伝導率を有
する高熱伝導性炭化珪素焼結体の製造方法。1. A sintered body having a relative density of 94% or more is produced by firing a compact containing silicon carbide as a main component and at least carbon and boron as a sintering aid in a vacuum or in an inert atmosphere. After that, the sintered body is subjected to a heat treatment at a high temperature and high pressure of at least 1000 atm of inert gas pressure and at least 1700 ° C., which is characterized by high thermal conductivity silicon carbide firing having a thermal conductivity of 100 W / m · k or more. A method for producing a bound body.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4136973A JPH05330917A (en) | 1992-05-28 | 1992-05-28 | Production of highly heat conductive silicon carbide sintered compact |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4136973A JPH05330917A (en) | 1992-05-28 | 1992-05-28 | Production of highly heat conductive silicon carbide sintered compact |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05330917A true JPH05330917A (en) | 1993-12-14 |
Family
ID=15187804
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4136973A Pending JPH05330917A (en) | 1992-05-28 | 1992-05-28 | Production of highly heat conductive silicon carbide sintered compact |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05330917A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100893896B1 (en) * | 2007-07-23 | 2009-04-20 | 한국에너지기술연구원 | Ceramic heat transfer plate for heat exchanger, and compact type ceramic heat exchanger having the same |
-
1992
- 1992-05-28 JP JP4136973A patent/JPH05330917A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100893896B1 (en) * | 2007-07-23 | 2009-04-20 | 한국에너지기술연구원 | Ceramic heat transfer plate for heat exchanger, and compact type ceramic heat exchanger having the same |
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