JPH0154303B2 - - Google Patents
Info
- Publication number
- JPH0154303B2 JPH0154303B2 JP59126288A JP12628884A JPH0154303B2 JP H0154303 B2 JPH0154303 B2 JP H0154303B2 JP 59126288 A JP59126288 A JP 59126288A JP 12628884 A JP12628884 A JP 12628884A JP H0154303 B2 JPH0154303 B2 JP H0154303B2
- Authority
- JP
- Japan
- Prior art keywords
- silicon carbide
- ultrafine
- sintered body
- sintering
- density
- 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.)
- Expired
Links
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 50
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 38
- 239000007789 gas Substances 0.000 claims description 14
- 239000002245 particle Substances 0.000 claims description 12
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims description 10
- 150000003961 organosilicon compounds Chemical class 0.000 claims description 8
- 125000005843 halogen group Chemical group 0.000 claims description 5
- 239000001257 hydrogen Substances 0.000 claims description 5
- 229910052739 hydrogen Inorganic materials 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 125000004430 oxygen atom Chemical group O* 0.000 claims description 4
- 239000011882 ultra-fine particle Substances 0.000 claims description 4
- 238000000197 pyrolysis Methods 0.000 claims description 3
- 238000010304 firing Methods 0.000 claims 1
- 238000005245 sintering Methods 0.000 description 15
- 238000000034 method Methods 0.000 description 14
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 12
- 238000010438 heat treatment Methods 0.000 description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- 230000001590 oxidative effect Effects 0.000 description 7
- 229910052786 argon Inorganic materials 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 238000005979 thermal decomposition reaction Methods 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 239000012071 phase Substances 0.000 description 5
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 4
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 229910002804 graphite Inorganic materials 0.000 description 4
- 239000010439 graphite Substances 0.000 description 4
- 238000000465 moulding Methods 0.000 description 4
- 238000010298 pulverizing process Methods 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 3
- 229910052796 boron Inorganic materials 0.000 description 3
- 239000001913 cellulose Substances 0.000 description 3
- 229920002678 cellulose Polymers 0.000 description 3
- 229920001971 elastomer Polymers 0.000 description 3
- 229910052734 helium Inorganic materials 0.000 description 3
- 239000001307 helium Substances 0.000 description 3
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 3
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 239000012188 paraffin wax Substances 0.000 description 3
- 150000004756 silanes Chemical class 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- UBHZUDXTHNMNLD-UHFFFAOYSA-N dimethylsilane Chemical group C[SiH2]C UBHZUDXTHNMNLD-UHFFFAOYSA-N 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 150000002894 organic compounds Chemical class 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229920000548 poly(silane) polymer Polymers 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000001272 pressureless sintering Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- VIPCDVWYAADTGR-UHFFFAOYSA-N trimethyl(methylsilyl)silane Chemical compound C[SiH2][Si](C)(C)C VIPCDVWYAADTGR-UHFFFAOYSA-N 0.000 description 2
- 239000012808 vapor phase Substances 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 239000002019 doping agent Substances 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 125000000816 ethylene group Chemical group [H]C([H])([*:1])C([H])([H])[*:2] 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 235000011187 glycerol Nutrition 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000010907 mechanical stirring Methods 0.000 description 1
- 229920000609 methyl cellulose Polymers 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 239000001923 methylcellulose Substances 0.000 description 1
- 125000001570 methylene group Chemical group [H]C([H])([*:1])[*:2] 0.000 description 1
- 229910052863 mullite Inorganic materials 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 229920001568 phenolic resin Polymers 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 1
- 125000000843 phenylene group Chemical group C1(=C(C=CC=C1)*)* 0.000 description 1
- 239000011505 plaster Substances 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 description 1
- 229920001223 polyethylene glycol Polymers 0.000 description 1
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 238000007665 sagging Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 229910000077 silane Inorganic materials 0.000 description 1
- -1 silicon halide Chemical class 0.000 description 1
- 238000003746 solid phase reaction Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- CZDYPVPMEAXLPK-UHFFFAOYSA-N tetramethylsilane Chemical compound C[Si](C)(C)C CZDYPVPMEAXLPK-UHFFFAOYSA-N 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
Landscapes
- Ceramic Products (AREA)
Description
(産業上の利用分野)
本発明は超微粒子状炭化けい素焼結体、特には
耐熱セラミツク成形体原料として有用とされる高
純度の超微粒子状炭化けい素焼結体に関するもの
である。
(従来の技術)
炭化けい素粉末は近年耐熱セラミツク材料とし
て注目されているものであるが、これについては
特に高純度で焼結性がよく、しかもサブミクロン
オーダーの微粉末での供給が要望されている。し
かし、従来公知のの固相反応で得られるものはα
型炭化けい素であるし、これにはまた微粉化のた
めに粉砕工程が必要とされるために高純度品を得
ることが難しいという不利があつた。また、この
種の炭化けい素の製造については一般式Ro
SiX4-o(こゝにRは水素原子またはアルキル基、
Xはハロゲン原子、nは1〜3の正数)で示され
るシランまたはこのシランと炭化水素化合物の高
温度熱分解反応やテトラメチルシランの熱分解反
応、あるいはこれらのプラズマ熱分解反応などの
気相反応による方法も知られており、これによれ
ば球状で微粉末状のβ型炭化けい素が得られるけ
れども、この前者の方法では未反応のハロゲン化
けい素の残留があり、後者の方法では得られた炭
化けい素が稠密化しにくいものでこの焼結には助
剤の添加が必須とされるという欠点がある。
(発明の構成)
本発明はこのような不利を解決した炭化けい素
焼結体の製造方法に関するものであり、これは分
子中に少なくとも1個のけい素―水素結合を有
し、SiX(Xはハロゲン原子または酸素原子)結
合を含まない有機けい素化合物を750〜1500℃で
気相熱分解させて得た、結晶子が50Å以下のβ型
炭化けい素の集合体であり、平均粒径が0.01〜1μ
である球状形状をもつ超微粒子状β型炭化けい素
を、非酸化性雰囲気下において1000〜1700℃で熱
処理し、ついで不活性雰囲気において1750〜2500
℃で焼成することを特徴とするものである。
これを説明すると、本発明者らはさきに分子中
に少なくとも1個のけい素―水素結合を有し、
SiX(Xはハロゲン原子または酸素原子)結合を
含まない有機けい素化合物を750℃以上で熱分解
させれば粉砕工程を経ることなしで超微粒子状の
炭化けい素を高純度でしかも収率よく得ることが
できることを見出し(特開昭59−39708号公報、
特願昭58−155911号、特願昭58−201202号明細書
参照)、このようにして得た炭化けい素は焼結助
剤の添加なしでも焼結するし、従来公知の炭化け
い素との混合物も極めて微量の焼結助剤で焼結で
きることを見出した(特願昭58−155910号、特願
昭58−213477号明細書参照)。そして、これにつ
いてさらに研究を進めたところ、上記した気相熱
分解法で得られた超微粒状のβ型炭化けい素を焼
結に先立つて非酸化性雰囲気下に1000〜1700℃で
熱処理するとさらに容易に高密度化した炭化けい
素焼結体を得ることができることを見出し、この
加熱処理条件などについての検討を重ね本発明を
完成させた。
本発明の方法によつて超微粒子状炭化けい素焼
結体を作るための超微粒子状β型炭化けい素は有
機けい素化合物の気相熱分解反応によつて得られ
るが、この有機けい素化合物はその分子中に少な
くとも1個のSi―H結合を含むが、しかしSiX結
合を含まないものであり、これは例えば一般式
R2o+2(Si)o〔こゝにRはその少なくとも1個が水
素原子である、水素原子またはメチル基、エチル
基、プロピル基、フエニル基、ビニル基などから
選ばれる1価の炭化水素基、nは1〜4の正数〕
で示されるシランまたはポリシラン類、および一
般式
〔こゝにRは前記と同じ、R′はメチレン基、エ
チレン基またはフエニレン基、mは1〜2の正
数〕で示されるシルアルキレン化合物またはシル
フエニレン化合物、あるいは同一分子中にこの両
者の主骨格をもつ化合物があげられる。そして、
この有機けい素化合物としては、次式
CH3SiH3、(CH3)2SiH2、(CH3)3SiH、
(C2H5)2SiH2、C3H7SiH3、CH2=CH・
CH3SiH2、C6H5SiH3、
で示されるシラン、ポリシランが例示され、これ
らはその1種または2種あるいは2種以上の混合
物として使用されるが、これらについては式
(Industrial Application Field) The present invention relates to an ultrafine silicon carbide sintered body, particularly a high purity ultrafine silicon carbide sintered body that is useful as a raw material for a heat-resistant ceramic molded body. (Prior art) Silicon carbide powder has recently attracted attention as a heat-resistant ceramic material, but there is a demand for it to be particularly high in purity and have good sinterability, and to be supplied in the form of submicron-order fine powder. ing. However, what can be obtained by the conventionally known solid phase reaction is α
type silicon carbide, and it also had the disadvantage that it was difficult to obtain a high-purity product because it required a pulverization step for pulverization. In addition, for the production of this type of silicon carbide, the general formula R o
SiX 4-o (where R is a hydrogen atom or an alkyl group,
(X is a halogen atom, n is a positive number from 1 to 3), or high-temperature thermal decomposition reactions of this silane and hydrocarbon compounds, thermal decomposition reactions of tetramethylsilane, or plasma thermal decomposition reactions of these. A method using a phase reaction is also known, and although this method yields spherical and finely powdered β-type silicon carbide, the former method leaves unreacted silicon halide, and the latter method However, the silicon carbide obtained is difficult to densify, and the sintering process requires the addition of an auxiliary agent. (Structure of the Invention) The present invention relates to a method for producing a silicon carbide sintered body that solves the above disadvantages, and has at least one silicon-hydrogen bond in the molecule, and SiX (X is It is an aggregate of β-type silicon carbide with crystallites of 50 Å or less, obtained by vapor-phase thermal decomposition of organosilicon compounds that do not contain halogen atoms or oxygen atoms) bonds at 750 to 1500 °C, and has an average particle size of 0.01~1μ
Ultrafine particle β-type silicon carbide with a spherical shape is heat treated at 1000 to 1700°C in a non-oxidizing atmosphere, and then heated to 1750 to 2500°C in an inert atmosphere.
It is characterized by being fired at ℃. To explain this, the present inventors first found that the molecule has at least one silicon-hydrogen bond,
If an organosilicon compound that does not contain SiX (X is a halogen atom or an oxygen atom) bond is thermally decomposed at 750°C or higher, ultrafine silicon carbide can be produced in high purity and high yield without going through a pulverization process. found that it is possible to obtain
(See Japanese Patent Application No. 58-155911 and Japanese Patent Application No. 58-201202), the silicon carbide thus obtained can be sintered without the addition of a sintering aid, and is different from conventionally known silicon carbide. It has been found that a mixture of the above can also be sintered with an extremely small amount of sintering aid (see Japanese Patent Application No. 155910/1982 and Japanese Patent Application No. 213477/1983). Further research on this topic revealed that ultrafine β-type silicon carbide obtained by the above-mentioned gas phase pyrolysis method was heat-treated at 1000 to 1700°C in a non-oxidizing atmosphere prior to sintering. Furthermore, they discovered that it was possible to easily obtain a highly densified silicon carbide sintered body, and completed the present invention after repeated studies on the heat treatment conditions. The ultrafine β-type silicon carbide for producing the ultrafine silicon carbide sintered body by the method of the present invention is obtained by a gas phase pyrolysis reaction of an organosilicon compound. contains at least one Si--H bond in its molecule, but no SiX bond, for example, the general formula
R 2o+2 (Si) o [Here, R is a hydrogen atom, at least one of which is a hydrogen atom, or a monovalent hydrocarbon selected from a methyl group, an ethyl group, a propyl group, a phenyl group, a vinyl group, etc. base, n is a positive number from 1 to 4]
Silanes or polysilanes represented by and the general formula [Here, R is the same as above, R' is a methylene group, ethylene group, or phenylene group, and m is a positive number of 1 to 2. Examples include compounds with a skeleton. and,
This organosilicon compound has the following formula: CH 3 SiH 3 , (CH 3 ) 2 SiH 2 , (CH 3 ) 3 SiH,
(C 2 H 5 ) 2 SiH 2 , C 3 H 7 SiH 3 , CH 2 = CH・
CH3SiH2 , C6H5SiH3 , _ Examples of silanes and polysilanes shown by the formula
【式】〔こゝにnは正数〕で示されるジ
メチルポリシランを350℃以上の温度で熱分解さ
せて得られるジメチルポリシランを主体とするメ
チルハイドロジエンシラン類が好ましいものとさ
れる。なお、これらの有機けい素化合物は従来公
知の方法で製造することができるが、これらは蒸
留工程で容易に高純度化することができ、粉砕工
程が不要なために本反応によつて得られる炭化け
い素も極めて純度の高いものになるという有利性
が与えられる。
この有機けい素化合物の気相熱分解反応はこれ
を750〜1500℃に加熱した反応帯域に水素ガスま
たは窒素、ヘリウム、アルゴンなどの不活性ガス
をキヤリヤーガスと共に導入して熱分解させれば
よく、この反応によれば結晶子が50Å以下のβ型
炭化けい素の集合体で、平均粒径が0.01〜1μであ
る球状形状をもつ超微粒子状のβ型多結晶炭化け
い素が得られる。
本発明の超微粒子状炭化けい素焼結体の製造は
このようにして得た超微粒子状のβ型多結晶炭化
けい素を焼結するのであるが、この焼結に当つて
は焼結に先立つて、予じめこれを非酸化性雰囲気
下で1000〜1700℃に加熱処理することが必要とさ
れる。この熱処理によつて超微粒子状β型多結晶
炭化けい素中に含まれている未分解の有機結合が
完全に分解されると共に集合体中のβ型炭化けい
素結晶子のみだれが修正されるので、これはつい
で行なわれる焼結によつてより高密度の焼結体と
されるのであるが、この熱処理は常圧または減圧
下で行えばよく、これはまた機械的撹拌下で行な
つてもよい。しかし、この熱処理はこれを1000℃
以下とすると未分解有機結合の分解速度が遅くな
つてこの処理時間が長くなり、1700℃以上では結
晶子の急激な成長と共に一部に焼結が始まるので
1000〜1700℃の温度範囲とすることが必要とされ
るし、このガス雰囲気については酸化性雰囲気と
すると超微粒子状炭化けい素が反応性に富むもの
であるために表面が酸化されて焼結体密度があが
らず、さらに耐熱性が劣るようになるという不利
が生じるので、これは窒素、水素、アルゴン、ヘ
リウムガスなどの非酸化性雰囲気下とすることが
必要とされる。なお、この処理濃度、処理時間は
特にこれを限定する必要がなく任意とされるが、
1000℃では2時間、1700℃では30分位が経済的で
ある。その場合に雰囲気ガス中にB2、H6、PH3
などのドーピング剤を添加してこの炭化けい素の
電気特性、焼結特性を調節することも任意とされ
る。
上記のように熱処理された炭化けい素はついで
成形し、焼結すればよいが、この成形はセラミツ
ク業界で公知の方法で行えばよく、これは例えば
ダイプレス法で行なえばよい。この成形には結合
剤としては、加熱により分解生成物が残存しない
ような有機化合物、例えばパラフイン、低分子量
セルロース誘導体、フエノール樹脂などを単独
で、あるいはアセトンなどに溶解して使用しても
よいが、これら結合剤を使用せずに直接加圧、成
形し焼結してもよい。また、これをチユーブ、ル
ツボなどの複雑な成形品とするためにはラバープ
レスなどを用いて成形すればよいが、より精密な
成形品を得るためには生の賦形体をその焼結前に
研削するか、あるいはスライスなどの機械加工を
施すことがよい。なお、この成形はスリツプキヤ
スト法で行なつてもよいが、この場合には炭化け
い素粉末にポリエチレングリコール、低分子量セ
ルロース誘導体、パラフインなどの可塑剤とポリ
ビニルブチラールなどの結合剤を添加し、水中に
分散させてから焼石こう型内に流し込めばよい。
またセルロース誘導体などと水との混合物からな
る成形可能なペーストは押出成形、射出成形、ロ
ール成形などを行なつてもよい。
また、このようにして得られた成形体はついで
焼結することによつて焼結体とされるが、これに
は焼結に先立つて添加した有機化合物を揮発させ
る。この焼結は常圧またはガス加圧、プレス加圧
などの加圧下のいずれで行なつてもよい。しかし
この加熱温度についてはこれが低すぎると焼結不
足となるし、高密度品を得るという目的において
はできるだけ高温とすることがよいが、これを
2500℃以上とすると粒子の成長によつて強度が低
下することがあり、また経済的にも不利となるの
で、これは、1750〜2500℃、好ましくは1900〜
2300℃とすることがよい。また、焼結はこれらを
不活性雰囲気下とする必要があるが、これはアル
ゴン、窒素、ヘリウムガスの存在下とすればよ
い。なお、この焼結工程に先立つて前記した成形
品についての切削加工を実施する場合には、これ
を必要に応じ仮焼してもよいが、この温度は1500
℃以下とすることがよく、この温度はその機械加
工に必要とされる強度に応じて定めればよい。
他方、本発明の方法で製造された焼結体はこれ
を上記した炭化けい素の超微粒子だけで製造する
と高価なものとなるので、これは市販の平均粒径
が5μ以下の炭化けい素粒子を添加してもよく、
これによれば価格面からの工業的な有利性が与え
られる。しかし、この種の市販の炭化けい素の焼
結に当つては前記したような焼結助剤の添加が必
要とされ、これについては例えば0.15〜5重量%
のほう素とこの原料粉体中に含まれる遊離な酸素
を除去するための0.1〜5重量%の炭素の添加が
必要とされるのであるが、本発明による場合には
上記した炭化けい素の超微粒子100〜50重量部に
対する市販の炭化けい素添加量を50重量部とした
場合でも0.15重量%、0.1重量%とすることがで
き、これは市販炭化けい素の減量と共にその添加
量を減じることができるので、このほう素、炭素
の共存による不利を最少限にすることができると
いう有利性も与えられる。
これを要するに本発明は分子中に少なくとも1
個のけい素―水素結合を有し、SiX(Xはハロゲ
ン原子または酸素原子)結合を含まない有機けい
素化合物を750〜1500℃で気相熱分解させて得た、
結晶子が50Å以下のβ型炭化けい素集合体で平均
粒径が0.01〜1μである球状形状をもつ超微粒子状
β型多結晶炭化けい素を非酸化性雰囲気下におい
て1000〜1700℃で熱処理してから焼結させて超微
粒子状炭化けい素焼結体を製造する方法に関する
ものであり、このようにして得られた焼結体はそ
の密度が理論密度の90%である2.89g/c.c.以上の
ものとして容易に取得されるので、強度が必要と
されるガスタービン翼、自動車部品用として有用
とされるほか、高純度であることから各種機械部
品、電気部品として利用することができるという
実用性をもつものである。
つぎに本発明の実施例をあげる。
実施例1〜5、比較例1
内径70mm、長さ1500mmのムライト製炉心管を備
えた縦型管状電気炉を1150℃に加熱し、こゝにテ
トラメチルジシラン10容量%を含む水素ガスを
200/時で導入して8時間反応させたところ、
炭化けい素粉末574.3g(収率93%)が得られた。
このものは電子顕微鏡のβ―SiC(1、1、1)
回折による暗視野像の測定結果から50Å以下のβ
型炭化けい素の集合体で平均粒径が0.1〜0.4μで
ある球状形状をもつ超微粒子状のβ型多結晶炭化
けい素であることが確認された。
ついでこの超微粒子状炭化けい素50gを直径
100mmφ、高さ100mmの黒鉛製容器に入れて第1表
に示した条件で熱処理を行なつたのち、この炭化
けい素3gに0.3重量%のほう素粉末(レアメタ
リツク社製)と1重量%のパラフインを含むアセ
トン溶液10mlを添加して超音波混合した。この混
合物を5mm×7mm×5mmの金型に入れ、150Kg/
cm2で加圧し、さらにラバープレスで1.5t/cm2の加
圧処理を行なつた。
つぎにこの試料片を常圧焼結用のカーボン型に
入れ、アルゴンガス雰囲気中、大気圧下において
2200℃で1時間無加圧焼結を行なつて焼結体を作
り、この密度を測定したところ、第1表に併記し
たとおりの結果が得られたが、これには比較例と
して上記した熱処理を行なわずに焼結したものに
ついての結果も併記した。Methylhydrodienesilanes, which are mainly composed of dimethylpolysilane obtained by thermally decomposing dimethylpolysilane represented by the formula [where n is a positive number] at a temperature of 350° C. or higher, are preferred. These organosilicon compounds can be produced by conventionally known methods, but they can be easily purified by a distillation process, and a pulverization process is not required, so they can be obtained by this reaction. The silicon carbide also has the advantage of being extremely pure. The gas phase thermal decomposition reaction of this organosilicon compound can be carried out by introducing hydrogen gas or an inert gas such as nitrogen, helium, or argon together with a carrier gas into a reaction zone heated to 750 to 1500°C. According to this reaction, ultrafine β-type polycrystalline silicon carbide, which is an aggregate of β-type silicon carbide with crystallites of 50 Å or less and has a spherical shape and an average particle size of 0.01 to 1 μm, is obtained. In the production of the ultrafine-grained silicon carbide sintered body of the present invention, the ultrafine-grained β-type polycrystalline silicon carbide thus obtained is sintered. Therefore, it is necessary to heat-treat this in advance at 1000 to 1700°C in a non-oxidizing atmosphere. This heat treatment completely decomposes the undecomposed organic bonds contained in the ultrafine β-type polycrystalline silicon carbide, and also corrects the sagging of the β-type silicon carbide crystallites in the aggregate. Therefore, this is then sintered to form a sintered body with higher density, but this heat treatment can be performed under normal pressure or reduced pressure, and it can also be performed under mechanical stirring. Good too. However, this heat treatment lowers this temperature to 1000℃.
If the temperature is below 1,700℃, the decomposition rate of undecomposed organic bonds will slow down and the processing time will become longer, and if the temperature is higher than 1700℃, sintering will begin in some parts with rapid growth of crystallites.
It is necessary to keep the temperature in the range of 1000 to 1700℃, and if the gas atmosphere is oxidizing, the ultrafine silicon carbide is highly reactive, so the surface will be oxidized and the density of the sintered body will decrease. This has the disadvantage that the heat resistance is not increased and the heat resistance is deteriorated, so it is necessary to use a non-oxidizing atmosphere such as nitrogen, hydrogen, argon or helium gas. Note that the treatment concentration and treatment time do not need to be particularly limited and are arbitrary.
2 hours at 1000℃ and 30 minutes at 1700℃ are economical. In that case, B 2 , H 6 , PH 3 in the atmospheric gas
It is also optional to adjust the electrical properties and sintering properties of this silicon carbide by adding doping agents such as. The silicon carbide heat-treated as described above may then be shaped and sintered, and this shaping may be performed by a method known in the ceramic industry, such as a die press method. As a binder for this molding, organic compounds that do not leave decomposition products when heated, such as paraffin, low molecular weight cellulose derivatives, phenolic resins, etc., may be used alone or dissolved in acetone etc. , it is also possible to press, mold, and sinter directly without using these binders. In addition, in order to make complex molded products such as tubes and crucibles, it is possible to mold them using a rubber press, but in order to obtain more precise molded products, it is necessary to It is preferable to perform mechanical processing such as grinding or slicing. Note that this molding may be performed by the slip cast method, but in this case, a plasticizer such as polyethylene glycol, a low molecular weight cellulose derivative, or paraffin, and a binder such as polyvinyl butyral are added to the silicon carbide powder, and the molding is performed in water. After dispersing the mixture, pour it into a baked plaster mold.
Further, a moldable paste made of a mixture of a cellulose derivative or the like and water may be subjected to extrusion molding, injection molding, roll molding, or the like. Further, the molded body thus obtained is then sintered to form a sintered body, and the organic compound added is volatilized prior to sintering. This sintering may be performed under normal pressure or under pressure such as gas pressure or press pressure. However, if this heating temperature is too low, sintering will be insufficient.For the purpose of obtaining high-density products, it is better to set the heating temperature as high as possible;
If the temperature is higher than 2500℃, the strength may decrease due to particle growth, and it is also economically disadvantageous.
It is preferable to set the temperature to 2300℃. Furthermore, sintering requires these to be under an inert atmosphere, but this may be done in the presence of argon, nitrogen, or helium gas. In addition, if the above-mentioned molded product is cut prior to this sintering step, it may be calcined if necessary, but this temperature should not exceed 1500℃.
℃ or less, and this temperature may be determined depending on the strength required for machining. On the other hand, the sintered body manufactured by the method of the present invention would be expensive if it were manufactured only from the above-mentioned ultrafine silicon carbide particles, so it is not possible to use commercially available silicon carbide particles with an average particle size of 5μ or less. You may also add
This gives an industrial advantage in terms of price. However, when sintering this type of commercially available silicon carbide, it is necessary to add a sintering aid as described above, for example, 0.15 to 5% by weight.
It is necessary to add 0.1 to 5% by weight of carbon to remove boron and free oxygen contained in the raw material powder, but in the case of the present invention, the above-mentioned silicon carbide is added. Even if the amount of commercially available silicon carbide added to 100 to 50 parts by weight of ultrafine particles is 50 parts by weight, it can be added to 0.15% by weight or 0.1% by weight, which means that the amount added can be reduced as the amount of commercially available silicon carbide is reduced. Therefore, there is an advantage that the disadvantages due to the coexistence of boron and carbon can be minimized. In short, the present invention provides at least one
obtained by vapor-phase thermal decomposition of an organosilicon compound having silicon-hydrogen bonds and no SiX (X is a halogen atom or an oxygen atom) bond at 750 to 1500°C.
Heat treatment of β-type polycrystalline silicon carbide in a non-oxidizing atmosphere at 1000-1700℃ in a non-oxidizing atmosphere of β-type polycrystalline silicon carbide aggregates with crystallites of 50 Å or less and a spherical shape with an average particle size of 0.01-1μ. This invention relates to a method for producing an ultrafine silicon carbide sintered body by sintering the sintered body, and the sintered body thus obtained has a density of 2.89 g/cc or more, which is 90% of the theoretical density. Because it is easily obtained as a substance, it is useful for gas turbine blades and automobile parts that require strength, and because of its high purity, it can be used for various mechanical and electrical parts. It has a nature. Next, examples of the present invention will be given. Examples 1 to 5, Comparative Example 1 A vertical tubular electric furnace equipped with a mullite furnace tube with an inner diameter of 70 mm and a length of 1500 mm was heated to 1150°C, and hydrogen gas containing 10% by volume of tetramethyldisilane was introduced into it.
When introduced at a rate of 200/hour and reacted for 8 hours,
574.3 g (yield 93%) of silicon carbide powder was obtained. This is β-SiC (1, 1, 1) in an electron microscope.
β of less than 50 Å from the measurement results of dark-field images by diffraction.
It was confirmed that the particles were β-type polycrystalline silicon carbide in the form of ultrafine particles with a spherical shape and an average particle size of 0.1 to 0.4μ. Next, 50g of this ultrafine particulate silicon carbide was
After placing it in a graphite container with a diameter of 100 mm and a height of 100 mm and heat-treating it under the conditions shown in Table 1, 3 g of silicon carbide was mixed with 0.3% by weight of boron powder (manufactured by Rare Metallic Co., Ltd.) and 1% by weight. 10 ml of an acetone solution containing paraffin was added and mixed ultrasonically. This mixture was put into a 5mm x 7mm x 5mm mold and 150Kg/
A pressure of 1.5 t/cm 2 was applied using a rubber press. Next, this sample piece was placed in a carbon mold for pressureless sintering, and placed in an argon gas atmosphere under atmospheric pressure.
Pressureless sintering was performed at 2200°C for 1 hour to produce a sintered body, and the density of the sintered body was measured, and the results shown in Table 1 were obtained. The results for those sintered without heat treatment are also shown.
【表】【table】
【表】
実施例6、比較例2
前記の実施例1〜5におけるテトラメチルジシ
ランをジメチルシランと替えて同様に処理したと
ころ、50A以下のβ型炭化けい素集合体で平均粒
径が0.1〜0.5μである球状形状をもつ超微粒子状
β型多結晶炭化けい素262.4gが得られたので、
これを前例と同じ黒鉛製容器中で窒素ガス雰囲気
において1300℃で1時間加熱処理を行ない、この
30gにほう素0.9g、メチルセルロース・MC−
400〔信越化学工業(株)製商品名〕1gとグリセリン
1gとを水6gに溶解した溶液中に分散させ3本
ロールで混合してシート状体として取り出した。
つぎにこのシートを50mm×2mm×50mmに切断し
て風乾後ラバープレスで1.5Kg/cm2に加圧処理し、
窒素ガス中において1200℃で1時間加熱して有機
物を揮発させてから前例と同様に焼結処理したと
ころ、密度が3.04g/c.c.(対理論密度94.7%)の
焼結体が得られたが、比較のために行なつた上記
における熱処理を行なわなかつた焼結体の密度は
2.79g/c.c.であつた(比較例2)。
実施例 7
上記の実施例6で得られた超微粉状β型多結晶
炭化けい素を黒鉛製容器中においてアルゴンガス
雰囲気中1400℃で1時間熱処理を行なつたのち、
このもののけい素、炭素、酸素の含有量を分析し
たところ、第2表に示したとおりの結果が得ら
れ、この熱処理によつてもその組成に変化のない
ことが認められた。[Table] Example 6, Comparative Example 2 When the tetramethyldisilane in Examples 1 to 5 was replaced with dimethylsilane and the same treatment was performed, β-type silicon carbide aggregates of 50A or less with an average particle size of 0.1 to 262.4g of ultrafine particulate β-type polycrystalline silicon carbide with a spherical shape of 0.5μ was obtained.
This was heat-treated at 1300℃ for 1 hour in a nitrogen gas atmosphere in the same graphite container as in the previous example.
0.9g of boron per 30g, methylcellulose/MC-
400 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) and 1 g of glycerin were dispersed in a solution of 6 g of water, mixed with three rolls, and taken out as a sheet. Next, this sheet was cut into 50 mm x 2 mm x 50 mm, air-dried, and then pressurized to 1.5 kg/cm 2 using a rubber press.
When heated in nitrogen gas at 1200°C for 1 hour to volatilize the organic matter and then sintered in the same manner as in the previous example, a sintered body with a density of 3.04 g/cc (94.7% relative to theoretical density) was obtained. , the density of the sintered body that was not subjected to the above heat treatment for comparison is
It was 2.79 g/cc (Comparative Example 2). Example 7 The ultrafine powdered β-type polycrystalline silicon carbide obtained in Example 6 above was heat-treated at 1400°C for 1 hour in an argon gas atmosphere in a graphite container, and then
When the silicon, carbon, and oxygen contents of this product were analyzed, the results shown in Table 2 were obtained, and it was found that there was no change in the composition even after this heat treatment.
【表】
なお、この炭化けい素について実施例1と同じ
条件で焼結したところ、このものは密度が3.15
g/c.c.(対理論密度98.1%)で強度が62Kg/cm2で
あつたが、熱処理をしない比較例3のものは密度
が2.90g/c.c.で強度も34Kg/cm2であつた。
実施例 8
実施例1におけるテトラメチルジシシランを含
む水素ガスをジメチルシランとH
(CH3)2SiCH2Si(CH3)2Hとの1:1の混合物20
容量%を含む水素ガスとし、これを1250℃で気相
熱分解させたところ、50Å以下のβ型炭化けい素
集合体で平均粒径が0.1〜0.3μである微粒子状β
型多結晶炭化けい素が得られた。
つぎにこれを黒鉛容器中において真空中で1250
℃で2時間加熱処理したのち、焼結助剤を添加せ
ずに40mmφのホツトプレス用カーボン型に入れて
減圧脱気し、ついで系内をアルゴンガス雰囲気下
としてから200Kg/cm2の加圧下に2100℃で50分間
加熱したところ、得られた焼結体の密度は3.19
g/c.c.(対理論密度99.4%)であつたが、比較の
ために作成した上記の熱処理を行なわなかつたも
のの焼結体の密度は3.10g/c.c.(対理論密度96.6
%)であつた。[Table] When this silicon carbide was sintered under the same conditions as in Example 1, the density was 3.15.
g/cc (98.1% relative to theoretical density) and had a strength of 62 Kg/cm 2 , whereas the material of Comparative Example 3, which was not heat-treated, had a density of 2.90 g/cc and a strength of 34 Kg/cm 2 . Example 8 Hydrogen gas containing tetramethyldisisilane in Example 1 was mixed with dimethylsilane and H
1:1 mixture with (CH 3 ) 2 SiCH 2 Si(CH 3 ) 2 H20
When hydrogen gas containing % by volume was pyrolyzed in the gas phase at 1250℃, fine particles of β-type silicon carbide aggregates of 50 Å or less and an average particle size of 0.1 to 0.3 μ were obtained.
type polycrystalline silicon carbide was obtained. Next, this was placed in a graphite container under vacuum at 1250°C.
After heat treatment at ℃ for 2 hours, it was placed in a 40 mm diameter carbon mold for hot press without adding any sintering aid and degassed under reduced pressure.Then, the inside of the system was placed under an argon gas atmosphere and then placed under a pressure of 200 kg/cm 2 . When heated at 2100℃ for 50 minutes, the density of the obtained sintered body was 3.19
g/cc (99.4% relative to theoretical density), but the density of a sintered body prepared for comparison without the above heat treatment was 3.10 g/cc (96.6% relative to theoretical density).
%).
Claims (1)
を有し、SiX(Xはハロゲン原子または酸素原子)
結合を含まない有機けい素化合物を750〜1500℃
で気相熱分解させて得た、結晶子が50Å以下のβ
型炭化けい素の集合体であり、平均粒径が0.01〜
1μである球状形状をもつ超微粒子状β型多結晶
炭化けい素を、非酸化性雰囲気下において1000〜
1700℃で熱処理し、ついで不活性雰囲気において
1750〜2500℃で焼成することを特徴とする超微粒
子状炭化けい素焼結体の製造方法。1 Has at least one silicon-hydrogen bond in the molecule, SiX (X is a halogen atom or an oxygen atom)
Organosilicon compounds containing no bonds at 750-1500℃
β with crystallites less than 50 Å obtained by gas phase pyrolysis in
It is an aggregate of silicon carbide with an average particle size of 0.01~
Ultrafine particle β-type polycrystalline silicon carbide with a spherical shape of 1μ is heated to 1000~1μ in a nonoxidizing atmosphere.
Heat treated at 1700℃ and then in an inert atmosphere
A method for producing an ultrafine silicon carbide sintered body, characterized by firing at 1750 to 2500°C.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP59126288A JPS616178A (en) | 1984-06-19 | 1984-06-19 | Superfine particle silicon carbide sintered body |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP59126288A JPS616178A (en) | 1984-06-19 | 1984-06-19 | Superfine particle silicon carbide sintered body |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS616178A JPS616178A (en) | 1986-01-11 |
JPH0154303B2 true JPH0154303B2 (en) | 1989-11-17 |
Family
ID=14931498
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP59126288A Granted JPS616178A (en) | 1984-06-19 | 1984-06-19 | Superfine particle silicon carbide sintered body |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS616178A (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2585506B2 (en) * | 1984-11-14 | 1997-02-26 | 株式会社日立製作所 | Silicon carbide sintered body and method for producing the same |
JPS638263A (en) * | 1986-06-26 | 1988-01-14 | 新技術事業団 | Manufacture of sic superfine sintered body |
-
1984
- 1984-06-19 JP JP59126288A patent/JPS616178A/en active Granted
Also Published As
Publication number | Publication date |
---|---|
JPS616178A (en) | 1986-01-11 |
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