JP2970400B2 - Method for producing high α-type silicon nitride powder - Google Patents
Method for producing high α-type silicon nitride powderInfo
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- JP2970400B2 JP2970400B2 JP6120674A JP12067494A JP2970400B2 JP 2970400 B2 JP2970400 B2 JP 2970400B2 JP 6120674 A JP6120674 A JP 6120674A JP 12067494 A JP12067494 A JP 12067494A JP 2970400 B2 JP2970400 B2 JP 2970400B2
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- copper
- silicon nitride
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- silicon
- nitride powder
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Description
【0001】[0001]
【産業上の利用分野】本発明は、高α型窒化ケイ素粉末
の製造方法に関するものである。The present invention relates to a method for producing a high α-type silicon nitride powder.
【0002】[0002]
【従来の技術及び発明が解決しようとする課題】窒化ケ
イ素焼結体は、高温における材料強度、耐熱衝撃性、耐
食性に優れているために耐熱構造材料としての需要の増
加が期待されている。特に、α型結晶相比率(以下、
“α化率”と記す)が90%(重量%、以下同じ)以上
の窒化ケイ素粉末は、高α型窒化ケイ素粉末と呼ばれ、
この粉末を焼結した焼結体は高温における材料強度が極
めて高いことが知られている。従来、窒化ケイ素の工業
的製造方法としては、(1)直接窒化法、(2)還元窒
化法、(3)ハロゲン化イミド法が良く知られている。
これらのうち、直接窒化法が、価格的にも優れ、最も一
般的な方法として広くその製品が使用されている。2. Description of the Related Art Silicon nitride sintered bodies are expected to increase in demand as heat-resistant structural materials due to their excellent material strength, thermal shock resistance and corrosion resistance at high temperatures. In particular, the α-type crystal phase ratio (hereinafter, referred to as
Silicon nitride powder having 90% (weight%, hereinafter the same) or more of which is referred to as “high α-type silicon nitride powder”
It is known that a sintered body obtained by sintering this powder has extremely high material strength at high temperatures. Conventionally, (1) direct nitriding method, (2) reduction nitriding method, and (3) halogenated imide method are well known as industrial methods for producing silicon nitride.
Among these, the direct nitriding method is excellent in cost, and its product is widely used as the most common method.
【0003】この方法は、下記の化学式に示すように、
1mol当り176kcalという多量の発熱を伴う反
応であることが知られている。 3Si+2N2→Si3N 4+176kcal[0003] In this method, as shown in the following chemical formula,
Anti-gas with a large amount of heat generation of 176 kcal / mol
It is known to be responsive. 3Si + 2NTwo→ SiThreeN Four+ 176kcal
【0004】そのため急激な反応を抑え、極力均一な反
応温度分布を得るために、反応装置としてトンネル炉を
利用するような場合には、トレイへの仕込量を調節した
り、昇温速度を制御することやより均一な反応温度を得
るために特開昭61−97110号,61−26630
5号公報、特開平3−60410号公報等に示されてい
るように回転炉や流動層を反応装置として用いることが
提案されている。[0004] Therefore, when a tunnel furnace is used as a reactor in order to suppress a rapid reaction and obtain a uniform reaction temperature distribution as much as possible, the amount charged to a tray is adjusted or the rate of temperature rise is controlled. And Japanese Patent Application Laid-Open No. 61-97110, 61-26630 to obtain a more uniform reaction temperature.
No. 5, JP-A-3-60410, etc., it has been proposed to use a rotary furnace or a fluidized bed as a reactor.
【0005】一方、この反応は、窒素ガスと固体状金属
ケイ素のいわゆる気−固系反応であり、見かけ上窒素ガ
スの金属ケイ素内への拡散や生成した窒化ケイ素内への
拡散が反応を律速していると言われている。そこで、通
常であれば拡散速度を早めるために、反応温度を高くす
る方法や反応圧力を高める方法が考えられる。しかしな
がら、窒化ケイ素の生成反応においては、高温になるほ
どβ型窒化ケイ素が生成し、目的とするα型窒化ケイ素
が得られないという問題があり、また圧力の効果は、余
程の高圧でないかぎりその効果はほとんど期待できない
ことが報告されている(表面;24(No.7),36
3,’86)。また、工業的スケールでの実施を勘案す
ると超高圧を維持するための装置を反応装置として使用
することは経済性がなく、工業規模での実施も困難とな
る。On the other hand, this reaction is a so-called gas-solid reaction between nitrogen gas and solid metallic silicon, and apparently diffusion of nitrogen gas into metallic silicon and diffusion into generated silicon nitride limit the reaction. Is said to be. Therefore, in order to increase the diffusion rate, a method of increasing the reaction temperature or a method of increasing the reaction pressure is usually considered. However, in the production reaction of silicon nitride, there is a problem that β-type silicon nitride is generated as the temperature increases, and the desired α-type silicon nitride cannot be obtained. It has been reported that almost no effect can be expected (surface; 24 (No. 7), 36).
3, '86). Also, considering the implementation on an industrial scale, it is not economical to use a device for maintaining an ultra-high pressure as a reactor, and implementation on an industrial scale becomes difficult.
【0006】そのためこの問題を解決する方法の一つと
して反応ガスに水素ガスを混合して使用する方法がある
ことは良く知られている。Therefore, it is well known that one method of solving this problem is to use a mixture of hydrogen gas and a reaction gas.
【0007】また、触媒を添加することにより比較的容
易に高α型窒化ケイ素粉末を製造する方法も提案されて
いる。例えば、特開昭50−128698号公報では
K,Na,Liの化合物、特開昭51−48800号公
報では酸化マグネシウム、特開昭54−15499号公
報では金属鉄及び鉄化合物、特開昭54−22000号
公報ではアルカリ土類金属のハロゲン化物、特開昭54
−57499号公報では窒化アルミニウム、特開昭54
−58700号公報では酸化パラジウム、特開昭54−
120298号公報ではカルシウム化合物、特開昭59
−92906号公報では銅化合物、特開昭61−256
906号公報ではバナジウム化合物が各々高α型窒化ケ
イ素の製造に効果のあることが開示されている。Further, there has been proposed a method for relatively easily producing a high α-type silicon nitride powder by adding a catalyst. For example, K, Na, and Li compounds are disclosed in JP-A-50-128698, magnesium oxide in JP-A-51-48800, metallic iron and iron compounds in JP-A-54-15499, and JP-A-54-15499. No. 22000 discloses halides of alkaline earth metals.
No. 57499 discloses aluminum nitride.
No. 58700 discloses palladium oxide,
Japanese Patent No. 120298 discloses a calcium compound,
Japanese Patent Application Laid-Open No. 61-256 discloses a copper compound.
No. 906 discloses that each vanadium compound is effective in producing high α-type silicon nitride.
【0008】本発明者等は、これら公知の方法を参考に
鋭意検討した結果、銅又は銅化合物を触媒として使用す
ることにより、他の触媒に比べ遥かに効率的に高α型窒
化ケイ素粉末を製造できることを見い出したが、上記の
特開昭59−92906号公報において提案されている
方法では、銅又は銅化合物の添加量が金属ケイ素に対し
て0.5%〜10%と多量であるため、製品の精製工程
での銅又は銅化合物の除去に問題があった。つまり、通
常当業界で行われる精製は、酸処理が一般的であるが、
多量に銅又は銅化合物を添加する方法では経済的に銅又
は銅化合物を完全に除去することは困難であり、その結
果得られた窒化ケイ素粉末を原料として成形・焼結して
得られる製品では、所定の強度が得られないという問題
点を有していた。また金属ケイ素に対して最大10%の
銅を触媒として添加することは窒化ケイ素の経済的製造
法という観点からも好ましいことではない。The present inventors have conducted intensive studies with reference to these known methods. As a result, the use of copper or a copper compound as a catalyst makes it possible to produce a high α-type silicon nitride powder much more efficiently than other catalysts. It has been found that it can be produced, but in the method proposed in JP-A-59-92906, the amount of copper or copper compound added is as large as 0.5% to 10% with respect to metal silicon. In addition, there is a problem in removing copper or a copper compound in a product refining process. In other words, the purification usually performed in the art is generally performed by acid treatment,
It is difficult to completely remove copper or a copper compound economically by a method of adding a large amount of copper or a copper compound, and in a product obtained by molding and sintering the resulting silicon nitride powder as a raw material, However, there is a problem that a predetermined strength cannot be obtained. In addition, it is not preferable to add a maximum of 10% of copper to metal silicon as a catalyst from the viewpoint of an economical production method of silicon nitride.
【0009】本発明は、上記事情に鑑みなされたもの
で、窒化ケイ素焼結体の強度を低下させることのない程
度にまで通常の方法で銅又は銅化合物の除去ができる効
率的かつ工業的スケールで経済的な高α型窒化ケイ素粉
末の製造方法を提供することを目的とする。The present invention has been made in view of the above circumstances, and is an efficient and industrial scale capable of removing copper or a copper compound by a usual method to such an extent that the strength of a silicon nitride sintered body is not reduced. It is an object of the present invention to provide an economical and economical method for producing high α-type silicon nitride powder.
【0010】[0010]
【課題を解決するための手段及び作用】本発明者等は、
上記問題点を解決するため鋭意検討を行った結果、特開
昭59−92906号公報で開示されているように銅又
は銅化合物が高α型窒化ケイ素粉末の効率的製造に欠く
ことのできない触媒作用を有していることを確認すると
同時に、当該公報に示されている量より少量の添加量
で、金属ケイ素粉末に銅又は銅化合物を添加し、混合機
で十分に混合した混合物を原料にし、窒素又はアンモニ
アを含む非酸化性雰囲気下、1,000〜1,500℃
で窒化反応させることにより、高α型窒化ケイ素粉末が
効率的に製造でき、銅触媒の効果を十分に発揮させ得る
ことを見い出した。Means and Action for Solving the Problems The present inventors have
As a result of intensive studies to solve the above problems, as disclosed in JP-A-59-92906, a catalyst in which copper or a copper compound is indispensable for efficient production of high α-type silicon nitride powder. At the same time as confirming that it has the effect, copper or copper compound is added to the silicon metal powder with an addition amount smaller than the amount indicated in the gazette, and a mixture sufficiently mixed with a mixer is used as a raw material. 1,000 to 1,500 ° C under a non-oxidizing atmosphere containing nitrogen or ammonia
It has been found that a high α-type silicon nitride powder can be efficiently produced by performing a nitridation reaction at, and the effect of the copper catalyst can be sufficiently exerted.
【0011】すなわち、本発明者等は、高α型窒化ケイ
素粉末を製造するための触媒について種々検討を行った
結果、銅を触媒として用いることで容易にα化率の高い
窒化ケイ素が得られるとの知見を得ることができた。こ
の場合、検討に用いた触媒の内で、銅は、鉄やカルシウ
ム等の他の触媒作用の認められる物質に比較して金属ケ
イ素内での拡散係数が格段に大きいことが前述の他の触
媒効果を有する物質に比較して反応促進により寄与して
いる可能性が高いと考えられる〔E.M.Pell:P
hys.Rev.,119,1014 and 122
2(1960)〕。更に、銅の熱伝導率が他の触媒に比
較して大きいことも反応熱のコントロールに好影響を与
え、高温安定型のβ型窒化ケイ素の生成を抑制している
可能性もある。That is, the present inventors have conducted various studies on a catalyst for producing a high α-type silicon nitride powder. As a result, silicon nitride having a high α-formation ratio can be easily obtained by using copper as a catalyst. Was obtained. In this case, among the catalysts used in the study, copper has a significantly higher diffusion coefficient in metallic silicon compared to other catalytically active substances such as iron and calcium. It is considered that it is more likely to contribute to the reaction promotion than a substance having an effect [E. M. Pell: P
hys. Rev .. , 119, 1014 and 122.
2 (1960)]. Furthermore, the fact that copper has a higher thermal conductivity than other catalysts also has a favorable effect on the control of the heat of reaction, and may possibly suppress the production of high-temperature stable β-type silicon nitride.
【0012】ところが、一方で銅の密度は8.93g/
cm3(20℃)であり、金属ケイ素の密度2.35g
/cm3(15℃無定形)に比較して大きいので、この
両者を均一に混合するためには困難が伴う。従って、十
分な触媒効果を容易に得るために、従来技術にあるよう
に過剰に添加するという方法が一般的には採用される。
しかし、ここで過剰に添加された銅は、必ずしも均一に
分散せず、窒化生成物中に偏析することになる。直接窒
化法による窒化ケイ素の製造工程では一般的に製品の純
度を確保するために酸による不純物除去工程があり、当
該工程で大方の不純物は許容レベルにまで除去される
が、過剰に添加された銅又は銅化合物は、通常の方法で
は許容レベルにまで除去できず、その結果、当該窒化ケ
イ素粉末を使用した焼結体の強度に悪影響を及ぼしてい
たものである。However, on the other hand, the density of copper is 8.93 g /
cm 3 (20 ° C.) and the density of metallic silicon is 2.35 g
/ Cm 3 (amorphous at 15 ° C.), it is difficult to uniformly mix the two. Therefore, in order to easily obtain a sufficient catalytic effect, a method of excessive addition as in the prior art is generally adopted.
However, the excessively added copper does not necessarily disperse uniformly, but segregates in the nitrided product. In the production process of silicon nitride by the direct nitridation method, there is generally an impurity removal process using an acid to secure the purity of the product, and most of the impurities are removed to an allowable level in the process, but excessively added. Copper or copper compounds cannot be removed to an acceptable level by ordinary methods, and as a result, have adversely affected the strength of the sintered body using the silicon nitride powder.
【0013】しかしながら、本発明者等の検討によれ
ば、銅又は銅化合物を金属ケイ素粉末に対し銅換算で
0.5%未満、より好ましくは0.4%以下の少量を添
加し、混合度が0.9以上になるように均一分散させれ
ば、銅触媒を0.5%以上の多量に添加する場合と同等
の高α化率が達成されると共に、得られた窒化ケイ素は
単に通常の酸処理をするだけで高純度化され、強度の大
きい焼結体を与える高α型窒化ケイ素粉末を効率よく低
コストで、しかも簡単かつ確実に製造し得ることを知見
した。However, according to the study of the present inventors, a small amount of copper or copper compound is added to the metal silicon powder in a small amount of less than 0.5%, more preferably 0.4% or less in terms of copper. Is uniformly dispersed so as to be not less than 0.9, a high α-conversion rate equivalent to the case where a copper catalyst is added in a large amount of 0.5% or more is achieved, and the obtained silicon nitride is simply produced by a conventional method. It has been found that a high α-type silicon nitride powder which is highly purified only by treating with acid and gives a sintered body with high strength can be produced efficiently, at low cost, easily and reliably.
【0014】またこの場合、銅触媒を少量添加するとい
う効果をより確実に発揮させるために、また特に流動層
や回転炉等の分級を起こし易い反応器を用いる際に、金
属ケイ素粉末に銅又は銅化合物を添加、混合した混合粉
末をポリビニルアルコール、メチルセルロース、セルロ
ース誘導体、でんぷん等の結合剤を用いて、成形又は造
粒したもの、或いは更にアルゴン、ヘリウム等の不活性
ガス雰囲気下(常圧、減圧)や真空下などの不活性雰囲
気下に焼結した成形体あるいは粉末を用いたり、上記混
合粉末を溶融させてケイ素−銅合金を得、これを所定粒
度に粉砕した粉砕物を用いることが有効であることを見
い出し、本発明をなすに至ったものである。In this case, in order to more reliably exert the effect of adding a small amount of a copper catalyst, and particularly when using a reactor such as a fluidized bed or a rotary furnace which is likely to cause classification, copper or metal is added to the metal silicon powder. The copper powder was added and mixed, and the mixed powder was molded or granulated using a binder such as polyvinyl alcohol, methylcellulose, cellulose derivative or starch, or further under an inert gas atmosphere such as argon or helium (normal pressure, It is possible to use a compact or powder sintered under an inert atmosphere such as under reduced pressure or vacuum, or to use a pulverized product obtained by melting the above mixed powder to obtain a silicon-copper alloy and pulverizing it to a predetermined particle size. The inventors have found that the present invention is effective, and have accomplished the present invention.
【0015】従って、本発明は、 (1)金属ケイ素粉末に銅又は銅化合物の少なくとも一
種を金属ケイ素に対して銅換算で0.05重量%以上
0.5重量%未満添加し、混合度が0.9以上になるよ
うに混合し、該混合物を窒素又はアンモニアを含む非酸
化性ガス雰囲気中で1,000〜1,500℃の温度範
囲にて窒化することを特徴とする高α型窒化ケイ素粉末
の製造方法、 (2)金属ケイ素粉末に銅又は銅化合物の少なくとも一
種を金属ケイ素に対して銅換算で0.05重量%以上
0.5重量%未満添加し、混合度が0.9以上となるよ
うに混合し、該混合物を結合剤を用いて成形した成形物
又はこの成形物を不活性雰囲気中常圧もしくは減圧で又
は真空中で焼結した焼結物を窒素又はアンモニアを含む
非酸化性ガス雰囲気中で1,000〜1,500℃の温
度範囲にて窒化することを特徴とする高α型窒化ケイ素
粉末の製造方法、及び、 (3)金属ケイ素粉末に銅又は銅化合物の少なくとも一
種を金属ケイ素に対して銅換算で0.05重量%以上
0.5重量%未満配合・溶融させてケイ素−銅合金を作
った後、再度所定の粒度に粉砕した粉砕物を窒素又はア
ンモニアを含む非酸化性ガス雰囲気中で1,000〜
1,500℃の温度範囲にて窒化することを特徴とする
高α型窒化ケイ素粉末の製造方法を提供する。Therefore, the present invention provides: (1) at least one of copper or a copper compound is added to metallic silicon powder in an amount of 0.05% by weight or more and less than 0.5% by weight in terms of copper with respect to metallic silicon; High α-type nitriding, wherein the mixture is mixed at a temperature of 1,000 to 1,500 ° C. in a non-oxidizing gas atmosphere containing nitrogen or ammonia. (2) At least one of copper or a copper compound is added to metal silicon powder in an amount of 0.05% by weight or more and less than 0.5% by weight in terms of copper with respect to metal silicon, and the degree of mixing is 0.9. The mixture is mixed as described above, and the mixture is molded using a binder, or a molded product obtained by sintering the molded product in an inert atmosphere at normal pressure or reduced pressure or in a vacuum is a non-containing product containing nitrogen or ammonia. 1,0 in an oxidizing gas atmosphere A method for producing a high α-type silicon nitride powder characterized by nitriding in a temperature range of 00 to 1,500 ° C., and (3) at least one of copper or a copper compound to metal silicon A silicon-copper alloy is prepared by blending and melting 0.05% by weight or more and less than 0.5% by weight in terms of copper, and then pulverized to a predetermined particle size again in a non-oxidizing gas atmosphere containing nitrogen or ammonia. 1,000 ~
Provided is a method for producing a high α-type silicon nitride powder characterized by nitriding in a temperature range of 1,500 ° C.
【0016】以下、本発明につき更に詳しく説明する。
本発明の高α型窒化ケイ素粉末の製造方法は、直接窒化
法によるもので、金属ケイ素粉末を窒素又はアンモニア
を含む非酸化性ガス雰囲気中で1,000〜1,500
℃にて窒化させる際に、銅又は銅化合物を0.5%未満
の少量添加して行うものである。Hereinafter, the present invention will be described in more detail.
The method for producing a high α-type silicon nitride powder of the present invention is based on a direct nitridation method, in which a metal silicon powder is prepared in a non-oxidizing gas atmosphere containing nitrogen or ammonia for 1,000 to 1,500.
When nitriding at ° C., copper or a copper compound is added in a small amount of less than 0.5%.
【0017】この場合、原料の金属ケイ素粉末として
は、粒度数μ〜149μ、特に数μ〜44μのものを使
用することが好ましい。金属ケイ素粉末の粒度が149
μを越えると窒化反応が遅くなりすぎ、窒化生成物中に
未反応の金属ケイ素が残存する場合が生じる。また、そ
の純度としては、工業スケールで得られる金属ケイ素で
十分であるが、必要に応じて半導体グレードの金属ケイ
素からAl合金用に供される金属ケイ素まで使いわける
ことができる。In this case, it is preferable to use a metal silicon powder having a particle size of several μm to 149 μm, particularly, several μm to 44 μm. Particle size of metallic silicon powder is 149
If it exceeds μ, the nitridation reaction becomes too slow, and unreacted metallic silicon may remain in the nitrided product. In addition, as the purity, metal silicon obtained on an industrial scale is sufficient, but if necessary, it can be selectively used from semiconductor-grade metal silicon to metal silicon used for Al alloys.
【0018】本発明においては、上記金属ケイ素粉末に
銅又は銅化合物を混合したものを使用して直接窒化反応
を行わせるが、金属ケイ素粉末に触媒として添加する銅
又は銅化合物の粒度は、均一性の観点からは使用する金
属ケイ素粒子と同程度の重量をもった粒子の大きさであ
ることが好ましい。しかし、薄膜状の場合には必ずしも
粒径にはこだわらず、比表面積で0.1〜5m2 /g、
好ましくは0.3〜3m2 /gの物性を有していること
が良い。In the present invention, the above metal silicon powder is
Direct nitridation reaction using copper or a mixture of copper compounds
But copper added as a catalyst to the metal silicon powder
Or, from the viewpoint of uniformity, the particle size of the copper compound
Particles of the same weight as the silicon particles
Preferably. However, in the case of a thin film,
Regardless of the particle size, 0.1 to 5m in specific surface areaTwo / G,
Preferably 0.3 to 3 mTwo / G physical properties
Is good.
【0019】なお、金属ケイ素に触媒として添加する銅
化合物は、弗化銅、酸化銅、塩化銅、その他の銅化合物
のいずれでも良く、特に限定されるものではない。しか
しながら、殆どの銅化合物は、融点が低く低温で分解
し、その際に生じる副生物が金属ケイ素を侵食し、不純
物として製造される窒化ケイ素中に残存し、窒化ケイ素
焼結体の強度を低下させるおそれがあるために、純度9
9%以上の金属銅を添加することが望ましい。また、銅
の形状についても特に限定されるものではなく、球状、
薄膜状、不定形等、市販されているもので良い。The copper compound added to the metal silicon as a catalyst may be any of copper fluoride, copper oxide, copper chloride and other copper compounds, and is not particularly limited. However, most copper compounds have a low melting point and decompose at low temperatures, and the by-products produced at that time erode metallic silicon and remain in silicon nitride produced as impurities, reducing the strength of the silicon nitride sintered body. Purity 9
It is desirable to add 9% or more of metallic copper. Also, the shape of the copper is not particularly limited, and may be spherical,
Commercially available materials such as a thin film and an amorphous shape may be used.
【0020】上記銅又は銅化合物の添加量は、原料金属
ケイ素に対して銅換算で0.05%以上0.5%未満、
特に0.1%〜0.4%が好ましい。添加量が0.05
%未満ではもはや添加の効果は認められず、また添加量
が0.5%以上では通常の精製処理をして得られる窒化
ケイ素粉末中には許容レベル以上の銅又は銅化合物が残
存するために当該金属ケイ素粉末を使用した焼結体の強
度に悪影響を及ぼし、本発明の目的を達成し得ない。The amount of the copper or copper compound added is 0.05% or more and less than 0.5% in terms of copper relative to the raw metal silicon;
In particular, 0.1% to 0.4% is preferable. 0.05 added
%, The effect of addition is no longer recognized. If the addition amount is 0.5% or more, copper or a copper compound at an allowable level or more remains in the silicon nitride powder obtained by the ordinary purification treatment because the amount of copper or copper compound remains. This has an adverse effect on the strength of the sintered body using the metal silicon powder, and the object of the present invention cannot be achieved.
【0021】ここで、本発明の第1発明では、金属ケイ
素粉末に銅又は銅化合物を混合度が0.9以上、より好
ましくは0.93以上、更に好ましくは0.95以上に
なるように混合することが必要であり、このように混合
度を0.9以上とすることにより、銅又は銅化合物の添
加量を0.5%未満の少量としてもその効果を達成する
ことが可能になるものである。これに対し、混合度が
0.9より小さいと、銅又は銅化合物の添加量を0.5
%以上としないとその効果が有効に達成されない。Here, in the first invention of the present invention, the mixing ratio of copper or a copper compound to the metallic silicon powder is adjusted to 0.9 or more, more preferably 0.93 or more, and still more preferably 0.95 or more. It is necessary to mix, and by setting the mixing degree to 0.9 or more as described above, the effect can be achieved even when the addition amount of copper or copper compound is as small as less than 0.5%. Things. On the other hand, when the mixing degree is smaller than 0.9, the addition amount of copper or copper compound is 0.5
If not, the effect cannot be effectively achieved.
【0022】なお、この混合度は、下記のRoseの式
から求めた値であり、混合を行うことで1に近づき、完
全混合状態(下記式でxi=x0の場合)で混合度は1で
ある。The degree of mixing is a value obtained from the following equation of Rose. The degree of mixing approaches 1 by performing mixing, and the degree of mixing is completely mixed (when x i = x 0 in the following equation). It is one.
【0023】[0023]
【数1】 (Equation 1)
【0024】この場合、上記Nの値(サンプル個数)
は、できるだけ多い方が正確な混合度を測定できるが、
本発明者の検討によればN≧20であれば有意差がない
ものであり、従って、本発明において、上記混合度は、
その混合物からスポットサンプリング法で棒状型又はミ
ゼットスプーン型サンプラーを用いて1〜50gのサン
プルを20個以上採取した場合(N≧20)の値を指
す。In this case, the value of N (the number of samples)
Means that as many as possible can measure the degree of mixing accurately,
According to the study of the present inventors, if N ≧ 20, there is no significant difference. Therefore, in the present invention, the mixing degree is
It indicates the value when 20 or more samples of 1 to 50 g are collected from the mixture by a spot sampling method using a rod type or a midget spoon type sampler (N ≧ 20).
【0025】本発明においては、金属ケイ素粉末に銅又
は銅化合物を混合し、均一分散させるものであるが、均
一混合させるための混合機としては、Vブレンダーのよ
うな容器回転型又はスクリュー型、高速剪断型のような
容器固定型の混合機が好適であるが、これに限定される
ものではない。In the present invention, copper or a copper compound is mixed with metal silicon powder and uniformly dispersed. As a mixer for uniform mixing, a container rotating type such as a V blender or a screw type is used. A fixed-type mixer such as a high-speed shearing type mixer is suitable, but not limited thereto.
【0026】このように銅又は銅化合物が均一混合、分
散されたままの金属ケイ素粉末は、特にトンネル炉形式
等の固定床形式の反応炉に対し好適に用いることがで
き、一度均一に混合された原料はかかる反応炉において
反応工程中もその状態を維持でき、良好な直接窒化反応
を行わせることができる。The metal silicon powder in which copper or copper compound is uniformly mixed and dispersed as described above can be suitably used particularly for a fixed-bed type reactor such as a tunnel furnace type. The raw material can maintain its state during the reaction process in such a reactor, and can perform a favorable direct nitriding reaction.
【0027】この場合、混合速度、混合時間等の混合条
件は、混合機の形状、大きさ及び操作条件(回転速度、
粉体装入率等)で大きく異なるが、例えば高速剪断型混
合機である20リットルヘンシェルミキサーを用いた場
合、粉体装入率30%、回転数1000rpmで30分
以上混合を行えば、上記混合度は通常0.9以上とな
る。In this case, the mixing conditions such as the mixing speed and the mixing time are determined by the shape, size and operating conditions of the mixer (rotational speed, mixing speed, etc.).
For example, when a 20-liter Henschel mixer, which is a high-speed shearing mixer, is used and the mixing is performed for 30 minutes or more at a powder charging rate of 30% and a rotation speed of 1000 rpm, The mixing degree is usually 0.9 or more.
【0028】これに対し、流動層や回転炉形式の反応器
の場合のように、原料が均一に混合されていても金属ケ
イ素と銅又は銅化合物の密度差や粒度の差で反応器の中
で分級を起こすおそれがある場合には、予め所定の混合
比率に調整され、混合度0.9以上とされた金属ケイ素
粉末と銅又は銅化合物とをポリビニルアルコール、メチ
ルセルロース、セルロース誘導体、でんぷん等の適当な
結合剤を用いて最適の大きさ、好ましくは100μm〜
30mmに成形させた成形物又は当該成形物を1,00
0〜1,400℃の温度範囲で不活性ガス雰囲気下、不
活性ガス雰囲気の減圧下、真空下などの不活性雰囲気下
で熱処理して得られる焼結体を反応原料として使用した
り(第2発明)、或いは所定の混合比率に調整された配
合物をいったん溶融させ、ケイ素−銅合金をつくった上
で、再度所定の粒度に粉砕したものを原料として用いる
(第3発明)ことが推奨される。なお、この第3発明の
場合は、必ずしも混合度を0.9以上としなくてもよ
い。On the other hand, even when the raw materials are uniformly mixed, as in the case of a fluidized bed or a rotary furnace type reactor, the difference in density and particle size between silicon metal and copper or a copper compound causes a difference in the reactor. If there is a risk of classification in the, it is adjusted to a predetermined mixing ratio in advance, the metal silicon powder and copper or copper compound with a mixing degree of 0.9 or more polyvinyl alcohol, methyl cellulose, cellulose derivative, starch and the like Optimum size using suitable binder, preferably 100 μm
A molded product molded to 30 mm or the molded product is
A sintered body obtained by heat treatment in an inert gas atmosphere in a temperature range of 0 to 1,400 ° C., under a reduced pressure of an inert gas atmosphere, or in an inert atmosphere such as a vacuum may be used as a reaction raw material. (2 invention), or it is recommended to once melt a compound adjusted to a predetermined mixing ratio to form a silicon-copper alloy and then pulverize it again to a predetermined particle size to use as a raw material (3rd invention). Is done. In the case of the third invention, the degree of mixing does not necessarily have to be 0.9 or more.
【0029】なお、前者の結合剤を用いる方法を採用す
る場合、結合剤を固形物換算で0.5〜10%、好まし
くは1〜3%添加・混合し、押出造粒機等の造粒成形機
を用いて、平均粒子径100μm〜30mm、好ましく
は300μm〜5mmに造粒した後、アルゴン、ヘリウ
ム等の不活性ガス雰囲気中常圧もしくは減圧(好ましく
は100Torr以下)で又は真空中で1,000〜
1,400℃、好ましくは1,200〜1,400℃で
ケイ素同士を軽度に融合させる程度に短時間焼結したも
のを使用することが好ましい。この場合、当該工程にお
いて、造粒時に添加されたポリビニルアルコール等の結
合剤は、除去される。When the former method using a binder is employed, the binder is added and mixed in an amount of 0.5 to 10%, preferably 1 to 3% in terms of solids, and the mixture is granulated by an extrusion granulator or the like. After granulating to an average particle diameter of 100 μm to 30 mm, preferably 300 μm to 5 mm using a molding machine, the mixture is subjected to atmospheric or reduced pressure (preferably 100 Torr or less) in an inert gas atmosphere such as argon or helium, or 000 ~
It is preferable to use a material which is sintered at 1,400 ° C., preferably 1,200 to 1,400 ° C., for a short time so that silicon is slightly fused. In this case, in this step, a binder such as polyvinyl alcohol added during granulation is removed.
【0030】更に、当該方法は造粒物に限定されるもの
ではなく、同様の処方でスクリュータイプや油圧タイプ
の押出成形機を用いて、棒状、ブロック状、球状の成形
物にした後、上記記載の方法で、前処理し、トンネル炉
等の固定床炉を用いて窒化させる場合にも有効な方法で
ある。なお、このように成形物を用いて窒化を行った場
合、窒化後に適宜な粒径に粉砕し、窒化ケイ素粉末を得
る。Further, the method is not limited to the granulated product, but is formed into a rod-shaped, block-shaped or spherical shaped product using a screw type or hydraulic type extruder with the same prescription. It is also an effective method when pretreating by the method described and nitriding using a fixed-bed furnace such as a tunnel furnace. In the case where nitriding is performed using the molded product as described above, the powder is ground to an appropriate particle size after nitriding to obtain a silicon nitride powder.
【0031】本発明の高α型窒化ケイ素粉末の製造方法
は、上記の金属ケイ素と銅又は銅化合物との均一混合物
を直接窒化法の通常の方法に従い、窒素又はアンモニア
を含む非酸化性ガス雰囲気下、1,000〜1,500
℃の温度範囲で窒化反応を行わせ、高α型窒化ケイ素粉
末を製造するものである。なお、非酸化性ガスは、窒素
単独か窒素とアンモニア、アルゴン、ヘリウム、水素ガ
スの少なくとも1種以上との混合ガスのいずれを用いる
こともできる。The method for producing a high α-type silicon nitride powder according to the present invention comprises the steps of directly nitriding the homogeneous mixture of metallic silicon and copper or a copper compound according to an ordinary method of nitriding, in a non-oxidizing gas atmosphere containing nitrogen or ammonia. Bottom, 1,000-1,500
The nitriding reaction is carried out in a temperature range of ° C. to produce a high α-type silicon nitride powder. As the non-oxidizing gas, either nitrogen alone or a mixed gas of nitrogen and at least one of ammonia, argon, helium, and hydrogen gas can be used.
【0032】以上のようにして得られる窒化ケイ素粉末
は、通常α化率90%以上、特に92%以上のものであ
る。The silicon nitride powder obtained as described above usually has an α conversion of 90% or more, particularly 92% or more.
【0033】なお、得られた窒化ケイ素粉末は、塩酸、
硝酸、弗酸等の酸を用い、常温〜80℃で10分〜3時
間処理した後、常法に従って水洗、乾燥することが好ま
しく、上記酸処理により窒化ケイ素粉末中の主として
鉄、酸素、未反応金属ケイ素等の不純物、更に触媒とし
て用いた銅又は銅化合物が除去されて、高純度の窒化ケ
イ素粉末を得ることができる。この場合、上記酸処理で
窒化ケイ素粉末中の銅分は5ppm以下に低減し、この
ような高純度の窒化ケイ素粉末を用いることにより、常
温焼結強度が900MPa以上の窒化ケイ素焼結体を得
ることができる。The obtained silicon nitride powder was prepared by adding hydrochloric acid,
After treating with an acid such as nitric acid or hydrofluoric acid at room temperature to 80 ° C. for 10 minutes to 3 hours, it is preferable to wash and dry with a conventional method. The impurities such as reactive metal silicon and the copper or copper compound used as the catalyst are removed, so that a high-purity silicon nitride powder can be obtained. In this case, the copper content in the silicon nitride powder is reduced to 5 ppm or less by the acid treatment, and a silicon nitride sintered body having a normal temperature sintering strength of 900 MPa or more is obtained by using such a high-purity silicon nitride powder. be able to.
【0034】[0034]
【発明の効果】本発明によれば、原料金属ケイ素に微量
の銅又は銅化合物を触媒として添加することにより、α
化率の高い窒化ケイ素粉末を容易かつ安定的に製造で
き、しかも通常の酸処理で銅や銅化合物を効率よく除去
し得て、高純度の焼結体を与える窒化ケイ素粉末を効率
よく低コストで得ることができ、工業的規模の生産にお
いても十分に適用し得るものである。According to the present invention, α is obtained by adding a trace amount of copper or a copper compound as a catalyst to raw metal silicon.
Silicon nitride powder with high conversion rate can be easily and stably manufactured, and copper and copper compounds can be efficiently removed by ordinary acid treatment, and silicon nitride powder that gives a high-purity sintered body can be efficiently manufactured at low cost. And can be sufficiently applied to production on an industrial scale.
【0035】[0035]
【実施例】以下、実施例と比較例を示し、本発明を具体
的に説明するが、本発明は下記の実施例に制限されるも
のではない。EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.
【0036】〔実施例1〜2、比較例1〜7〕平均粒子
径2〜3μmの金属ケイ素粉末に平均粒子径35μm
(比表面積0.4m2/g)の銅を表1に示す割合で添
加し、20リットルヘンシェルミキサーを用い、粉体装
入率30%、回転数1000rpmで表1に示す時間混
合を行った。その後、この混合物をミゼットスプーンを
用い、3gづつスポットサンプリング法にてN=30個
サンプリングを行い、上記Roseの式より混合度を求
めた。[Examples 1 and 2, Comparative Examples 1 to 7] Metal silicon powder having an average particle size of 2 to 3 μm was added to an average particle size of 35 μm.
Copper (specific surface area: 0.4 m 2 / g) was added at the ratio shown in Table 1 and mixed for 20 hours using a 20-liter Henschel mixer at a powder loading rate of 30% and a rotation speed of 1,000 rpm for the time shown in Table 1. . Thereafter, using a midget spoon, the mixture was sampled by N = 30 samples by the spot sampling method for each 3 g, and the degree of mixing was determined from the above Rose equation.
【0037】次に、当該混合物を窒化ケイ素製トレイに
200g仕込み、窒素ガス/水素ガス=容量比4/1の
混合ガスを流入させながら、中心反応温度1,300℃
に加熱保持して窒化反応を行わせた。得られた窒化ケイ
素については、X線回折分析を行い、α化率及び反応率
を求めた。Next, 200 g of the mixture was charged into a silicon nitride tray, and a central reaction temperature of 1,300 ° C. was introduced while flowing a mixed gas of nitrogen gas / hydrogen gas = 4/1 by volume.
And a nitriding reaction was carried out. The obtained silicon nitride was subjected to X-ray diffraction analysis to determine the α conversion and the reaction rate.
【0038】更に、このようにして得られた反応生成物
を5リットル湿式粉砕機を用いて平均粒子径0.4〜
0.5μmに粉砕した後、当該スラリーに弗酸及び硝酸
を各々200g加え、80℃で1時間の酸処理を行っ
た。その後、水洗・乾燥を経て製品を得た。この製品に
つき、ICP発光分析法による残存Cu率の測定、常温
での三点曲げ強度測定を行った。Further, the reaction product thus obtained was subjected to a 5 liter wet pulverizer to obtain an average particle diameter of 0.4 to 4.5.
After pulverization to 0.5 μm, 200 g of each of hydrofluoric acid and nitric acid was added to the slurry, and an acid treatment was performed at 80 ° C. for 1 hour. Thereafter, the product was obtained through washing and drying. For this product, the residual Cu ratio was measured by ICP emission spectrometry, and the three-point bending strength at room temperature was measured.
【0039】また、比較のために銅無添加のものを同条
件下で製品化した。以上の結果及び各条件を表1に示
す。For comparison, a product without copper was commercialized under the same conditions. Table 1 shows the above results and each condition.
【0040】[0040]
【表1】 [Table 1]
【0041】〔実施例3、比較例8〜11〕上記実施
例、比較例と同様の金属ケイ素原料に表2に示す量で銅
を添加し、60分間混合して混合度を0.9以上とした
混合物にポリビニルアルコール水溶液を固形物換算で1
重量%添加・混練し、造粒機で平均粒子径0.5mmに
造粒・成形した。これを150℃で1時間乾燥し、水分
を除去した後、アルゴンガス流通下100mmHg、
1,200℃で1時間処理し、焼結させたものを原料と
した。当該造粒粉末をロータリーキルンに100g/時
間で供給し、窒素ガス/水素ガス=4の混合ガスを流通
下、1,300℃で窒化反応を行わせた。その後、上記
実施例、比較例に示された方法で処理をした。また、比
較のために銅無添加のものを同条件下で製品化した。以
上の結果及び各条件を表2に示す。なお、上記のように
造粒成形せずにロータリーキルンに供給した場合は、キ
ルンの途中で凝集し、反応を継続させることができなか
った。Example 3, Comparative Examples 8 to 11 Copper was added to the same metallic silicon raw material as in the above Examples and Comparative Examples in the amount shown in Table 2, and mixed for 60 minutes to increase the degree of mixing to 0.9 or more. Aqueous solution of polyvinyl alcohol was added to
% By weight, kneaded, and granulated and molded to an average particle diameter of 0.5 mm with a granulator. This was dried at 150 ° C. for 1 hour to remove water, and then 100 mmHg under flowing argon gas.
A material treated at 1,200 ° C. for 1 hour and sintered was used as a raw material. The granulated powder was supplied to a rotary kiln at a rate of 100 g / hour, and a nitriding reaction was performed at 1,300 ° C. while flowing a mixed gas of nitrogen gas / hydrogen gas = 4. Thereafter, the treatment was carried out by the methods shown in the above Examples and Comparative Examples. For comparison, a product without copper was commercialized under the same conditions. Table 2 shows the above results and each condition. In addition, when it supplied to the rotary kiln without performing granulation molding as mentioned above, it aggregated in the middle of the kiln and the reaction could not be continued.
【0042】[0042]
【表2】 [Table 2]
【0043】〔実施例4〕金属ケイ素1kg、銅3g
を、坩堝内で1,600℃に溶融混合させた後、冷却
し、平均粒子径2〜3μmの粉末に粉砕した。当該混合
物を窒化ケイ素製トレイに200g仕込み、窒素ガス/
水素ガス=4の混合ガスを流入させながら中心温度を
1,350℃に加熱保持して窒化反応を行わせた。以
後、実施例3と同様の処理を行った。得られた窒化ケイ
素粉末のα化率は94.3%、反応率は98.5%、残
存銅の含有量は5ppm以下、焼結成形体の三点曲げ強
度は950MPaであった。Example 4 1 kg of metallic silicon and 3 g of copper
Was melted and mixed at 1600 ° C. in a crucible, cooled, and pulverized into a powder having an average particle diameter of 2 to 3 μm. 200 g of the mixture was placed in a silicon nitride tray, and nitrogen gas /
The nitriding reaction was performed by heating and maintaining the central temperature at 1,350 ° C. while flowing a mixed gas of hydrogen gas = 4. Thereafter, the same processing as in Example 3 was performed. The α-rate of the obtained silicon nitride powder was 94.3%, the reaction rate was 98.5%, the content of residual copper was 5 ppm or less, and the three-point bending strength of the sintered compact was 950 MPa.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 渡辺 真樹 群馬県安中市磯部2丁目13番1号 信越 化学工業株式会社 群馬事業所内 (56)参考文献 特開 昭57−188465(JP,A) (58)調査した分野(Int.Cl.6,DB名) C01B 21/068 C04B 35/626 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Maki Watanabe 2-3-1-1, Isobe, Annaka-shi, Gunma Shin-Etsu Chemical Co., Ltd. Gunma Office (56) References JP-A-57-188465 (JP, A) (58) Field surveyed (Int. Cl. 6 , DB name) C01B 21/068 C04B 35/626
Claims (3)
くとも一種を金属ケイ素に対して銅換算で0.05重量
%以上0.5重量%未満添加し、混合度が0.9以上と
なるように混合し、該混合物を窒素又はアンモニアを含
む非酸化性ガス雰囲気中で1,000〜1,500℃の
温度範囲にて窒化することを特徴とする高α型窒化ケイ
素粉末の製造方法。At least one kind of copper or a copper compound is added to metallic silicon powder in an amount of 0.05% by weight or more and less than 0.5% by weight in terms of copper with respect to metallic silicon so that the degree of mixing is 0.9 or more. And nitriding the mixture in a non-oxidizing gas atmosphere containing nitrogen or ammonia at a temperature in the range of 1,000 to 1,500 ° C. to produce a high α-type silicon nitride powder.
くとも一種を金属ケイ素に対して銅換算で0.05重量
%以上0.5重量%未満添加し、混合度が0.9以上と
なるように混合し、該混合物を結合剤を用いて成形した
成形物又はこの成形物を不活性雰囲気中常圧もしくは減
圧で又は真空中で焼結した焼結物を窒素又はアンモニア
を含む非酸化性ガス雰囲気中で1,000〜1,500
℃の温度範囲にて窒化することを特徴とする高α型窒化
ケイ素粉末の製造方法。2. At least one kind of copper or a copper compound is added to metal silicon powder in an amount of 0.05% by weight or more and less than 0.5% by weight in terms of copper with respect to metal silicon so that the mixing degree becomes 0.9 or more. And a molded product obtained by molding the mixture using a binder, or a sintered product obtained by sintering the molded product in an inert atmosphere at normal pressure or reduced pressure or in a vacuum is a non-oxidizing gas atmosphere containing nitrogen or ammonia. 1,000 to 1,500
A method for producing a high α-type silicon nitride powder, comprising nitriding in a temperature range of ° C.
くとも一種を金属ケイ素に対して銅換算で0.05重量
%以上0.5重量%未満配合・溶融させてケイ素−銅合
金を作った後、再度所定の粒度に粉砕した粉砕物を窒素
又はアンモニアを含む非酸化性ガス雰囲気中で1,00
0〜1,500℃の温度範囲にて窒化することを特徴と
する高α型窒化ケイ素粉末の製造方法。3. A silicon-copper alloy is prepared by blending and melting at least one of copper or a copper compound with metal silicon powder with respect to metal silicon in an amount of 0.05% by weight or more and less than 0.5% by weight in terms of copper. Then, the pulverized product which has been pulverized again to a predetermined particle size is placed in a non-oxidizing gas atmosphere containing nitrogen or ammonia for 1,000 hours.
A method for producing a high α-type silicon nitride powder, comprising nitriding in a temperature range of 0 to 1,500 ° C.
Priority Applications (1)
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JP6120674A JP2970400B2 (en) | 1993-06-11 | 1994-05-10 | Method for producing high α-type silicon nitride powder |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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JP16618393 | 1993-06-11 | ||
JP5-166183 | 1993-06-11 | ||
JP6120674A JP2970400B2 (en) | 1993-06-11 | 1994-05-10 | Method for producing high α-type silicon nitride powder |
Publications (2)
Publication Number | Publication Date |
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JPH0753203A JPH0753203A (en) | 1995-02-28 |
JP2970400B2 true JP2970400B2 (en) | 1999-11-02 |
Family
ID=26458202
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JP6120674A Expired - Fee Related JP2970400B2 (en) | 1993-06-11 | 1994-05-10 | Method for producing high α-type silicon nitride powder |
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JP (1) | JP2970400B2 (en) |
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JP7240800B2 (en) * | 2015-12-24 | 2023-03-16 | エルジー・ケム・リミテッド | Method for producing α-silicon nitride |
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