JPH0151443B2 - - Google Patents
Info
- Publication number
- JPH0151443B2 JPH0151443B2 JP56144758A JP14475881A JPH0151443B2 JP H0151443 B2 JPH0151443 B2 JP H0151443B2 JP 56144758 A JP56144758 A JP 56144758A JP 14475881 A JP14475881 A JP 14475881A JP H0151443 B2 JPH0151443 B2 JP H0151443B2
- Authority
- JP
- Japan
- Prior art keywords
- silicon carbide
- powder
- type
- aluminum
- type silicon
- 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 111
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 98
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 55
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 52
- 229910052782 aluminium Inorganic materials 0.000 claims description 34
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 25
- 239000000377 silicon dioxide Substances 0.000 claims description 25
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 23
- 235000012239 silicon dioxide Nutrition 0.000 claims description 21
- 229910052757 nitrogen Inorganic materials 0.000 claims description 20
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 15
- 239000002994 raw material Substances 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 11
- -1 aluminum compound Chemical class 0.000 claims description 10
- 239000012298 atmosphere Substances 0.000 claims description 5
- 230000001590 oxidative effect Effects 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 3
- 239000000843 powder Substances 0.000 description 20
- 238000004519 manufacturing process Methods 0.000 description 19
- 238000006243 chemical reaction Methods 0.000 description 18
- 229910052581 Si3N4 Inorganic materials 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 7
- 229910052799 carbon Inorganic materials 0.000 description 6
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 238000002441 X-ray diffraction Methods 0.000 description 3
- 238000005452 bending Methods 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 239000006229 carbon black Substances 0.000 description 3
- 239000000919 ceramic Substances 0.000 description 3
- 229910002804 graphite Inorganic materials 0.000 description 3
- 239000010439 graphite Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 229910021486 amorphous silicon dioxide Inorganic materials 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- BNGXYYYYKUGPPF-UHFFFAOYSA-M (3-methylphenyl)methyl-triphenylphosphanium;chloride Chemical compound [Cl-].CC1=CC=CC(C[P+](C=2C=CC=CC=2)(C=2C=CC=CC=2)C=2C=CC=CC=2)=C1 BNGXYYYYKUGPPF-UHFFFAOYSA-M 0.000 description 1
- VXEGSRKPIUDPQT-UHFFFAOYSA-N 4-[4-(4-methoxyphenyl)piperazin-1-yl]aniline Chemical compound C1=CC(OC)=CC=C1N1CCN(C=2C=CC(N)=CC=2)CC1 VXEGSRKPIUDPQT-UHFFFAOYSA-N 0.000 description 1
- 229910002012 Aerosil® Inorganic materials 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 239000004115 Sodium Silicate Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 1
- 239000012300 argon atmosphere Substances 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000007806 chemical reaction intermediate Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 229910021488 crystalline silicon dioxide Inorganic materials 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 238000007731 hot pressing Methods 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052754 neon Inorganic materials 0.000 description 1
- GKAOGPIIYCISHV-UHFFFAOYSA-N neon atom Chemical compound [Ne] GKAOGPIIYCISHV-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000000634 powder X-ray diffraction Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000005049 silicon tetrachloride Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 229910052911 sodium silicate Inorganic materials 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Description
本発明は2H型を大量に含む炭化珪素粉末及び
その製造方法を提供するものである。詳しくは
2H型炭化珪素を60容量％以上含む2H型炭化珪素
とβ型炭化珪素とよりなり且つ窒素３重量％以
下、を含む高Ｈ型炭化珪素粉末及びその製造方法
に関するものである。
従来炭化珪素はα型及びβ型の炭化珪素が公知
であり、種々の用途に使用される優れたセラミツ
クである。しかし、これらの炭化珪素は、焼結温
度が高い欠点を有していた。そのためにより低温
度で焼結出来る2H型炭化珪素が期待されていた。
しかしながら2H型炭化珪素の存在は知られてい
ても、高含有量の粉末を製造することは極めて難
しく工業的に優れた技術は確立されていない。例
えば特開昭54−121298号明細書には、二酸化珪素
と炭素粉末とを、比較的多量のアルミニウムの存
在下、減圧下に、1200〜1500℃の温度で反応させ
て2H型炭化珪素に富む微粉状炭化珪素の製造方
法が提案されている。この方法は従来の方法に比
べれば2H型炭化珪素を多量に含む粉末を得る優
れた方法であるが、生成物中の2H型炭化珪素を
50％に達せしめることは困難であり、更に、減圧
操作を必要とする等のため必ずしも工業的に満足
出来る方法或いは粉末とは言えない。また物性的
にもしばしばアルミニウム含有率が高くなり、好
ましくない。
本発明者等は上記技術課題を解決するため鋭意
研究を積重ねた結果、窒素ガス雰囲気中で1550℃
以上の温度でアルミニウムが存在する二酸化珪素
と炭素粉末を反応させた結果、2H型炭化珪素が
多量に含まれた炭化珪素粉末が得られることを見
出し、本発明を完成し提案するに至つた。
即ち、本発明に準ずる方法により容易に2H型
炭化珪素を40容量％以上含む主として2H型炭化
珪素とβ型炭化珪素とよりなり且つ窒素が３重量
％以下含まれてなる2H型炭化珪素を含む粉末を
得ることが可能となるのである。炭化珪素中の
2H型含有量が40容量％以下では、本発明の目的
である比較的低温下での焼結性が得られなくな
る。2H型が50％を超える量含まれていると焼成
は比較的容易となるが、得られる焼結体が多少強
度的に十分でない。2H型が60容量％を超えるも
のは容易に焼結も可能となり、しかも十分な強度
が得られるのである。従つて本発明は、2H型炭
化珪素を60容量％以上含み、その余は主としてβ
型炭化珪素よりなり、且つ窒素を３重量％以下、
その他の不可避的に含まれる小量成分とよりなる
高2H型炭化珪素粉末を提供するものである。ま
た本発明は、二酸化珪素と炭素粉末とを、アルミ
ニウム又はアルミニウム化合物が存在し且つ窒素
ガス又は窒素ガスを含む非酸化性雰囲気下に1550
℃以上の温度で反応させることによる高2H型炭
化珪素粉末の製造方法を提供するものである。
本発明の炭化珪素は2H型炭化珪素を60容量％
以上含み、その余は主としてβ型炭化珪素よりな
る炭化珪素粉末である。また本発明の炭化珪素は
その製造に基因する窒素成分を３重量％以下含有
している。2H型炭化珪素が40容量％以下含まれ
る炭化珪素は例えば前記特開昭54−121298号に実
施例の１部として示されているように、いくつか
の報文で知られている。しかしながら2H型を、
例えば55容量％以上に含有する工業的に得られた
炭化珪素粉末は知られていない。勿論2H型炭化
珪素自体は公知であるが、低含有率で2H型を含
有する、炭化珪素から、2H型を工業的に濃縮し
て、高2H型炭化珪素粉末を得ることは不可能で
ある。従つて、例えば60容量％を超える程の高
2H型炭化珪素を得るためには、製造時に高2H型
炭化珪素として得なければならないのである。し
かしながら、本発明のように60容量％以上の2H
型炭化珪素を含む炭化珪素粉末を得る方法は従来
知られていなかつたのである。しかも本発明にあ
つては、高2H型とする製造工程に由来して、炭
化珪素粉末中に窒素が３重量％以下一般には0.01
〜2.0重量％の範囲で含まれている。かかる炭化
珪素は新規なものである。上記窒素がどのような
形で本発明の炭化珪素中に含まれているのか、ま
た上記窒素が本発明の炭化珪素の性状にどのよう
に影響を与えているのか現在必ずしも明確ではな
い。しかし従来知られている炭化珪素と比較する
とき本発明の炭化珪素粉末は次のような利点を有
するので、これらの性状を付与するのに強く関係
しているものと推測している。即ち2000℃で、10
分間ホツトプレスして得た焼結体は1500℃に於け
る曲げ強度50Kg／mm2以上の強度を有する。これは
従来の2H型炭化珪素を例えば、40容量％以下の
如く比較的小量含有する炭化珪素焼結体はアルミ
ニウム含有量が多いことと併せて高温強度が極端
に低下し実用に供し得るものが得られないのに比
べて大巾な改良と言える。また従来2H型炭化珪
素は1500℃以下では安定であるが、1500℃を超え
るとβ型炭化珪素が生成することが知られていた
にもかかわらず、本発明の2H型炭化珪素は1500
℃以下の温度では実質的に生成せず、安定領域で
はないはずの1550℃以上好ましくは1575℃以上更
に好ましくは1600℃以上で安定して生成する。こ
れらの差異は本発明の炭化珪素が単に純度が良好
であることだけによるものでなく、炭化珪素中の
含有窒素成分が何らかの形で関与しているものと
推測している。
本発明の炭化珪素に含まれる窒素成分がどのよ
うな形状をなしているのかは現在なお明確ではな
い。本発明の炭化珪素を低温例えば1500℃程度で
製造しようとすれば含有窒素が30重量％以上とな
り明らかに窒化珪素（Si3N4）として含まれてい
る。しかし上記反応温度が1550℃、1600℃と高温
になれば含有窒素は極端に少くなり、Ｘ線回折に
よつても、もはや窒化珪素の存在を確認すること
は出来ない。このような傾向はあるが前記利点か
ら推測して含有窒素は窒化珪素として含有されて
いるのではなく炭化珪素中、2H型炭化珪素の生
成にアルミニウムと共に触媒的に関与するか反応
中間体の生成に関与しそのまま炭化珪素中に取込
まれて高温安定性に関与しているのではないかと
推定している。しかしながら含有窒素成分の含有
量は炭化珪素の純度上は出来るだけ少量の方が好
ましく、工業的に供する炭化珪素を得る場合には
0.05〜1.5重量％を目標とするのが好適であろう。
本発明の炭化珪素は前記のように、60容量％以
上の2H型炭化珪素とβ型炭化珪素とから主とし
て構成される粉末であるが、その製法において触
媒的に使用するアルミニウムが最高4.0重量％含
まれることがありうる。しかしながら上記アルミ
ニウムの含有量は本発明の炭化珪素を製造する時
の製造条件によつて影響をうけ0.05重量％或いは
それ以下となる場合がある。従つてアルミニウム
はその製造上の不純物として不可避的に含有さ
れ、その含有量は2H型炭化珪素の生成に悪影響
を及ぼさない限り、少量の方が好ましい。後述す
る通常の方法で炭化珪素を得る場合は一般に0.01
〜1.5重量％の範囲で含まれる場合が多い。
本発明の炭化珪素は前記のような組成であれば
よく、その製造方法は特に限定されるものではな
い。一般に好適に製造される代表的な方法は下記
の通りである。
本発明の炭化珪素を製造する原料の１つは二酸
化珪素である。該二酸化珪素は特に限定されず窒
化珪素、炭化珪素等の原料として公知のものが使
用出来る。一般には無定形の二酸化珪素例えば含
水珪酸、無水珪酸等が好適に使用される。石英の
ような結晶性二酸化珪素を使用する場合は微粉に
して使用する必要がある。勿論前記無定形の二酸
化珪素は通常粉状体であり、そのまま又は凝集粒
子の場合は機械的に再分散し例えば10μ以下とし
て使用すればよい。
本発明の炭化珪素を製造する原料の他の１つは
炭素粉末である。粉末状の炭素であれば特に限定
されず、一般には10μ以下のものが好適に採用さ
れる。本発明の炭化珪素はその粒子径が上記使用
する炭素粉末の粒子径に影響をうける傾向があ
る。従つて炭化珪素を粉状で得ようとすれば、原
料の炭素粉末は微粒子のものを使用するか、微粒
子に粉砕して使用する必要がある。一般にはカー
ボンブラツクが工業的に最もすぐれた炭素粉末原
料である。
前記二酸化珪素と炭素粉末との使用原料混合比
はいずれかの原料が極端に多いときは未反応の原
料が炭化珪素中に混入することになるので、そろ
分離が難しく、結果的に不純物を含む炭化珪素と
なる。従つて一般に一方の原料成分を極端に多く
使用する態様はさけるのが好ましい。工業的には
二酸化珪素と炭素粉末との混合比が１：0.55〜
2.0好ましくは１：0.6〜1.0の範囲から選んで決定
すればよい。
本発明の炭化珪素を得る反応に於いては反応系
にアルミニウム又はアルミナ、硝酸アルミニウ
ム、硫酸アルミニウム等のアルミニウム化合物を
存在させることが必要である。該アルミニウム又
はアルミニウム化合物が反応系にない場合は目的
の2H型炭化珪素を多量に生成さすことは出来ず、
40容量％よりはるかに少量の2H型炭化珪素の生
成にとどまる。本発明の如く、炭化珪素中の2H
型炭化珪素を60容量％以上とするためには反応系
にアルミニウム又はアルミニウム化合物が存在し
ていることが必要である。しかし該アルミニウム
又はアルミニウム化合物は目的物の成分ではな
く、触媒的に2H型炭化珪素の生成に寄与するも
のであるから、多量に使用すると目的物中に不純
物として残存し、実質的に炭化珪素から分離する
ことは出来ない。従つて本発明の炭化珪素の製造
にあつては反応条件によつて異なるが一般に原料
の二酸化珪素に対してアルミニウムとして３重量
％以下の使用が好適である。工業的には二酸化珪
素に対してアルミニウムとして0.01〜２重量％の
範囲から選べば十分である。
本発明の炭化珪素を得る反応は前記のような要
件の他に窒素ガス雰囲気下又は窒素ガスを含む非
酸化性雰囲気下例えば窒素とアルゴン、ネオン、
ヘリウム等との混合ガス下に実施する必要があ
る。該窒素ガス量は前記したように得られる炭化
珪素中に含まれる窒素含有量に相当する量を最低
存在させる必要がある。しかしながら窒化珪素が
生成する原因となるような窒素ガスの使用はさけ
るのが好ましい。該窒化珪素が生成する原因は窒
素使用量だけでなく、反応装置型式、反応条件、
使用原料の種類等の差異により異なり一概に限定
することは出来ない。従つて他の条件に応じて窒
素ガスの使用量を予め実験室的に窒化珪素が生成
しないように決定して使用するのが好ましい。上
記実験室的な決定は容易に実施することが出来る
ものである。通常使用される量の基準は一般にバ
ツチ反応の場合は前記得られる炭化珪素中に含ま
れる窒素ガス量より５〜６％程度多くすればよ
く、窒素ガスを流通方式例えば筒状体の中間に加
熱炉を設け、該加熱炉に窒素ガスを流し込む方式
を採用する場合は外気が加熱炉に流入しないよう
に外気に対してわずかに加圧状態となるようにし
てもよい。
本発明の炭化珪素を製造する反応条件中、反応
温度は最も重要な要件となる。即ち前記のような
反応系で二酸化珪素と炭素粉末とを反応させて
2H型炭化珪素を多量に生成させるためには反応
温度が1550℃以上好ましくは1575℃以上更に好ま
しくは1600℃以上の温度を選ぶのが好ましい。ま
た反応温度があまりに高すぎると生成した2H型
炭化珪素がα型炭化珪素に移行するので、あまり
に高い温度を選ぶべきではない。しかし該α型炭
化珪素への移行する温度は前記反応系の反応条
件、原料組成、原料種類等によつて多少異なり一
概に限定することが出来ない。一般には1850℃以
下好ましくは1825℃以下更に好ましくは1800℃以
下を基準とし、予め実験室的に好適な温度を決定
するとよい。また反応時間は特に限定的ではなく
一般に30分〜10時間の範囲から選べばよい。
前記説明で明らかなように本発明の炭化珪素の
製造方法は二酸化珪素と炭素紛末とをアルミニウ
ム又はアルミニウム化合物が存在し且つ窒素ガス
又は窒素ガスを含む非酸化性雰囲気下に特定の温
度で反応させるものであるが該アルミニウム又は
アルミニウム化合物は必ずしも二酸化珪素及び炭
素粉末と別々に使用する必要はない。本発明の上
記製造方法で必要とするアルミニウムの量は少量
であるため、しばしば二酸化珪素の製造時に原料
に伴つて含まれるアルミニウム含有二酸化珪素が
二酸化珪素源とアルミニウム源を兼ねる原料とし
て好適に使用される。
本発明の前記製造方法により炭化珪素を製造す
る場合は後述する実施例でも明らかなように炭化
珪素中の70容量％或いはそれ以上の割合で2H型
炭化珪素を含む炭化珪素を得ることが出来る。し
かも上記2H型炭化珪素は従来1500℃以上では安
定性がないと考えられていたにもかかわらず1600
℃或いはそれ以上の反応温度で安定的に得られる
のである。これらの現象は従来の技術から推測す
ると全く驚異的な現象で、全く予想外の現象であ
る。
また本発明の2H型炭化珪素を60容量％以上含
みその余は主としてβ型炭化珪素よりなり且つ窒
素３重量％以下及び不可避的に含まれる小量成分
よりなる炭化珪素粉末は従来の炭化珪素に比べて
低温例えば100〜200℃低い温度で十分に焼結体を
得ることが出来るだけでなく高温時の強度が十分
に保持出来る炭化珪素である。従つて本発明が寄
与する分野は単にニユーセラミツク分野の材料に
とどまらず、種々の用途に利用される。
本発明を更に具体的に説明するため以下実施例
及び比較例を挙げて説明するが本発明はこれらの
実施例に限定されるものではない。
実施例 １
Na2O換算で１モル／の珪酸ソーダ溶液
（SiO2／Na2Oモル比2.0）500c.c.に0.5モル／の
塩化カルシウム溶液250c.c.を混合し、この混合液
をオートクレーブ中に密封して200℃、５Kg／cm2
の条件で20時間反応させた。冷却後濾過水洗、乾
燥し白色粉末を得た。この粉末は化学分析からほ
ぼ3Na2O・9CaO・32SiO2・25H2Oの組成であつ
た。また顕微鏡観察によると約5μの正方形状の
薄片であつた。この粉末を1N HCl中に投入し50
℃で２時間撹拌した。水洗濾過、乾燥した粉末は
約5μの正方形状の薄片から成るシリカであつた。
このシリカの不純物を分析した結果Al1.6重量％、
Ca0.03重量％、Fe0.002重量％であつた。
このシリカとカーボンブラツクを重量比で１：
１に混合したものを黒鉛るつぼに入れ内径60mmの
炉心管内に設置した。炉心管内に窒素ガスを毎分
20c.c.流した状態でるつぼを1700℃で５時間加熱し
た。加熱後、生成物中の過剰のカーボンを空気中
で650℃に加熱し除去した。得られた粉末の化学
分析値は炭素27.0重量％、窒素0.6重量％であつ
た。この粉末のＸ線回折図から得られた粉末は
2H型およびβ型の炭化珪素から成ることが同定
できたが、生成物中の2H型の含有率は窯業協会
誌87巻11号576頁（1979年）記載の方法に依つた。
即ちCuKα線によるＸ線回折図の2θ＝33.6゜のピー
クと2θ＝35.6゜のピーク強度を用いて
2H型の容量％＝100R／（１＋Ｒ）
β型の容量％＝100／（１＋Ｒ）
ここでＲ＝2.53I／（100−0.668I）であり、Ｉ
は2θ＝35.6°のピーク強度に対する2θ＝33.6゜のピ
ーク強度の比を100倍にした値である。この計算
式に基づいて、得られた粉末の組成を求めたとこ
ろ2H型＝79容量％、β型＝21容量％であつた。
また生成物中のアルミニウムは1.3重量％であつ
た。
実施例 ２
実施例１で用いたシリカおよびそれと同方法で
合成したAl含有量の異なるシリカを用い実施例
１と同様の実験を行つた。結果を第１表に示し
た。ここでNo.５、６、７は比較例である。
The present invention provides a silicon carbide powder containing a large amount of 2H type and a method for producing the same. For more information
The present invention relates to a high H-type silicon carbide powder consisting of 2H-type silicon carbide containing 60% by volume or more of 2H-type silicon carbide and β-type silicon carbide, and containing 3% by weight or less of nitrogen, and a method for producing the same. Conventionally, α-type and β-type silicon carbide are known as silicon carbide, and are excellent ceramics used for various purposes. However, these silicon carbides have the disadvantage of high sintering temperatures. For this reason, 2H type silicon carbide, which can be sintered at lower temperatures, has been expected.
However, even though the existence of 2H type silicon carbide is known, it is extremely difficult to produce powder with a high content, and no industrially superior technology has been established. For example, in JP-A No. 54-121298, silicon dioxide and carbon powder are reacted in the presence of a relatively large amount of aluminum under reduced pressure at a temperature of 1200 to 1500°C to produce a product rich in 2H type silicon carbide. A method for producing fine powder silicon carbide has been proposed. This method is an excellent method for obtaining powder containing a large amount of 2H type silicon carbide compared to conventional methods, but it does not eliminate the 2H type silicon carbide in the product.
It is difficult to reach 50%, and furthermore, it requires a reduced pressure operation, so it cannot necessarily be said that the method or powder is industrially satisfactory. Moreover, from a physical standpoint, the aluminum content often becomes high, which is not preferable. As a result of extensive research in order to solve the above technical problem, the present inventors found that
As a result of reacting silicon dioxide containing aluminum with carbon powder at the above temperature, the inventors discovered that silicon carbide powder containing a large amount of 2H type silicon carbide can be obtained, and have completed and proposed the present invention. That is, the method according to the present invention can easily produce 2H-type silicon carbide that is mainly composed of 2H-type silicon carbide and β-type silicon carbide, which contains 40% by volume or more of 2H-type silicon carbide, and contains 3% by weight or less of nitrogen. This makes it possible to obtain powder. in silicon carbide
If the 2H type content is less than 40% by volume, sinterability at relatively low temperatures, which is the objective of the present invention, cannot be achieved. If the 2H type is contained in an amount exceeding 50%, firing becomes relatively easy, but the strength of the obtained sintered body is somewhat insufficient. Products with a 2H type of over 60% by volume can be easily sintered and have sufficient strength. Therefore, the present invention contains 2H type silicon carbide in an amount of 60% by volume or more, and the remainder is mainly β.
type silicon carbide, and contains 3% by weight or less of nitrogen,
The present invention provides a high 2H type silicon carbide powder consisting of small amounts of other unavoidably included components. Further, the present invention provides silicon dioxide and carbon powder in the presence of aluminum or an aluminum compound and in a non-oxidizing atmosphere containing nitrogen gas or nitrogen gas at 1550 °C.
The present invention provides a method for producing high 2H type silicon carbide powder by reacting at a temperature of 0.degree. C. or higher. The silicon carbide of the present invention contains 60% by volume of 2H type silicon carbide.
Including the above, the rest is silicon carbide powder mainly consisting of β-type silicon carbide. Furthermore, the silicon carbide of the present invention contains 3% by weight or less of a nitrogen component resulting from its production. Silicon carbide containing 40% by volume or less of 2H type silicon carbide is known from several reports, for example as shown in the above-mentioned JP-A-54-121298 as part of the examples. However, the 2H type,
For example, industrially obtained silicon carbide powder containing 55% by volume or more is not known. Of course, 2H type silicon carbide itself is known, but it is impossible to obtain high 2H type silicon carbide powder by industrially concentrating 2H type from silicon carbide that contains 2H type at a low content rate. . Therefore, for example, a high
In order to obtain 2H type silicon carbide, it must be obtained as high 2H type silicon carbide during manufacturing. However, as in the present invention, 2H of 60% or more by volume
Conventionally, there was no known method for obtaining silicon carbide powder containing type silicon carbide. Moreover, in the present invention, due to the manufacturing process for high 2H type, the nitrogen content in the silicon carbide powder is generally 0.01% by weight or less.
Contained in the range of ~2.0% by weight. Such silicon carbide is new. At present, it is not necessarily clear in what form the above nitrogen is contained in the silicon carbide of the present invention, and how the above nitrogen affects the properties of the silicon carbide of the present invention. However, since the silicon carbide powder of the present invention has the following advantages when compared with conventionally known silicon carbide, it is presumed that these characteristics are strongly related to imparting these properties. That is, at 2000℃, 10
The sintered body obtained by hot pressing for a minute has a bending strength of 50 kg/mm 2 or more at 1500°C. This is because the conventional silicon carbide sintered body containing a relatively small amount of 2H type silicon carbide, for example, 40% by volume or less, has a high aluminum content and has an extremely low high temperature strength, making it unusable for practical use. It can be said that this is a huge improvement compared to not being able to obtain this. In addition, although it was known that conventional 2H type silicon carbide is stable at temperatures below 1500°C, β-type silicon carbide is generated at temperatures exceeding 1500°C, the 2H type silicon carbide of the present invention is stable at temperatures below 1500°C.
It does not substantially form at temperatures below .degree. C., and it forms stably at temperatures of 1,550.degree. C. or higher, preferably 1,575.degree. C. or higher, more preferably 1,600.degree. C. or higher, which should not be in the stable range. It is speculated that these differences are not simply due to the good purity of the silicon carbide of the present invention, but are also caused by the nitrogen component contained in the silicon carbide in some way. It is still not clear what form the nitrogen component contained in the silicon carbide of the present invention has. If the silicon carbide of the present invention is produced at a low temperature, for example, about 1500° C., the nitrogen content will be 30% by weight or more, which is clearly contained as silicon nitride (Si 3 N 4 ). However, when the reaction temperature becomes as high as 1550° C. or 1600° C., the nitrogen content becomes extremely low, and the presence of silicon nitride can no longer be confirmed even by X-ray diffraction. Although there is such a tendency, it can be inferred from the above advantages that the nitrogen contained is not contained as silicon nitride, but rather participates catalytically with aluminum in the formation of 2H-type silicon carbide in silicon carbide, or forms a reaction intermediate. It is presumed that it is directly incorporated into silicon carbide and is involved in high-temperature stability. However, the content of nitrogen components is preferably as small as possible in terms of purity of silicon carbide, and when obtaining silicon carbide for industrial use,
Aiming for 0.05-1.5% by weight may be suitable. As mentioned above, the silicon carbide of the present invention is a powder mainly composed of 2H type silicon carbide and β type silicon carbide in an amount of 60% by volume or more, but the aluminum used as a catalyst in the manufacturing method is a maximum of 4.0% by weight. may be included. However, the aluminum content may be 0.05% by weight or less depending on the manufacturing conditions when producing the silicon carbide of the present invention. Therefore, aluminum is unavoidably contained as an impurity during its production, and its content is preferably small as long as it does not adversely affect the production of 2H-type silicon carbide. When silicon carbide is obtained by the normal method described below, it is generally 0.01
It is often contained in the range of ~1.5% by weight. The silicon carbide of the present invention may have the composition as described above, and the manufacturing method thereof is not particularly limited. Typical methods that are generally suitable for production are as follows. One of the raw materials for producing the silicon carbide of the present invention is silicon dioxide. The silicon dioxide is not particularly limited, and known raw materials such as silicon nitride and silicon carbide can be used. Generally, amorphous silicon dioxide such as hydrated silicic acid, anhydrous silicic acid, etc. are preferably used. When using crystalline silicon dioxide such as quartz, it is necessary to use it in fine powder. Of course, the amorphous silicon dioxide is usually in the form of a powder, and may be used as it is or, in the case of agglomerated particles, mechanically redispersed to form, for example, 10 μm or less. Another raw material for producing the silicon carbide of the present invention is carbon powder. There is no particular limitation as long as the carbon is in powder form, and carbon of 10 μm or less is generally suitably employed. The particle size of the silicon carbide of the present invention tends to be influenced by the particle size of the carbon powder used. Therefore, if silicon carbide is to be obtained in powder form, it is necessary to use fine particles of carbon powder as a raw material or to use it after pulverizing it into fine particles. In general, carbon black is the industrially best raw material for carbon powder. When the mixing ratio of the raw materials used for silicon dioxide and carbon powder is extremely large, unreacted raw materials will be mixed into silicon carbide, making it difficult to separate them and resulting in impurities. It becomes silicon carbide. Therefore, it is generally preferable to avoid embodiments in which one raw material component is used in an extremely large amount. Industrially, the mixing ratio of silicon dioxide and carbon powder is 1:0.55~
2.0, preferably 1: may be selected from the range of 0.6 to 1.0. In the reaction for obtaining silicon carbide of the present invention, it is necessary to have aluminum or an aluminum compound such as alumina, aluminum nitrate, or aluminum sulfate present in the reaction system. If the aluminum or aluminum compound is not present in the reaction system, the desired 2H type silicon carbide cannot be produced in large quantities,
The production of 2H type silicon carbide remains at a much smaller amount than 40% by volume. As in the present invention, 2H in silicon carbide
In order to increase the content of type silicon carbide to 60% by volume or more, it is necessary that aluminum or an aluminum compound be present in the reaction system. However, the aluminum or aluminum compound is not a component of the target product, but rather contributes to the production of 2H-type silicon carbide in a catalytic manner, so if a large amount is used, it will remain as an impurity in the target product and will essentially remove the silicon carbide from the target product. cannot be separated. Therefore, in producing the silicon carbide of the present invention, it is generally preferable to use 3% by weight or less of aluminum based on the raw material silicon dioxide, although this varies depending on the reaction conditions. Industrially, it is sufficient to select from a range of 0.01 to 2% by weight of aluminum based on silicon dioxide. In addition to the above-mentioned requirements, the reaction for obtaining silicon carbide of the present invention is carried out under a nitrogen gas atmosphere or a non-oxidizing atmosphere containing nitrogen gas, such as nitrogen and argon, neon,
It is necessary to carry out the test under a mixed gas such as helium. The amount of nitrogen gas needs to be present at a minimum amount corresponding to the nitrogen content contained in the silicon carbide obtained as described above. However, it is preferable to avoid using nitrogen gas, which causes the formation of silicon nitride. The cause of the formation of silicon nitride is not only the amount of nitrogen used, but also the type of reactor, reaction conditions,
It varies depending on the type of raw materials used, etc., and cannot be definitively limited. Therefore, it is preferable to determine the amount of nitrogen gas to be used in advance in a laboratory according to other conditions so as not to generate silicon nitride. The above laboratory determinations can be easily carried out. Generally, in the case of a batch reaction, the standard for the amount usually used is about 5 to 6% greater than the amount of nitrogen gas contained in the obtained silicon carbide. When a furnace is provided and nitrogen gas is poured into the heating furnace, the outside air may be slightly pressurized so that the outside air does not flow into the heating furnace. Among the reaction conditions for producing silicon carbide of the present invention, the reaction temperature is the most important requirement. That is, silicon dioxide and carbon powder are reacted in the reaction system described above.
In order to produce a large amount of 2H type silicon carbide, it is preferable to select a reaction temperature of 1550°C or higher, preferably 1575°C or higher, and more preferably 1600°C or higher. Furthermore, if the reaction temperature is too high, the generated 2H type silicon carbide will transition to α type silicon carbide, so a temperature that is too high should not be chosen. However, the temperature at which the transition to α-type silicon carbide occurs varies somewhat depending on the reaction conditions of the reaction system, the raw material composition, the type of raw materials, etc., and cannot be absolutely limited. Generally, a suitable temperature should be determined in advance in a laboratory, with a standard of 1850°C or lower, preferably 1825°C or lower, and more preferably 1800°C or lower. Further, the reaction time is not particularly limited and may generally be selected from the range of 30 minutes to 10 hours. As is clear from the above description, the method for producing silicon carbide of the present invention involves reacting silicon dioxide and carbon powder at a specific temperature in the presence of aluminum or an aluminum compound and in nitrogen gas or a non-oxidizing atmosphere containing nitrogen gas. However, the aluminum or aluminum compound does not necessarily need to be used separately from the silicon dioxide and carbon powder. Since the amount of aluminum required in the above production method of the present invention is small, aluminum-containing silicon dioxide, which is often included in raw materials during the production of silicon dioxide, is preferably used as a raw material that serves as both a silicon dioxide source and an aluminum source. Ru. When silicon carbide is produced by the production method of the present invention, it is possible to obtain silicon carbide containing 2H type silicon carbide in a proportion of 70% by volume or more in silicon carbide, as is clear from the examples described later. Furthermore, although the 2H type silicon carbide mentioned above was previously thought to be unstable at temperatures above 1500℃,
It can be stably obtained at reaction temperatures of °C or higher. These phenomena are completely surprising and completely unexpected when estimated from conventional technology. In addition, the silicon carbide powder of the present invention, which contains 60% by volume or more of 2H type silicon carbide, the rest mainly consists of β-type silicon carbide, and has 3% by weight or less of nitrogen and a small amount of unavoidably contained components, is different from conventional silicon carbide. Silicon carbide is a silicon carbide that not only can be sufficiently sintered at a lower temperature, for example, 100 to 200°C, but also can maintain sufficient strength at high temperatures. Therefore, the field to which the present invention contributes is not limited to materials in the field of new ceramics, but is utilized for various purposes. EXAMPLES In order to explain the present invention more specifically, Examples and Comparative Examples will be described below, but the present invention is not limited to these Examples. Example 1 500 c.c. of 1 mol/silicate sodium silicate solution (SiO 2 /Na 2 O molar ratio 2.0) in terms of Na 2 O was mixed with 250 c.c. of 0.5 mol/calcium chloride solution. Seal in autoclave at 200℃, 5Kg/cm 2
The reaction was carried out under these conditions for 20 hours. After cooling, the mixture was filtered, washed with water, and dried to obtain a white powder. Chemical analysis revealed that this powder had a composition of approximately 3Na 2 O.9CaO.32SiO 2.25H 2 O. Furthermore, microscopic observation revealed that it was a square-shaped flake of about 5 μm. Pour this powder into 1N HCl and
Stirred at ℃ for 2 hours. The powder that was washed with water, filtered, and dried was silica consisting of square flakes of about 5 microns.
Analysis of impurities in this silica revealed Al1.6% by weight.
The content was 0.03% by weight of Ca and 0.002% by weight of Fe. The weight ratio of this silica and carbon black is 1:
The mixture of 1 and 1 was placed in a graphite crucible and placed in a furnace tube with an inner diameter of 60 mm. Nitrogen gas is introduced into the reactor core tube every minute.
The crucible was heated at 1700° C. for 5 hours with 20 c.c. flowing. After heating, excess carbon in the product was removed by heating to 650°C in air. The chemical analysis values of the obtained powder were 27.0% by weight of carbon and 0.6% by weight of nitrogen. The powder obtained from the X-ray diffraction pattern of this powder is
Although it was identified that the product was composed of 2H type and β type silicon carbide, the content of 2H type in the product was determined by the method described in Ceramics Association Journal, Vol. 87, No. 11, p. 576 (1979).
That is, using the peak at 2θ = 33.6° and the peak intensity at 2θ = 35.6° in the X-ray diffraction diagram of CuKα rays, 2H type capacity % = 100R / (1 + R) β type capacity % = 100 / (1 + R) Here, R=2.53I/(100−0.668I), and I
is the value obtained by multiplying the ratio of the peak intensity at 2θ=33.6° to the peak intensity at 2θ=35.6° by 100 times. Based on this calculation formula, the composition of the obtained powder was found to be 2H type = 79% by volume and β type = 21% by volume.
The aluminum content in the product was 1.3% by weight. Example 2 The same experiment as in Example 1 was conducted using the silica used in Example 1 and silica with different Al contents synthesized by the same method. The results are shown in Table 1. Here, Nos. 5, 6, and 7 are comparative examples.
【表】
実施例 ３
四塩化珪素を加水分解して得た無水シリカ（商
品名アエロジル）とカーボンブラツクおよびアル
ミナ（純度99.9％、平均粒径0.7μｍ）を重量比で
１：0.7：（第２表に示す）の割合で均一に混合し
たものを黒鉛るつぼに入れ内径60mmの炉心管内に
設置した。炉心管に窒素ガスを毎分50c.c.流した状
態でるつぼを1700℃で５時間加熱した。生成物中
の過剰のカーボンは空気中650℃で酸化除去した。
得られた粉末の化学分析値はまた粉末Ｘ線回折の
結果から得た2H型の容量％、窒素及びアルミニ
ウム含量を夫々第２表に示す。ここでNo.１、４及
び５は比較例である。[Table] Example 3 Anhydrous silica (trade name Aerosil) obtained by hydrolyzing silicon tetrachloride, carbon black and alumina (purity 99.9%, average particle size 0.7 μm) were mixed in a weight ratio of 1:0.7: (secondary (shown in the table) was mixed uniformly in a graphite crucible and placed in a furnace tube with an inner diameter of 60 mm. The crucible was heated at 1700° C. for 5 hours with nitrogen gas flowing through the furnace tube at 50 c.c./min. Excess carbon in the product was removed by oxidation at 650°C in air.
The chemical analysis values of the obtained powder are also shown in Table 2, including the volume % of 2H type, nitrogen and aluminum content, respectively, obtained from the powder X-ray diffraction results. Here, Nos. 1, 4, and 5 are comparative examples.
【表】
参考例 １
実施例１で得られた2H型炭化珪素を79容量％、
β型炭化珪素を21容量％で構成される炭化珪素粉
末を80℃でフツ酸処理し、シリカ分を除去し、水
洗、乾燥した。この粉末にホウ素１％、炭素１％
を加えて、よく混合したもの（14ｇ）を内径40mm
の黒鉛型に入れ、200Kg／cm2、2000℃、10分の条
件でアルゴン気流中でホツトプレスした。得られ
た燃結体の密度は3.17ｇ／cm3であつた。この焼結
体を切断、研磨して厚さ約３mm、幅約４mmの試料
とした。この試料の高温曲げ強度をスパン20mm、
クロスヘツドスピード0.5mm／minの条件で1500
℃、アルゴン雰囲気で測定したところ４本の試料
の平均値で63Kg／mm2であつた。
参考例 ２
実施例３で得られた各種の炭化珪素を用いて参
考例１と同様にして高温曲げ強度を測定した。そ
の結果を第３表に示す。[Table] Reference example 1 79% by volume of the 2H type silicon carbide obtained in Example 1,
Silicon carbide powder composed of 21% by volume of β-type silicon carbide was treated with hydrofluoric acid at 80°C to remove silica, washed with water, and dried. This powder contains 1% boron and 1% carbon.
Add and mix well (14g) to an inner diameter of 40mm.
It was placed in a graphite mold and hot pressed in an argon stream at 200 kg/cm 2 , 2000° C., and 10 minutes. The density of the obtained combusted body was 3.17 g/cm 3 . This sintered body was cut and polished to obtain a sample with a thickness of about 3 mm and a width of about 4 mm. The high-temperature bending strength of this sample is measured with a span of 20 mm.
1500 at crosshead speed 0.5mm/min
℃ in an argon atmosphere, the average value of four samples was 63 Kg/mm 2 . Reference Example 2 Using various silicon carbide obtained in Example 3, high temperature bending strength was measured in the same manner as in Reference Example 1. The results are shown in Table 3.
【表】
尚No.１、４及び５は、比較例による炭化珪素を
使用した例である。[Table] Nos. 1, 4 and 5 are comparative examples using silicon carbide.
Claims (1)
は、主としてβ型炭化珪素よりなり、且つ窒素３
重量％以下とその他不可避的に含まれる小量成分
とよりなる高2H型炭化珪素粉末。 ２ 二酸化珪素と炭素粉末とを、アルミニウム又
はアルミニウム化合物が存在し且つ窒素ガス又は
窒素ガスを含む非酸化性雰囲気下に1550℃以上の
温度で反応させることを特徴とする2H型炭化珪
素を60容量％以上含む粉末の製造方法。 ３ 二酸化珪素と炭素粉末との原料混合比が１：
0.55〜１：2.0の範囲である特許請求の範囲２記
載の方法。 ４ アルミニウム又はアルミニウム化合物が二酸
化珪素に対してアルミニウムとして３重量％以下
存在する特許請求の範囲２記載の方法。[Claims] 1 Contains 60% by volume or more of 2H type silicon carbide, the remainder mainly consists of β type silicon carbide, and nitrogen 3
High 2H type silicon carbide powder consisting of less than % by weight and other unavoidably small amounts of components. 2 60 volumes of 2H type silicon carbide produced by reacting silicon dioxide and carbon powder at a temperature of 1550°C or higher in the presence of aluminum or an aluminum compound and in a non-oxidizing atmosphere containing nitrogen gas or nitrogen gas. % or more. 3 The raw material mixing ratio of silicon dioxide and carbon powder is 1:
The method according to claim 2, wherein the ratio is in the range of 0.55 to 1:2.0. 4. The method according to claim 2, wherein the aluminum or aluminum compound is present in an amount of 3% by weight or less as aluminum based on silicon dioxide.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56144758A JPS5849611A (en) | 1981-09-16 | 1981-09-16 | Powder containing 2h type silicon carbide and its preparation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56144758A JPS5849611A (en) | 1981-09-16 | 1981-09-16 | Powder containing 2h type silicon carbide and its preparation |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5849611A JPS5849611A (en) | 1983-03-23 |
| JPH0151443B2 true JPH0151443B2 (en) | 1989-11-02 |
Family
ID=15369706
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP56144758A Granted JPS5849611A (en) | 1981-09-16 | 1981-09-16 | Powder containing 2h type silicon carbide and its preparation |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5849611A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60191014A (en) * | 1984-03-10 | 1985-09-28 | Denki Kagaku Kogyo Kk | Manufacture of 2h type silicon carbide having low aluminum content |
| JPS6230662A (en) * | 1985-07-30 | 1987-02-09 | 大同特殊鋼株式会社 | Raw material powder for silicon carbide base sintered body and manufacture |
| US4756895A (en) * | 1986-08-22 | 1988-07-12 | Stemcor Corporation | Hexagonal silicon carbide platelets and preforms and methods for making and using same |
| US4981665A (en) * | 1986-08-22 | 1991-01-01 | Stemcor Corporation | Hexagonal silicon carbide platelets and preforms and methods for making and using same |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54121298A (en) * | 1978-03-15 | 1979-09-20 | Hiroshige Suzuki | Impalpable powdery silicon carbide enriched with 2h type silicon carbide and its manufacture |
| JPS5759208A (en) * | 1980-09-26 | 1982-04-09 | Shinko Electric Co Ltd | Calling system for unmanned and guided vehicle |
-
1981
- 1981-09-16 JP JP56144758A patent/JPS5849611A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5849611A (en) | 1983-03-23 |
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