JP3550919B2 - Nitrogen-containing silane compounds - Google Patents
Nitrogen-containing silane compounds Download PDFInfo
- Publication number
- JP3550919B2 JP3550919B2 JP32932496A JP32932496A JP3550919B2 JP 3550919 B2 JP3550919 B2 JP 3550919B2 JP 32932496 A JP32932496 A JP 32932496A JP 32932496 A JP32932496 A JP 32932496A JP 3550919 B2 JP3550919 B2 JP 3550919B2
- Authority
- JP
- Japan
- Prior art keywords
- nitrogen
- containing silane
- silane compound
- silicon nitride
- less
- 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 - Lifetime
Links
Description
【０００１】
【発明の属する技術分野】
本発明は、新規な含窒素シラン化合物に関するものであり、詳しくは、構造用セラミックスとして使用される窒化ケイ素セラミックスの中で、特に高強度高靱性の窒化ケイ素セラミックスを製造するための出発原料として好適な含窒素シラン化合物に関するものである。
【０００２】
【従来の技術及びその問題点】
窒化ケイ素セラミックスは、高強度、高靭性、高耐蝕性という優れた特性を有し、１０００℃以下の温度で使用される構造材料や機械部品として種々の分野への用途展開が進展している。
この窒化ケイ素の焼結においては、通常Ｙ２Ｏ３、Ａｌ２Ｏ３等の酸化物を５〜１０重量％程度添加して焼結を行う為、焼結条件により、得られる焼結体の機械的特性が変化するという難点があった。このような焼結条件の変動による機械的特性の変化を防止し、焼結条件によらず安定して優れた機械的特性を発現し得る窒化ケイ素セラミックスを製造する為に、Ｙ２Ｏ３、ＭｇＯ、Ｓｃ２Ｏ３等の焼結助剤の探索やＣｒ２Ｎ、ＮｂＢ、ＴａＳｉ２、ＺｒＳｉ２等の硬質粒子の分散の検討と併行し、焼結体製造原料である窒化ケイ素粉末の製造条件についても研究が行われている。
【０００３】
従来、窒化ケイ素粉末の製法として、ハロゲン化ケイ素とアンモニアとを反応させるイミド分解法が知られており、この方法で製造された窒化ケイ素粉末は、易焼結性であり、かつ優れた焼結体性能を示すと言われている。
そこで、イミド分解法の出発原料である含窒素シラン化合物の粉末特性と得られる窒化ケイ素粉末の焼結性及び焼結体特性との関係について詳細に検討した結果、特定の粉末特性を有する含窒素シラン化合物を用いた場合に、得られる窒化ケイ素粉末を通常の焼結条件で焼結することで、優れた機械的特性を有する窒化ケイ素セラミックスを再現性良く安定的に製造することができることを見出した。
【０００４】
【発明の目的】
本発明の目的は、優れた機械的特性を有する窒化ケイ素セラミックスを再現性良く安定して製造できる窒化ケイ素粉末を製造するための出発原料となる含窒素シラン化合物を提供することにある。
【０００５】
【課題を解決するための手段】
本発明は、真密度が１．４〜１．９ｇ／ｃｍ３、軽装密度が０．０４５〜０．０９０ｇ／ｃｍ３であり、かつ比表面積が６００〜１０００ｍ２／ｇ、酸素含有量が３．５重量％以下、炭素含有量が０．２５重量％未満である主としてシリコンジイミドからなる含窒素シラン化合物に関するものである。
本発明の含窒素シラン化合物は、主として化学式 Ｓｉ（ＮＨ）２ で表されるシリコンジイミドからなるものである。含窒素シラン化合物の窒素含有量は、４５．５〜５１．５重量％、ケイ素含有量は、４４．５〜５１．５重量％である。
【０００６】
シリコンジイミドは、ケイ素原子と窒素原子が三次元のネットワーク構造を形成しているので、そのＳｉ−Ｎ結合の規則性により真密度が変わってくる。
本発明の含窒素シラン化合物は、真密度が１．４〜１．９ｇ／ｃｍ３、好ましくは、１．５〜１．７ｇ／ｃｍ３である。真密度が１．４ｇ／ｃｍ３よりも小さくなると、これを焼成した際に、結晶化が高温側にシフトし、針状晶が生成しやすくなる。針状晶の割合が増えると、得られる焼結体の強度特性が低下し、またバラツキも増大して、焼結体の信頼性が悪化する。さらに、焼結体の耐酸化性も悪化し、酸化増量の上昇、酸化後強度の低下を引き起こす。また、真密度が１．９ｇ／ｃｍ３よりも大きくなると、これを焼成した際に、結晶化が低温側にシフトし、角ばった安定した粒状粒子が生成する。しかしながら、過度に安定化された粒子は焼結活性が低く、焼結体を作製する際に緻密化させることが難しくなるので好ましくない。
【０００７】
また、軽装密度は０．０４５〜０．０９０ｇ／ｃｍ３、好ましくは、０．０５５〜０．０８５ｇ／ｃｍ３である。軽装密度が０．０４５ｇ／ｃｍ３よりも小さくなると、これを焼成して得られる窒化ケイ素粉末のβ分率が低下すると共に、粉末の凝集が強くなる。その結果、湿式ボールミル等により焼結助剤と混合する際に、助剤を均一に分散し難くなる。窒化ケイ素粉末のβ分率には最適値があり、過度に低いβ分率は好ましくない。また、助剤との均一混合が難しくなる影響として、焼結体の室温強度及び高温強度が低下してしまうという問題がある。また、軽装密度が０．０９０ｇ／ｃｍ３よりも大きくなると、これを焼成して得られる窒化ケイ素粉末のβ分率が上昇すると共に、粉末の凝集が弱くなって解砕しやすくなる。このため、湿式ボールミル等により焼結助剤と混合する際に、助剤を均一に分散できる。しかしながら、成形体のプレス密度が低下し、焼結体の破壊靱性が低下するいう問題を生じるので好ましくない。
【０００８】
比表面積は６００〜１０００ｍ２／ｇ、好ましくは、７００〜８００ｍ２／ｇである。比表面積が６００ｍ２／ｇよりも小さくなると、これを焼成して得られる粉末の凝集指標が大きくなり、最終的に得られる焼結体の高温強度が低下する。また、１０００ｍ２／ｇよりも大きくなると、窒化ケイ素粉末のα分率が低下して焼結性が悪くなるので好ましくない。
また、酸素含有量は３．５重量％以下、好ましくは、２．５重量％以下である。酸素含有量が、３．５重量％よりも多くなると、得られる窒化ケイ素粉末の焼結性は良好であるものの、得られる焼結体の高温強度が低下する。また、得られる窒化ケイ素粉末の内部酸素量が多くなるため、得られる焼結体の酸化後強度が低下する。
さらに、含窒素シラン化合物を製造する際に、原料又は反応溶媒から炭素含有物質（例えば、トルエン）が不純物として混入してくるが、その含有量は炭素換算で０．２５重量％未満、好ましくは、０．１０重量％未満である。炭素含有量が０．２５重量％以上になると、含窒素シラン化合物を焼成して得られる窒化ケイ素粉末の炭素含有量が０．１０重量％よりも多くなり、その結果、焼結性が悪くなるので好ましくない。
【０００９】
さらに、本発明の含窒素シラン化合物は、平均粒径、金属不純物含有量、ハロゲン含有量が以下の範囲にあることが、所期の目的を達成する上で望ましい。
平均粒径は１００ｎｍ以下であることが望ましい。平均粒径が１００ｎｍよりも大きくなると、これを焼成した際に、針状晶が生成しやすくなる。針状晶の割合が増えると、得られる焼結体の強度特性が低下し、またバラツキも増大して、焼結体の信頼性が悪化する。さらに、焼結体の耐酸化性も悪化し、酸化増量の上昇、酸化後強度の低下を引き起こす。
また、金属不純物は、そのまま焼成粉末中に残存してしまうが、金属不純物は、焼結体の破壊発生源となるため、高信頼性の焼結体を作製するには、金属不純物を低減しなければならない。本発明においては、金属不純物含有量は１００ｐｐｍ以下であることが望ましい。金属不純物含有量が１００ｐｐｍよりも多くなると、得られる焼結体の強度が低下する。さらに、得られる焼結体の粒界の組成変化、粒界での不純物偏析が起こり、焼結体の耐酸化性が悪化し、酸化増量の上昇、酸化後強度の低下が起こる。
ハロゲン含有量は１８０ｐｐｍ以下であることが望ましい。含窒素シラン化合物に含まれるハロゲンの約半分は、焼成粉末中に残留する。窒化ケイ素粉末中に含まれるハロゲンは、焼結体の粒界相に集まり、粒界相の軟化温度を下げる作用がある。このため、ハロゲン含有量が１８０ｐｐｍよりも多くなると、最終的に得られる焼結体の高温強度が低下し、また、耐酸化性も悪化する。
【００１０】
本発明の含窒素シラン化合物を製造する方法は、上記特性を有する含窒素シラン化合物が得られれば、特に制限はないが、例えば、以下に示すように、ハロゲン化シランと液体アンモニアとを反応させることにより製造することができる。即ち、液体アンモニアと、液体アンモニアと溶けあわずかつ比重が液体アンモニアより大きい有機溶媒とが比重差により二層に分離している反応系の下部有機溶媒層中に、ハロゲン化シランと前記有機溶媒との混合溶液を供給することによって、ハロゲン化シランと液体アンモニアとを反応させる。そして、前記反応で生成した含窒素シラン化合物を液体アンモニアで洗浄し、副生したハロゲン化アンモニウムを除去する。
【００１１】
上記反応において、圧力を０．５４〜１３．６気圧、反応温度を−４５〜３６℃の範囲に設定することにより、真密度が１．４〜１．９ｇ／ｃｍ３の範囲の含窒素シラン化合物を合成することができる。また、圧力を１．５〜７．２気圧、反応温度を−２５〜１５℃の範囲とすることにより、真密度を１．５〜１．７ｇ／ｃｍ３の範囲に制御することができる。
また、生成した含窒素シラン化合物をジャケット式撹拌槽等を用いて乾燥する際の乾燥時間と攪拌回転数を変えることにより、含窒素シラン化合物の軽装密度を０．０４５〜０．０９０ｇ／ｃｍ３の範囲に制御することができる。乾燥条件と軽装密度との関係は、用いる乾燥機により変わってくるので、予め両者の関係式を調べて適宜条件を設定すればよい。
【００１２】
さらに、反応の際のハロゲン化シランと液体アンモニアとの比率（体積基準）を０．０３０〜０．０４７、好ましくは、０．０３５〜０．０４１の範囲で変化させることにより、比表面積６００〜１０００ｍ２／ｇ、好ましくは、７００〜８００ｍ２／ｇの含窒素シラン化合物を合成することができる。
なお、前記反応の初期段階では、液体アンモニアは大過剰に存在するが、反応の進行によりアンモニアが消費されるため、液体アンモニアも連続的に反応槽へ供給することになる。そして、定常状態において反応槽内へ供給するハロゲン化シランと液体アンモニアとの体積比率を変化させる。
また、上記反応で得られた含窒素シラン化合物を洗浄する際に使用する液体アンモニア中の水分量をできるだけ少なくすることで、含窒素シラン化合物の酸素含有量を３．５重量％以下、好ましくは、２．５重量％以下とすることができる。
具体的には、液体アンモニア中の水分量Ｈ（ｐｐｍ）と洗浄液量／含窒素シラン化合物量Ｗ（ｌ／ｋｇ）との積（Ｈ×Ｗ）が、３１５００以下、好ましくは、２２５００以下とする。
同様に、含窒素シラン化合物を洗浄する際に使用する液体アンモニア中の有機化合物の含有量を１５００ｐｐｍ以下、好ましくは、６００ｐｐｍ以下とすることにより、含窒素シラン化合物の炭素含有量を０．２５重量％未満、好ましくは、０．１０重量％未満とすることができる。
【００１３】
含窒素シラン化合物の平均粒径は、反応槽の温度と反応槽へ供給するハロゲン化シランと希釈用の有機溶媒との混合比率（体積比率）との両方を制御することで変化させることができる。含窒素シラン化合物の平均粒径を１００ｎｍ以下にするには、混合比率を０．０８以上とすればよい。
金属不純物は、反応槽、洗浄槽、乾燥機等の内部に設置された撹拌翼の摺動摩耗、接触摩耗により混入するものであり、機器の調整、制御精度の改善により低減することができる。具体的には、撹拌翼と各種の金属部品（ろ過板、容器壁など）との間隔を５ｍｍ以上、好ましくは、１０ｍｍ以上空け、なおかつ、回転翼先端部における最大周速を５ｍ／ｓ以下に制御することにより、金属不純物量を１００ｐｐｍ以下にすることができる。
ハロゲン含有量は、反応で得られた含窒素シラン化合物とハロゲン化アンモニウムとの混合物からハロゲン化アンモニウムを洗浄、除去する際に使用する液体アンモニアの量によって変化する。通常、液体アンモニアを含窒素シラン化合物１ｋｇ当たり４０ｌ以上使用することにより、ハロゲン含有量を１８０ｐｐｍ以下にすることができる。ハロゲン含有量は、多量の液体アンモニアの使用により、いくらでも低減できるが、過度の洗浄はコストアップにつながるので経済的でない。
【００１４】
前記反応で使用するハロゲン化シランとしては、ＳｉＦ４、Ｈ２ＳｉＦ６、ＨＳｉＦ３、Ｈ３ＳｉＦ５、Ｈ３ＳｉＦ、Ｈ５ＳｉＦ３等の弗化シラン、ＳｉＣｌ４、ＨＳｉＣｌ３、Ｈ２ＳｉＣｌ２、Ｈ３ＳｉＣｌ等のクロルシラン、ＳｉＢｒ４、ＨＳｉＢｒ３、Ｈ２ＳｉＢｒ２、Ｈ３ＳｉＢｒ、等のブロモシラン、及びＳｉＩ４、ＨＳｉＩ３、Ｈ２ＳｉＩ２、Ｈ３ＳｉＩ等のヨウ化シランを使用することができる。また、ＲＳｉＸ３、Ｒ２ＳｉＸ２、Ｒ３ＳｉＸ（ＲはＣＨ３、Ｃ２Ｈ５、Ｃ３Ｈ７等のアルキル基、Ｘはハロゲン）等のハロゲン化アルキルシランも使用することができる。
【００１５】
また、有機溶媒としては、液体アンモニアやハロゲン化シランに対して不活性であるとともに、反応温度で液体アンモニアと溶けあわず、かつ比重が液体アンモニアより大きいものが用いられる。例えば、ｎ−ヘプタン、ｎ−ヘキサン、ｎ−ペンタン、Ｃ−ヘキサン等の炭化水素数５〜７の脂肪族炭化水素、ベンゼン、トルエン、キシレン等の芳香族炭化水素などの単独または混合物が挙げられる。
【００１６】
本発明の含窒素シラン化合物を出発原料として用いることにより、優れた機械的特性を有する窒化ケイ素セラミックスを再現性良く安定して製造できる窒化ケイ素粉末を製造することができる。
まず、含窒素シラン化合物を酸素含有量５％以下の窒素あるいはアンモニア含有不活性ガス雰囲気下に６００〜１２００℃の範囲の温度で仮焼して非晶質窒化ケイ素粉末を製造する。
このとき、含窒素シラン化合物は、室温から徐々に分解していき、２５０〜６００℃で特に激しく分解してアンモニアを発生する。
窒素あるいはアンモニア含有不活性ガスとしては、窒素またはアンモニア、あるいはさらにアルゴン、ヘリウム等との混合ガスが挙げられる。
【００１７】
次に、得られた非晶質窒化ケイ素粉末を窒素あるいはアンモニア含有不活性ガス雰囲気下に焼成して結晶質窒化ケイ素粉末を製造する。
焼成温度は１４００〜１６００℃の範囲である。焼成温度が１４００℃より低いと、窒化ケイ素の結晶化が十分に進行しない。また、焼成温度が１６００℃を越えると、粗大結晶から成る結晶質窒化ケイ素粉末が生成し易いので好ましくない。また、急激な昇温は粒子形状を均一にする上で好ましくなく、１１５０〜１４００℃の範囲を１．５時間以上かけてゆっくり昇温することが望ましい。
【００１８】
含窒素シラン化合物及び非晶質窒化ケイ素粉末の加熱に使用される加熱炉としては、高周波誘導加熱方式または抵抗加熱方式によるバッチ式電気炉、プッシャー炉、ロータリーキルン炉、シャフトキルン炉、流動化焼成炉等が用いられる。特に連続焼成炉は非晶質窒化ケイ素の結晶化反応に伴う発熱の効率的な放散に対して、有効な手段である。
【００１９】
得られた窒化ケイ素粉末は、従来の窒化ケイ素粉末の場合と同様な方法、例えば、酸化アルミニウム、酸化イットリウム、酸化マグネシウム等の焼結助剤と混合し、混合物を所定の形状に成形した後、焼結することにより、窒化ケイ素セラミックス（焼結体）を製造することができる。上記成形圧力は、０．５〜５ｔｏｎ／ｃｍ２程度とすれば良く、また上記焼結条件は、焼結温度１５００〜２０００℃、雰囲気圧力０．５〜１００気圧、焼結時間１〜１０時間程度とすれば良い。
【００２０】
この窒化ケイ素粉末を用いて製造された窒化ケイ素セラミックス（焼結体）は、従来のものと比較して、高強度、高靱性、高ワイブル係数であるばかりでなく、耐酸化性にも優れていることから、１４００℃以下の温度で使用されるターボローター、バルブ、ディーゼルエンジン副燃焼室等の熱機関用構造材料や機械部品として用いられる窒化ケイ素セラミックスの製造用原料として特に好適なものである。
【００２１】
【実施例】
以下に本発明の実施例を比較例と共に挙げ、本発明を更に詳しく説明する。
実施例１〜１４及び比較例１〜８
〔含窒素シラン化合物の製造〕
〔表１〕に示す温度及び圧力下に、直径３０ｃｍ、高さ４５ｃｍの縦型反応槽内の空気を窒素ガスで置換した後、液体アンモニア及びトルエンを仕込んだ。反応槽内では、上層の液体アンモニアと下層のトルエンとに分離した。〔表１〕に示す割合で調製した四塩化ケイ素とトルエンよりなる溶液を、導管を通じて、ゆっくり撹拌されている下層に供給した。トルエン溶液の供給と共に、上下層の界面近傍に白色の反応生成物が析出した。
反応終了後、反応液を濾過槽へ移送し、生成物を濾別して、液体アンモニアで洗浄し、主としてシリコンジイミドからなる含窒素シラン化合物を得た。
【００２２】
上記反応において、真密度は反応温度を変化させて制御した。
また、軽装密度は、生成した含窒素シラン化合物をジャケット式撹拌槽（４５度傾斜２枚羽根パドル付）を用いて加熱蒸気で乾燥する際の乾燥時間と攪拌回転数を変えて制御した。乾燥時間は、溶媒が飛びきったら温度が上がり始めるので、粉体層の温度が上がり始める時点を乾燥の終点とした。
比表面積は、反応の際の四塩化ケイ素と液体アンモニアとの比率（体積基準）を変化させることにより、制御した。なお、前記反応の初期段階では、液体アンモニアは大過剰に存在するが、反応の進行によりアンモニアが消費されるため、液体アンモニアも連続的に反応槽へ供給することになる。そして、定常状態において反応槽内へ供給する四塩化ケイ素と液体アンモニアとの体積比率を〔表１〕に示す範囲で変化させることにより、種々の比表面積の含窒素シラン化合物を合成した。
【００２３】
酸素含有量は、生成した含窒素シラン化合物を洗浄する際に使用する液体アンモニア中の水分量を〔表１〕に示す範囲で変化させて制御した。
同様に、炭素含有量は、含窒素シラン化合物を洗浄する際に使用する液体アンモニア中のトルエン含有量を〔表１〕に示す範囲で変化させて制御した。
また、平均粒径は、反応槽の温度と反応槽へ供給する四塩化ケイ素とトルエンとの体積比率を〔表１〕に示す範囲で変化させて制御した。
塩素含有量は、含窒素シラン化合物を洗浄する際に使用する液体アンモニアの使用液量を〔表１〕に示す範囲で変化させて制御した。
金属不純物は、撹拌翼の調整状態により変化した。
【００２４】
【表１】
得られた含窒素シラン化合物の粉末特性を〔表２〕に示す。
含窒素シラン化合物の真密度は、媒液として脱水処理したキシレンを使用し、ピクノメーターを用いて、キシレン中に浸漬して測定した。測定に際して、脱泡を十分に行った。（ＪＩＳ Ｈ１９０２に準じて実施）
軽装密度は、充填容器として市販の１００ｍｌのメスシリンダーを使用し、ＪＩＳ Ｋ５１０１に準じて測定した。
平均粒径は、含窒素シラン化合物の透過型電子顕微鏡観察を行い、顕微鏡写真上で粒径分布を計測して、一次粒子の平均粒径を求めた。
比表面積は、島津−マイクロメリティックス製フローソーブ２３００形を使用し、ＢＥＴ一点法にり測定した。
酸素含有量は、ＬＥＣＯ社製ＴＣ−１３６型酸素・窒素同時分析装置を使用して不活性ガス融解−赤外線吸収法により測定した。
炭素含有量は、ＬＥＣＯ社製ＷＲ−１２型炭素分析装置を使用して、燃焼−熱伝導度法により測定した。
【００２６】
【表２】
〔窒化ケイ素粉末の製造〕
生成した含窒素シラン化合物を、酸素を０．５％含有する窒素雰囲気下に１０００℃で加熱分解して、非晶質窒化ケイ素粉末を得た。次いで、得られた非晶質窒化ケイ素粉末を振動ミルにて摩砕処理した後、電気炉にて、窒素雰囲気下、１００℃／ｈの昇温速度で１５５０℃まで昇温し、同温度で１時間保持して、灰白色の窒化ケイ素粉末を得た。
得られた窒化ケイ素粉末の走査型電子顕微鏡による観察では、０．０５〜０．５μｍの等軸的な粒状粒子のみが認められた。
【００２８】
使用試験例
実施例１〜１４及び比較例１〜８で得られた窒化ケイ素粉末を用いて、下記の製造方法により焼結体をそれぞれ製造した。
〔焼結体の製造〕
窒化ケイ素粉末にＹｂ２Ｏ３６重量％、Ａｌ２Ｏ３１．５重量％及びＨｆＯ２ ０．５重量％を加え、ボールミルにて湿式混合した後、２ｔｏｎ／ｃｍ２ の圧力でラバープレス成形して成形体を作製した。この成形体を、窒化ケイ素製ルツボに充填し、電気炉にて１気圧の窒素雰囲気中、昇温速度２００℃／ｈで昇温し、１７７０℃で４時間保持して窒化ケイ素質焼結体を得た。
得られた焼結体の到達密度、曲げ強度及び破壊靱性を〔表３〕に示す。尚、焼結体の嵩密度はアルキメデス法で、曲げ強度の測定はＪＩＳ Ｒ １６０１規定の四点曲げ試験で、破壊靱性値はＪＩＳ Ｒ １６０７規定のＳＥＰＢ法で測定した。
また、得られた焼結体より、所定形状のテストピースを切り出し、表面を平滑に研削、研磨した。このテストピースを箱型電気炉に入れ、空気流通下１３００℃で１００時間加熱処理した後の重量増加を測定した。試料の重量増加を、その外表面積で割った値を酸化増量（ｇ／ｍ２ ）とした。また、同一条件で酸化処理した抗析試験片の室温における四点曲げ強度を測定して、酸化後強度を判定した。
【００２９】
【表３】
【発明の効果】
本発明の含窒素シラン化合物を出発原料として用いることにより、高強度、高靱性、高信頼性、高耐酸化性の窒化ケイ素セラミックスを再現性良く安定して製造できる窒化ケイ素粉末を製造することができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a novel nitrogen-containing silane compound, specifically, among silicon nitride ceramics used as structural ceramics, particularly suitable as a starting material for producing high-strength, high-toughness silicon nitride ceramics. Nitrogen-containing silane compounds.
[0002]
[Prior art and its problems]
Silicon nitride ceramics have excellent properties such as high strength, high toughness, and high corrosion resistance, and are being used in various fields as structural materials and mechanical parts used at temperatures of 1000 ° C. or lower.
In the sintering of silicon nitride, usually, an oxide such as Y 2 O 3 or Al 2 O 3 is added in an amount of about 5 to 10% by weight, and sintering is performed. There was a disadvantage that the mechanical properties changed. In order to prevent a change in mechanical properties due to such a change in sintering conditions and to produce silicon nitride ceramics capable of stably exhibiting excellent mechanical properties regardless of sintering conditions, Y 2 O 3 , In parallel with the search for sintering aids such as MgO and Sc 2 O 3 and the study of the dispersion of hard particles such as Cr 2 N, NbB, TaSi 2 and ZrSi 2 , the production of silicon nitride powder as a raw material for producing a sintered body Research is also being conducted on conditions.
[0003]
Hitherto, as a method for producing silicon nitride powder, an imide decomposition method in which a silicon halide is reacted with ammonia is known, and silicon nitride powder produced by this method is easily sintered and has excellent sintering properties. It is said to show physical performance.
Accordingly, as a result of a detailed study of the relationship between the powder characteristics of the nitrogen-containing silane compound as a starting material of the imide decomposition method and the sinterability and characteristics of the sintered body of the obtained silicon nitride powder, it was found that nitrogen-containing compounds having specific powder characteristics In the case of using a silane compound, they have found that by sintering the obtained silicon nitride powder under normal sintering conditions, it is possible to stably produce silicon nitride ceramics having excellent mechanical properties with good reproducibility. Was.
[0004]
[Object of the invention]
An object of the present invention is to provide a nitrogen-containing silane compound as a starting material for producing a silicon nitride powder capable of producing a silicon nitride ceramic having excellent mechanical properties stably with good reproducibility.
[0005]
[Means for Solving the Problems]
In the present invention, the true density is 1.4 to 1.9 g / cm 3 , the light packaging density is 0.045 to 0.090 g / cm 3 , the specific surface area is 600 to 1000 m 2 / g, and the oxygen content is 3 The present invention relates to a nitrogen-containing silane compound mainly composed of silicon diimide having a carbon content of 0.5% by weight or less and a carbon content of less than 0.25% by weight.
The nitrogen-containing silane compound of the present invention is mainly composed of silicon diimide represented by the chemical formula Si (NH) 2 . The nitrogen content of the nitrogen-containing silane compound is 45.5 to 51.5% by weight, and the silicon content is 44.5 to 51.5% by weight.
[0006]
In silicon diimide, since silicon atoms and nitrogen atoms form a three-dimensional network structure, the true density varies depending on the regularity of Si—N bonds.
The nitrogen-containing silane compound of the present invention has a true density of 1.4 to 1.9 g / cm 3 , preferably 1.5 to 1.7 g / cm 3 . If the true density is less than 1.4 g / cm 3 , the crystallization shifts to a high temperature side when it is fired, and needle-like crystals are easily formed. When the proportion of the needle-like crystals increases, the strength characteristics of the obtained sintered body decrease, and the variation also increases, thereby deteriorating the reliability of the sintered body. Further, the oxidation resistance of the sintered body is also deteriorated, which causes an increase in the amount of oxidation increase and a decrease in the strength after oxidation. On the other hand, when the true density is higher than 1.9 g / cm 3 , when this is fired, crystallization shifts to a low temperature side, and angular stable granular particles are generated. However, excessively stabilized particles are not preferable because they have low sintering activity and it becomes difficult to densify them when producing a sintered body.
[0007]
The light packaging density is 0.045 to 0.090 g / cm 3 , and preferably 0.055 to 0.085 g / cm 3 . When the light packaging density is less than 0.045 g / cm 3 , the β-fraction of the silicon nitride powder obtained by firing the powder decreases, and the agglomeration of the powder increases. As a result, when the sintering aid is mixed with a sintering aid by a wet ball mill or the like, it is difficult to uniformly disperse the aid. The β fraction of the silicon nitride powder has an optimum value, and an excessively low β fraction is not preferable. In addition, as an effect of making uniform mixing with the auxiliary agent difficult, there is a problem that the room temperature strength and the high temperature strength of the sintered body are reduced. On the other hand, if the light packaging density is greater than 0.090 g / cm 3 , the β fraction of the silicon nitride powder obtained by calcining the powder increases, and the agglomeration of the powder is weakened to facilitate crushing. For this reason, when mixing with a sintering aid by a wet ball mill or the like, the aid can be uniformly dispersed. However, it is not preferable because the press density of the compact decreases and the fracture toughness of the sintered compact decreases.
[0008]
The specific surface area 600~1000m 2 / g, preferably from of 700-800m 2 / g. When the specific surface area is smaller than 600 m 2 / g, the agglomeration index of the powder obtained by firing this becomes large, and the high temperature strength of the finally obtained sintered body decreases. On the other hand, if it is larger than 1000 m 2 / g, the α fraction of the silicon nitride powder decreases, and the sinterability deteriorates.
The oxygen content is 3.5% by weight or less, preferably 2.5% by weight or less. When the oxygen content is more than 3.5% by weight, the obtained silicon nitride powder has good sinterability, but the high-temperature strength of the obtained sintered body decreases. Moreover, since the internal oxygen content of the obtained silicon nitride powder increases, the post-oxidation strength of the obtained sintered body decreases.
Further, when a nitrogen-containing silane compound is produced, a carbon-containing substance (for example, toluene) is mixed as an impurity from a raw material or a reaction solvent, and its content is less than 0.25% by weight in terms of carbon, preferably, , Less than 0.10% by weight. When the carbon content is 0.25% by weight or more, the carbon content of the silicon nitride powder obtained by baking the nitrogen-containing silane compound becomes larger than 0.10% by weight, and as a result, the sinterability deteriorates. It is not preferable.
[0009]
Furthermore, it is desirable that the nitrogen-containing silane compound of the present invention has an average particle diameter, a metal impurity content, and a halogen content within the following ranges in order to achieve the intended object.
The average particle size is desirably 100 nm or less. If the average particle size is larger than 100 nm, needle-like crystals are likely to be generated when this is fired. When the proportion of the needle-like crystals increases, the strength characteristics of the obtained sintered body decrease, and the variation also increases, thereby deteriorating the reliability of the sintered body. Further, the oxidation resistance of the sintered body is also deteriorated, which causes an increase in the amount of oxidation increase and a decrease in the strength after oxidation.
Metal impurities remain in the fired powder as they are, but metal impurities are a source of destruction of the sintered body. There must be. In the present invention, the content of metal impurities is desirably 100 ppm or less. If the metal impurity content is more than 100 ppm, the strength of the obtained sintered body will decrease. Furthermore, the composition change of the grain boundary of the obtained sintered body, impurity segregation at the grain boundary occurs, the oxidation resistance of the sintered body is deteriorated, the increase in the amount of oxidation is increased, and the strength after oxidation is reduced.
It is desirable that the halogen content be 180 ppm or less. About half of the halogen contained in the nitrogen-containing silane compound remains in the calcined powder. Halogen contained in the silicon nitride powder gathers in the grain boundary phase of the sintered body and has an effect of lowering the softening temperature of the grain boundary phase. For this reason, when the halogen content is more than 180 ppm, the high-temperature strength of the finally obtained sintered body decreases, and the oxidation resistance also deteriorates.
[0010]
The method for producing a nitrogen-containing silane compound of the present invention is not particularly limited as long as a nitrogen-containing silane compound having the above properties can be obtained. For example, as described below, a halogenated silane is reacted with liquid ammonia. It can be manufactured by the following. That is, in a lower organic solvent layer of a reaction system in which liquid ammonia and an organic solvent which is slightly soluble in liquid ammonia and has a specific gravity larger than liquid ammonia are separated into two layers by a difference in specific gravity, the halogenated silane and the organic solvent By supplying a mixed solution of the above, the halogenated silane is reacted with the liquid ammonia. Then, the nitrogen-containing silane compound generated by the reaction is washed with liquid ammonia to remove by-product ammonium halide.
[0011]
In the above reaction, by setting the pressure in the range of 0.54 to 13.6 atm and the reaction temperature in the range of -45 to 36 ° C, the nitrogen-containing silane having a true density in the range of 1.4 to 1.9 g / cm 3. Compounds can be synthesized. The true density can be controlled in the range of 1.5 to 1.7 g / cm 3 by setting the pressure to 1.5 to 7.2 atm and the reaction temperature to -25 to 15 ° C.
In addition, by changing the drying time and the number of rotations for stirring when drying the generated nitrogen-containing silane compound using a jacket-type stirring tank or the like, the light-weight density of the nitrogen-containing silane compound is 0.045 to 0.090 g / cm 3. Can be controlled within the range. Since the relationship between the drying condition and the light packaging density varies depending on the dryer used, the relational expression between the two may be examined in advance to set the conditions appropriately.
[0012]
Further, by changing the ratio (by volume) of the halogenated silane and liquid ammonia in the reaction in the range of 0.030 to 0.047, preferably 0.035 to 0.041, the specific surface area of 600 to A nitrogen-containing silane compound of 1000 m 2 / g, preferably 700 to 800 m 2 / g can be synthesized.
In the initial stage of the reaction, liquid ammonia is present in a large excess, but since ammonia is consumed as the reaction proceeds, liquid ammonia is also continuously supplied to the reaction tank. Then, in a steady state, the volume ratio of the halogenated silane and the liquid ammonia supplied into the reaction vessel is changed.
The oxygen content of the nitrogen-containing silane compound is not more than 3.5% by weight, preferably by reducing the water content in the liquid ammonia used for washing the nitrogen-containing silane compound obtained by the above reaction as much as possible. , 2.5% by weight or less.
Specifically, the product (H × W) of the water content H (ppm) in the liquid ammonia and the cleaning liquid amount / nitrogen-containing silane compound amount W (l / kg) is 31500 or less, preferably 22500 or less. .
Similarly, by setting the content of the organic compound in the liquid ammonia used for washing the nitrogen-containing silane compound to 1500 ppm or less, preferably 600 ppm or less, the carbon content of the nitrogen-containing silane compound is 0.25% by weight. %, Preferably less than 0.10% by weight.
[0013]
The average particle size of the nitrogen-containing silane compound can be changed by controlling both the temperature of the reaction vessel and the mixing ratio (volume ratio) of the halogenated silane supplied to the reaction vessel and the organic solvent for dilution. . To make the average particle size of the nitrogen-containing silane compound 100 nm or less, the mixing ratio may be 0.08 or more.
Metal impurities are mixed in due to sliding wear and contact wear of stirring blades installed inside a reaction tank, a washing tank, a dryer, and the like, and can be reduced by adjusting equipment and improving control accuracy. Specifically, the distance between the stirring blade and various metal parts (filter plate, vessel wall, etc.) is at least 5 mm, preferably at least 10 mm, and the maximum peripheral speed at the tip of the rotating blade is 5 m / s or less. By controlling, the amount of metal impurities can be reduced to 100 ppm or less.
The halogen content varies depending on the amount of liquid ammonia used when washing and removing ammonium halide from a mixture of the nitrogen-containing silane compound and ammonium halide obtained by the reaction. Usually, the halogen content can be reduced to 180 ppm or less by using liquid ammonia of 40 l or more per kg of the nitrogen-containing silane compound. The halogen content can be reduced as much as possible by using a large amount of liquid ammonia, but excessive cleaning is not economical because it leads to an increase in cost.
[0014]
Examples of the halogenated silane used in the reaction include fluorinated silanes such as SiF 4 , H 2 SiF 6 , HSiF 3 , H 3 SiF 5 , H 3 SiF, and H 5 SiF 3 , SiCl 4 , HSiCl 3 , and H 2 SiCl. 2 , chlorosilanes such as H 3 SiCl, bromosilanes such as SiBr 4 , HSiBr 3 , H 2 SiBr 2 , H 3 SiBr, and iodide silanes such as SiI 4 , HSiI 3 , H 2 SiI 2 , and H 3 SiI are used. can do. Further, RSiX 3, R 2 SiX 2 , R 3 SiX (R is CH 3, C 2 H 5, C 3 H 7 alkyl groups such as, X is a halogen) can also be used halogenated alkylsilane such.
[0015]
In addition, as the organic solvent, one that is inert to liquid ammonia or halogenated silane, does not dissolve in liquid ammonia at the reaction temperature, and has a specific gravity larger than that of liquid ammonia is used. For example, an aliphatic hydrocarbon having 5 to 7 hydrocarbons such as n-heptane, n-hexane, n-pentane and C-hexane, and a single or a mixture of aromatic hydrocarbons such as benzene, toluene and xylene are exemplified. .
[0016]
By using the nitrogen-containing silane compound of the present invention as a starting material, a silicon nitride powder capable of stably producing silicon nitride ceramics having excellent mechanical properties with good reproducibility can be produced.
First, a nitrogen-containing silane compound is calcined at a temperature in the range of 600 to 1200 ° C. in an atmosphere of an inert gas containing nitrogen or ammonia having an oxygen content of 5% or less to produce an amorphous silicon nitride powder.
At this time, the nitrogen-containing silane compound gradually decomposes from room temperature, and decomposes violently at 250 to 600 ° C. to generate ammonia.
Examples of the inert gas containing nitrogen or ammonia include nitrogen or ammonia, or a mixed gas with argon, helium, or the like.
[0017]
Next, the obtained amorphous silicon nitride powder is fired in an atmosphere of an inert gas containing nitrogen or ammonia to produce a crystalline silicon nitride powder.
The firing temperature ranges from 1400 to 1600 ° C. If the firing temperature is lower than 1400 ° C., crystallization of silicon nitride does not proceed sufficiently. On the other hand, if the firing temperature exceeds 1600 ° C., it is not preferable because a crystalline silicon nitride powder composed of coarse crystals is easily formed. Further, a rapid temperature rise is not preferable in order to make the particle shape uniform, and it is desirable to slowly raise the temperature in the range of 1150 to 1400 ° C over 1.5 hours or more.
[0018]
Examples of the heating furnace used for heating the nitrogen-containing silane compound and the amorphous silicon nitride powder include a batch-type electric furnace using a high-frequency induction heating method or a resistance heating method, a pusher furnace, a rotary kiln furnace, a shaft kiln furnace, and a fluidized firing furnace. Are used. In particular, a continuous firing furnace is an effective means for efficiently dissipating heat generated by the crystallization reaction of amorphous silicon nitride.
[0019]
The obtained silicon nitride powder is mixed with a sintering aid such as aluminum oxide, yttrium oxide, and magnesium oxide in the same manner as in the case of the conventional silicon nitride powder, and after molding the mixture into a predetermined shape, By sintering, a silicon nitride ceramic (sintered body) can be manufactured. The molding pressure may be about 0.5 to 5 ton / cm 2, and the sintering conditions are a sintering temperature of 1500 to 2000 ° C., an atmospheric pressure of 0.5 to 100 atm, and a sintering time of 1 to 10 hours. It should just be about.
[0020]
Silicon nitride ceramics (sintered body) manufactured using this silicon nitride powder have not only high strength, high toughness and high Weibull coefficient but also excellent oxidation resistance as compared with conventional ones. Therefore, it is particularly suitable as a raw material for producing silicon nitride ceramics used as a structural material for heat engines such as turbo rotors, valves, and diesel engine sub-combustion chambers used at a temperature of 1400 ° C. or lower, and mechanical parts. .
[0021]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples of the present invention and Comparative Examples.
Examples 1 to 14 and Comparative Examples 1 to 8
(Production of nitrogen-containing silane compound)
At the temperature and pressure shown in Table 1, the air in the vertical reaction tank having a diameter of 30 cm and a height of 45 cm was replaced with nitrogen gas, and then liquid ammonia and toluene were charged. In the reaction tank, it was separated into liquid ammonia in the upper layer and toluene in the lower layer. A solution consisting of silicon tetrachloride and toluene prepared in the proportions shown in Table 1 was supplied to the slowly stirred lower layer through a conduit. With the supply of the toluene solution, a white reaction product was deposited near the interface between the upper and lower layers.
After the completion of the reaction, the reaction solution was transferred to a filtration tank, and the product was separated by filtration and washed with liquid ammonia to obtain a nitrogen-containing silane compound mainly composed of silicon diimide.
[0022]
In the above reaction, the true density was controlled by changing the reaction temperature.
In addition, the light packing density was controlled by changing the drying time and the stirring rotation speed when drying the produced nitrogen-containing silane compound with heated steam using a jacket-type stirring tank (with two blade paddles inclined at 45 degrees). As for the drying time, since the temperature starts to rise when the solvent is completely removed, the time point at which the temperature of the powder layer starts to rise was defined as the end point of the drying.
The specific surface area was controlled by changing the ratio (by volume) of silicon tetrachloride and liquid ammonia during the reaction. In the initial stage of the reaction, liquid ammonia is present in a large excess, but since ammonia is consumed as the reaction proceeds, liquid ammonia is also continuously supplied to the reaction tank. The nitrogen-containing silane compounds having various specific surface areas were synthesized by changing the volume ratio of silicon tetrachloride and liquid ammonia supplied into the reaction vessel in the steady state within the range shown in [Table 1].
[0023]
The oxygen content was controlled by changing the amount of water in the liquid ammonia used for washing the produced nitrogen-containing silane compound in the range shown in [Table 1].
Similarly, the carbon content was controlled by changing the toluene content in the liquid ammonia used for washing the nitrogen-containing silane compound in the range shown in [Table 1].
The average particle size was controlled by changing the temperature of the reaction tank and the volume ratio of silicon tetrachloride and toluene supplied to the reaction tank within the range shown in [Table 1].
The chlorine content was controlled by changing the amount of liquid ammonia used in washing the nitrogen-containing silane compound in the range shown in [Table 1].
Metal impurities changed depending on the adjustment state of the stirring blade.
[0024]
[Table 1]
The powder properties of the obtained nitrogen-containing silane compound are shown in [Table 2].
The true density of the nitrogen-containing silane compound was measured by using dehydrated xylene as a medium and immersing it in xylene using a pycnometer. During the measurement, defoaming was sufficiently performed. (Conducted according to JIS H1902)
The light packaging density was measured according to JIS K5101, using a commercially available 100 ml measuring cylinder as a filling container.
The average particle diameter was obtained by observing the nitrogen-containing silane compound with a transmission electron microscope, measuring the particle diameter distribution on a micrograph, and calculating the average particle diameter of the primary particles.
The specific surface area was measured by a BET one point method using Flowsorb 2300 manufactured by Shimadzu-Micromeritics.
The oxygen content was measured by an inert gas melting-infrared absorption method using a TC-136 oxygen / nitrogen simultaneous analyzer manufactured by LECO.
The carbon content was measured by a combustion-thermal conductivity method using a WR-12 type carbon analyzer manufactured by LECO.
[0026]
[Table 2]
(Production of silicon nitride powder)
The generated nitrogen-containing silane compound was thermally decomposed at 1000 ° C. in a nitrogen atmosphere containing 0.5% of oxygen to obtain an amorphous silicon nitride powder. Next, the obtained amorphous silicon nitride powder was ground by a vibration mill, and then heated to 1550 ° C. in an electric furnace at a rate of 100 ° C./h under a nitrogen atmosphere. After holding for 1 hour, an off-white silicon nitride powder was obtained.
In observation of the obtained silicon nitride powder with a scanning electron microscope, only equiaxed granular particles of 0.05 to 0.5 μm were recognized.
[0028]
Use Test Examples Using the silicon nitride powders obtained in Examples 1 to 14 and Comparative Examples 1 to 8, sintered bodies were manufactured by the following manufacturing methods.
[Manufacture of sintered body]
6% by weight of Yb 2 O 3, 1.5% by weight of Al 2 O 3 and 0.5% by weight of HfO 2 are added to silicon nitride powder, wet-mixed by a ball mill, and then rubber-pressed at a pressure of 2 ton / cm 2. Thus, a molded body was produced. The molded body was filled in a silicon nitride crucible, heated in an electric furnace at a rate of 200 ° C./h in a nitrogen atmosphere at 1 atm, and maintained at 1770 ° C. for 4 hours to obtain a silicon nitride sintered body. Got.
The ultimate density, bending strength and fracture toughness of the obtained sintered body are shown in [Table 3]. The bulk density of the sintered body was measured by the Archimedes method, the bending strength was measured by a four-point bending test specified in JIS R 1601, and the fracture toughness was measured by the SEPB method specified in JIS R 1607.
Further, a test piece having a predetermined shape was cut out from the obtained sintered body, and the surface was smoothly ground and polished. This test piece was placed in a box-type electric furnace, and the weight increase after heating at 1300 ° C. for 100 hours under an air flow was measured. The value obtained by dividing the weight increase of the sample by its outer surface area was defined as the oxidation weight increase (g / m 2 ). In addition, the post-oxidation strength was determined by measuring the four-point bending strength at room temperature of the coagulation test specimen oxidized under the same conditions.
[0029]
[Table 3]
【The invention's effect】
By using the nitrogen-containing silane compound of the present invention as a starting material, it is possible to produce a silicon nitride powder capable of stably producing silicon nitride ceramics having high strength, high toughness, high reliability, and high oxidation resistance with good reproducibility. it can.
Claims (4)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32932496A JP3550919B2 (en) | 1995-12-12 | 1996-12-10 | Nitrogen-containing silane compounds |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7-323178 | 1995-12-12 | ||
| JP32317895 | 1995-12-12 | ||
| JP32932496A JP3550919B2 (en) | 1995-12-12 | 1996-12-10 | Nitrogen-containing silane compounds |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09221308A JPH09221308A (en) | 1997-08-26 |
| JP3550919B2 true JP3550919B2 (en) | 2004-08-04 |
Family
ID=26571088
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP32932496A Expired - Lifetime JP3550919B2 (en) | 1995-12-12 | 1996-12-10 | Nitrogen-containing silane compounds |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3550919B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010114141A1 (en) | 2009-03-30 | 2010-10-07 | 宇部興産株式会社 | Nitrogen-containing silane compound powder and method for producing same |
| CN102782085A (en) * | 2010-03-31 | 2012-11-14 | 宇部兴产株式会社 | Method for producing sialon-based acid nitride phosphor, and sialon-based acid nitride phosphor |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5589294B2 (en) * | 2009-03-30 | 2014-09-17 | 宇部興産株式会社 | Nitrogen-containing silane compound powder and method for producing the same |
| JP5589295B2 (en) * | 2009-03-30 | 2014-09-17 | 宇部興産株式会社 | Nitrogen-containing silane compound powder and method for producing the same |
-
1996
- 1996-12-10 JP JP32932496A patent/JP3550919B2/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010114141A1 (en) | 2009-03-30 | 2010-10-07 | 宇部興産株式会社 | Nitrogen-containing silane compound powder and method for producing same |
| CN102782085A (en) * | 2010-03-31 | 2012-11-14 | 宇部兴产株式会社 | Method for producing sialon-based acid nitride phosphor, and sialon-based acid nitride phosphor |
| CN104087291A (en) * | 2010-03-31 | 2014-10-08 | 宇部兴产株式会社 | Production method of sialon-based oxynitride phosphor, and sialon-based oxynitride phosphor |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH09221308A (en) | 1997-08-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1083789A (en) | Silicon carbide sintered moldings and a method for producing the same | |
| US4571331A (en) | Ultrafine powder of silicon carbide, a method for the preparation thereof and a sintered body therefrom | |
| Riedel et al. | Polymer-derived Si-based bulk ceramics, part I: Preparation, processing and properties | |
| JP5862765B2 (en) | Method for producing silicon nitride powder, silicon nitride powder, and method for producing silicon nitride sintered body | |
| JPS6048474B2 (en) | Silicon nitride sintered body and its manufacturing method | |
| Kansal et al. | A processable mullite precursor prepared by reacting silica and aluminum hydroxide with triethanolamine in ethylene glycol: structural evolution on pyrolysis | |
| JP3550919B2 (en) | Nitrogen-containing silane compounds | |
| JP3475614B2 (en) | Silicon diimide | |
| EP0143122A2 (en) | An ultrafine powder of silcon carbide, a method for the preparation thereof and a sintered body therefrom | |
| Seyferth et al. | Preparation of boron-containing ceramic materials by pyrolysis of the decaborane (14)-derived [B10H12. cntdot. Ph2POPPh2] x polymer | |
| US4122140A (en) | Hot pressing of silicon nitride using beryllium additive | |
| Hasegawa | Porous reduced ceramic monoliths derived from silicon-and titanium-based preceramic polymer gels | |
| CN112777598B (en) | Method for preparing high-purity beta-silicon carbide micro-nano powder by high-temperature carbon-embedded carbothermic reduction | |
| Ziegenbalg et al. | Synthesis of α-silicon nitride powder by gas-phase ammonolysis of CH3SiCl3 | |
| CN1036262C (en) | Process for the preparation of powder for ceramics made of metal and/or metalloid nitride and/or carbide by flash... | |
| Schwab et al. | The influence of preceramic binders on the microstructural development of silicon nitride | |
| Boden et al. | Nanosized Si C N-powders by polysilazane pyrolysis and Si3N4SiC-composite materials thereof | |
| Ramesh et al. | Preparation and characterization of single‐phase β‐sialon | |
| JP3536494B2 (en) | Nitrogen-containing silane compounds | |
| Iwamoto et al. | Si3N4–TiN–Y2O3 ceramics derived from chemically modified perhydropolysilazane | |
| JP2855602B2 (en) | Method for producing silicon nitride powder | |
| JPS638265A (en) | Manufacture of composite sintered body | |
| Liu et al. | Fabrication of practically pure Si2N2O ceramic with high performance from amorphous BN surface modified nano-sized Si3N4 powders | |
| JPH10316469A (en) | Powdery magnesium silicide nitride and its production | |
| JPH0532451A (en) | Production of sintered ceramic |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20040330 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20040412 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090514 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090514 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100514 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110514 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120514 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120514 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120514 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130514 Year of fee payment: 9 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130514 Year of fee payment: 9 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130514 Year of fee payment: 9 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140514 Year of fee payment: 10 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| EXPY | Cancellation because of completion of term |