JPH05148029A - Production of composite ceramic material - Google Patents

Abstract

PURPOSE:To produce a composite ceramic material having high strength and high toughness. CONSTITUTION:A composite ceramic material is produced by subjecting a powdery mixture composed mainly of alpha-silicon nitride powder and beta-silicon carbide powder to the primary sintering and then to the secondary sintering at a temperature higher than the primary sintering temperature under a nitrogen partial pressure higher than the nitrogen partial pressure in the primary sintering step. In the above process, the sum of the total impurity oxygen in the alpha-silicon nitride powder and the beta-silicon carbide powder is adjusted to 1.0-1.5wt.%, the total impurity carbon content is adjusted to 0.25-0.40wt.% and the length of the matrix silicon nitride in the direction of the major diameter is made to be <=11.0mum.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、各種機械構造物の素材
として用いられるセラミックス素材を製造するのに利用
されるセラミックス複合材料の製造方法に関するもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a ceramic composite material used for producing a ceramic material used as a material for various mechanical structures.

【０００２】[0002]

【従来の技術】炭化珪素（ＳｉＣ）と窒化珪素（Ｓｉ_３
Ｎ_４）を主体とする従来のセラミックス複合材料として
は、例えば、１０〜７２体積％のＳｉＣと５〜６５体積
％のＳｉ_３Ｎ_４と５〜４０体積％のＳｉとからなる複合
焼結体（特開昭６１−３６１７６号公報）や、ＳｉＣと
Ｓｉ_３Ｎ_４を主体とし且つ０．０５〜５０重量％の希土
類酸化物を添加して焼結した複合焼結体（特開昭６０−
４６９７３号公報）や、ＳｉＣとＳｉ_３Ｎ_４との混合粉
末に周期律表第ＩＩ，ＩＩＩ，ＩＶ族の金属およびこれ
らの酸・炭化物を混合して焼結した複合焼結体（特開昭
５８−９１０７０号公報）などが国内特許公開公報に開
示されたものとしてあり、そのほか、外国文献に示され
たものとして、Ｊｏｕｒｎａｌ ｏｆ Ａｍｅｒｉｃａ
ｎ Ｃｅｒａｍｉｃ Ｓｏｃｉｅｔｙ ５６（９）４４
５（１９７３）ではランゲが、また同じく６３（９−１
０）５９７（１９８０）ではグレスコビッチがそれぞれ
炭化珪素・窒化珪素質複合焼結体の機械的特性について
報告したものがある。2. Description of the Related Art Silicon carbide (SiC) and silicon nitride (Si ₃
As a conventional ceramic composite material mainly composed of N ₄ ), for example, a composite sintered body composed of 10 to 72% by volume of SiC, 5 to 65% by volume of Si ₃ N ₄ and 5 to 40% by volume of Si. (JP-A-61-36176) or a composite sintered body composed mainly of SiC and Si ₃ N ₄ and added with 0.05 to 50% by weight of a rare earth oxide (JP-A-60-36).
No. 46973) or a mixed powder of SiC and Si ₃ N ₄ mixed with a metal of Group II, III or IV of the periodic table and an acid / carbide thereof and sintered (Japanese Patent Application Laid-Open No. S60-12069). No. 58-91070), etc. are disclosed in the domestic patent publications, and in addition, as those disclosed in foreign documents, Journal of America is disclosed.
n Ceramic Society 56 (9) 44
In 5 (1973), Lange again, 63 (9-1)
0) 597 (1980), each reported by Grescovich on the mechanical properties of a silicon carbide / silicon nitride composite sintered body.

【０００３】また、他のセラミックス複合材料として、
有機珪素化合物から気相法で混合粉末を作製したのちホ
ットプレスして製造した複合焼結体（特開平１−２７５
４７０号公報）もあった。As another ceramic composite material,
A composite sintered body produced by hot pressing after producing a mixed powder from an organosilicon compound by a vapor phase method (JP-A-1-275).
470).

【０００４】さらに、常圧焼結により製造するセラミッ
クス複合材料として、窒化珪素が針状のβ相からなって
いると共に炭化珪素が単結晶であってかつ粒子径が２〜
３０μｍである複合焼結体（特開昭６４−９８７２号公
報）もあった。Further, as a ceramic composite material produced by pressureless sintering, silicon nitride is composed of needle-like β phase, silicon carbide is a single crystal and has a particle diameter of 2 to 2.
There was also a composite sintered body having a size of 30 μm (Japanese Patent Laid-Open No. 64-9872).

【０００５】[0005]

【発明が解決しようとする課題】しかしながら、上記し
たような従来のセラミックス複合材料にあっては、それ
らの多くが焼結時において緻密化を促進するためにホッ
トプレスを採用する必要があることから、複雑形状の部
品を製造することが困難であるという問題点を有してお
り、このような問題点を解決することが課題となってい
た。However, in most of the above-mentioned conventional ceramic composite materials, it is necessary to employ hot pressing in order to promote densification during sintering. However, there is a problem that it is difficult to manufacture a component having a complicated shape, and it has been a problem to solve such a problem.

【０００６】[0006]

【発明の目的】本発明は、上記したような従来の課題に
かんがみてなされたもので、ホットプレスによらずとも
高強度でかつ高靭性のセラミックス複合材料を得ること
が可能であるセラミックス複合材料の製造方法を提供す
ることを目的としている。SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and it is possible to obtain a ceramic composite material having high strength and high toughness without using hot pressing. It is intended to provide a manufacturing method of.

【０００７】[0007]

【課題を解決するための手段】本発明に係わるセラミッ
クス複合材料の製造方法は、α型窒化珪素粉末とβ型炭
化珪素粉末を主体とする混合粉末を１次焼結した後、１
次焼結温度よりも高温でかつ１次焼結窒素分圧よりも高
窒素分圧で２次焼結を行なってセラミックス複合材料を
製造するに際し、α型窒化珪素粉末とβ型炭化珪素粉末
の不純物酸素量の和を１．０〜１．５重量％の範囲にす
ると共に不純物炭素量の和を０．２５〜０．４０重量％
の範囲とし、マトリックス窒化珪素の長径方向の長さを
１１．０μｍ以下とした構成としたことを特徴としてお
り、このようなセラミックス複合材料の製造方法に係わ
る発明の構成をもって前述した従来の課題を解決するた
めの手段としている。The method for producing a ceramics composite material according to the present invention comprises first sintering a mixed powder mainly containing α-type silicon nitride powder and β-type silicon carbide powder, and then
When the secondary sintering is performed at a temperature higher than the secondary sintering temperature and a nitrogen partial pressure higher than the primary sintering nitrogen partial pressure to produce a ceramic composite material, α-type silicon nitride powder and β-type silicon carbide powder The sum of the amount of impurity oxygen is in the range of 1.0 to 1.5% by weight, and the sum of the amount of impurity carbon is 0.25 to 0.40% by weight.
And the length of the matrix silicon nitride in the major axis direction is set to 11.0 μm or less, and the conventional problems described above with the configuration of the invention related to the method for producing such a ceramic composite material are It is taken as a means to solve it.

【０００８】本発明に係わるセラミックス複合材料の製
造方法の実施態様においては、α型窒化珪素粉末とβ型
炭化珪素粉末を主体とする混合粉末を１〜２気圧の窒素
分圧下で１次焼結した後、次いで１次焼結温度よりも１
００〜２００℃高い温度でかつ１次焼結窒素分圧よりも
高窒素分圧である１０〜２０００気圧の窒素分圧下で２
次焼結を行なってセラミックス複合材料を製造するに際
し、主成分であるα型窒化珪素粉末とβ型炭化珪素粉末
の不純物酸素量の和を１．０〜１．５重量％の範囲にす
ると共に不純物炭素量の和を０．２５〜０．４０重量％
の範囲として、１次の焼結時に微細なβ型窒化珪素を析
出させると共に２次の加圧焼結時に有効な密度まで緻密
化させることによって、高強度でかつ高靭性のセラミッ
クス複合材料とする。In an embodiment of the method for producing a ceramic composite material according to the present invention, a mixed powder mainly containing α-type silicon nitride powder and β-type silicon carbide powder is subjected to primary sintering under a nitrogen partial pressure of 1 to 2 atmospheres. And then 1 more than the primary sintering temperature
2 at a high temperature of 0 to 200 ° C. and a nitrogen partial pressure of 10 to 2000 atm, which is a nitrogen partial pressure higher than the primary sintering nitrogen partial pressure.
During the subsequent sintering to produce a ceramic composite material, the sum of the amounts of impurity oxygen of the α-type silicon nitride powder and the β-type silicon carbide powder, which are the main components, is set to 1.0 to 1.5% by weight. 0.25 to 0.40% by weight of the sum of impurity carbon
In this range, fine β-type silicon nitride is precipitated during the primary sintering and is densified to an effective density during the secondary pressure sintering to obtain a ceramic composite material having high strength and high toughness. ..

【０００９】本発明に係わるセラミックス複合材料の製
造方法においては、α型窒化珪素粉末とβ型炭化珪素粉
末を主体とし、その他焼結助剤を含む混合粉末を用いる
ようにしているが、この場合の混合粉末組成としては、
α型窒化珪素粉末を９５〜７０重量％と、β型炭化珪素
粉末を５〜３０重量％と、焼結助剤としてＹ_２Ｏ_３，Ａ
ｌ_２Ｏ_３等の各種の酸化物などを５〜２０重量％含むも
のが使用される。In the method for manufacturing a ceramic composite material according to the present invention, a mixed powder containing α-type silicon nitride powder and β-type silicon carbide powder as the main component and other sintering aids is used. The mixed powder composition of
95-70% by weight of α-type silicon nitride powder, 5-30% by weight of β-type silicon carbide powder, and Y ₂ O ₃ , A as a sintering aid.
Those containing 5 to 20% by weight of various oxides such as ₁₂ O ₃ are used.

【００１０】この場合、焼結助剤は焼結時に高温で粒界
ガラス層となり、焼結性に大きく影響するが、窒化珪素
のα→β転移とその後の粒成長を支配する成分は、窒化
珪素と炭化珪素の粒子表面に存在する不純物酸素と不純
物炭素である。In this case, the sintering aid forms a grain boundary glass layer at a high temperature during sintering and greatly affects the sinterability. However, the component that controls the α → β transition of silicon nitride and the subsequent grain growth is nitriding. Impurity oxygen and impurity carbon existing on the surface of particles of silicon and silicon carbide.

【００１１】そして、不純物酸素の量が多いときには窒
化珪素のα→β転移を促進して粒成長を起こしやすく、
酸素量の下限は１次焼結によって密度が理論密度の９５
％以上となるように１．０重量％以上とするのが良い
が、不純物酸素の量が１．５重量％を超えるような過度
の酸素は粗大粒子を成長させ、強度が向上しがたくな
る。したがって、α型窒化珪素粉末とβ型炭化珪素粉末
の不純物酸素の和が１．０〜１．５重量％の範囲とする
のが良い。When the amount of impurity oxygen is large, the α → β transition of silicon nitride is promoted to easily cause grain growth,
The lower limit of the oxygen content is 95% of the theoretical density due to the primary sintering.
%, Preferably 1.0% by weight or more, but excessive oxygen such that the amount of impurity oxygen exceeds 1.5% by weight causes coarse particles to grow, making it difficult to improve strength. .. Therefore, the sum of the impurity oxygen in the α-type silicon nitride powder and the β-type silicon carbide powder is preferably in the range of 1.0 to 1.5% by weight.

【００１２】一方、不純物炭素は窒化珪素の焼結を阻害
するので少ない方が良いが、あまりに少なすぎると粗大
粒子の成長を生じることから０．２５重量％以上とする
のが良く、反対に多すぎると焼結が進行しなくなるの
で、α型窒化珪素粉末とβ型炭化珪素粉末の不純物炭素
の和が０．２５〜０．４０重量％の範囲とするのが良
い。On the other hand, it is preferable that the amount of impurity carbon is small because it impedes the sintering of silicon nitride, but if it is too small, the growth of coarse particles will occur, so it is preferable to set it to 0.25% by weight or more. If it is too much, sintering will not proceed, so the sum of the impurity carbons of the α-type silicon nitride powder and the β-type silicon carbide powder is preferably in the range of 0.25 to 0.40% by weight.

【００１３】このように、本発明においては、混合粉末
の不純物酸素および不純物炭素を制御することによっ
て、１次焼結において窒化珪素のα→β転移を最小限の
粒成長に抑え、２次焼結が可能である最小の密度に抑え
ることによって、２次焼結による焼結粒を小さくして、
高強度でかつ高靭性のセラミックス複合材料が得られる
ようにしているが、さらに、マトリックス窒化珪素の長
径方向の長さが大きすぎると強度が低下するので、長径
方向の大きさは１１．０μｍ以下とする必要がある。As described above, in the present invention, by controlling the impurity oxygen and the impurity carbon of the mixed powder, the α → β transition of silicon nitride is suppressed to the minimum grain growth in the primary sintering, and the secondary firing is performed. By suppressing the density to the minimum that can be bonded, the size of the sintered particles due to secondary sintering is reduced,
Although a ceramic composite material having high strength and high toughness is obtained, further, if the length of the matrix silicon nitride in the major axis direction is too large, the strength lowers. Therefore, the size in the major axis direction is 11.0 μm or less. And need to.

【００１４】[0014]

【発明の作用】本発明に係わるセラミックス複合材料の
製造方法によれば、α型窒化珪素粉末とβ型炭化珪素粉
末を主体とする混合粉末を１次焼結した後、１次焼結温
度よりも高温でかつ１次焼結窒素分圧よりも高窒素分圧
で２次焼結を行なってセラミックス複合材料を製造する
に際し、前記α型窒化珪素粉末とβ型炭化珪素粉末の不
純物酸素の和および不純物炭素の和を制御するようにし
ているので、１次焼結において窒化珪素のα→β転移が
最小限の粒成長に抑制されると共に２次焼結のできる最
小の密度に抑制されることによって２次焼結により結晶
粒が小さなものとなることから、高強度でかつ高靭性の
セラミックス複合材料が製造されるものとなる。According to the method for producing a ceramics composite material of the present invention, the mixed powder mainly containing α-type silicon nitride powder and β-type silicon carbide powder is subjected to primary sintering and then the temperature is changed from the primary sintering temperature. In producing a ceramic composite material by performing secondary sintering at a high temperature and a nitrogen partial pressure higher than the primary sintering nitrogen partial pressure, the sum of impurity oxygen of the α-type silicon nitride powder and β-type silicon carbide powder is Since the sum of carbon and impurity carbon is controlled, the α → β transition of silicon nitride is suppressed to the minimum grain growth in the primary sintering and to the minimum density capable of the secondary sintering. As a result, the crystal grain becomes small due to the secondary sintering, so that a ceramic composite material having high strength and high toughness can be manufactured.

【００１５】[0015]

【実施例】表１に示すように、α型窒化珪素（α−Ｓｉ
_３Ｎ_４）粉末が７７．３重量％と、β型炭化珪素（β−
ＳｉＣ）粉末が９．１重量％と、焼結助剤（Ｙ_２Ｏ_３＋
Ａｌ_２Ｏ_３、ただし、Ｙ_２Ｏ_３：Ａｌ_２Ｏ_３＝２：１）
が１３．６重量％よりなる混合粉末を用意し、この際、
α型窒化珪素粉末とβ型炭化珪素粉末の不純物酸素量お
よび不純物炭素量を同じく表１に示す値に制御した混合
粉末を用いた。EXAMPLES As shown in Table 1, α-type silicon nitride (α-Si
₃ N ₄ ) powder was 77.3% by weight, and β-type silicon carbide (β-
9.1% by weight of SiC powder and sintering aid (Y ₂ O ₃ +
Al ₂ O ₃ , provided that Y ₂ O ₃ : Al ₂ O ₃ = 2: 1)
A mixed powder of 13.6% by weight is prepared.
A mixed powder in which the amounts of impurity oxygen and the amount of impurity carbon of the α-type silicon nitride powder and the β-type silicon carbide powder were controlled to the values shown in Table 1 was used.

【００１６】次いで、前記混合粉末を冷間等方圧加圧
（ＣＩＰ；圧縮圧力４ｔｏｎ）により成形したのち、同
じく表１に示す条件によりＮ_２ガス雰囲気中で常圧によ
り１次焼結し、続いて、同じく表１に示すように、前記
１次焼結温度よりも１００℃高温でかつ１次焼結窒素分
圧よりも高窒素分圧でより長時間の条件で２次焼結（再
焼結）を行なって、各々セラミックス複合材料を得た。Next, the mixed powder was compacted by cold isostatic pressing (CIP; compression pressure 4 ton) and then primary-sintered under normal pressure in N ₂ gas atmosphere under the same conditions as shown in Table 1, Then, as also shown in Table 1, the secondary sintering (re- sintering) was performed at a temperature 100 ° C. higher than the primary sintering temperature and a nitrogen partial pressure higher than the primary sintering nitrogen partial pressure for a longer time. Sintering) was performed to obtain ceramic composite materials.

【００１７】次に、このようにして得た各セラミックス
複合材料の密度，曲げ強度，破壊靭性，硬さを調べると
共に、マトリックス窒化珪素の最大粒径を調べたとこ
ろ、表２に示す結果であった。Next, the density, bending strength, fracture toughness, and hardness of each ceramic composite material thus obtained were examined, and the maximum grain size of the matrix silicon nitride was examined. The results are shown in Table 2. It was

【００１８】[0018]

【表１】 [Table 1]

【００１９】[0019]

【表２】 [Table 2]

【００２０】表２に示した結果より明らかなように、α
型窒化珪素粉末とβ型炭化珪素粉末における不純物酸素
の和を１．０〜１．５重量％の範囲内である１．１７〜
１．４２重量％とすると共に不純物炭素の和を０．２５
〜０．４０重量％の範囲内である０．２６〜０．３１重
量％とし、マトリックス窒化珪素の最大粒径が１１．０
μｍ以下である７．０〜１１．０μｍとした本発明実施
例１，２，３の場合には、１次焼結時において１次焼結
体の窒化珪素の焼結を抑制して粒成長を抑え、その後２
次焼結で緻密化するものとなることから、密度が高く曲
げ強度が大であると共に破壊靭性が良好な値を示してお
り、曲げ強度が１０００ＭＰａ以上の高強度でかつ高靭
性のセラミックス複合材料となっていることが認められ
た。As is clear from the results shown in Table 2, α
Of the sum of impurity oxygen in the β-type silicon nitride powder and the β-type silicon carbide powder is in the range of 1.0 to 1.5% by weight, 1.17 to
1.42 wt% and the sum of carbon impurities is 0.25
The maximum grain size of the matrix silicon nitride is 11.0.
In the case of Examples 1, 2, and 3 of the present invention in which the thickness is 7.0 μm to 11.0 μm, the grain growth is suppressed by suppressing the sintering of silicon nitride of the primary sintered body during the primary sintering. Hold, then 2
Since it will be densified by the subsequent sintering, it has a high density, a large bending strength, and a good fracture toughness value, and has a high bending strength of 1000 MPa or more and a high toughness ceramic composite material. It was confirmed that

【００２１】これに対して、α型窒化珪素粉末とβ型炭
化珪素粉末における不純物酸素の和が１．５重量％より
も多いと共に不純物炭素の和が０．２５重量％よりも少
なく、マトリックス窒化珪素の最大粒径が１１．０μｍ
よりも大きい比較例１，２，３の場合には、密度は高い
ものの曲げ強度が低く、破壊靭性にも劣るものとなって
いた。On the other hand, the sum of the impurity oxygen in the α-type silicon nitride powder and the β-type silicon carbide powder is more than 1.5% by weight and the sum of the impurity carbon is less than 0.25% by weight. Maximum grain size of silicon is 11.0 μm
In Comparative Examples 1, 2, and 3, which were larger than the above, the bending strength was low and the fracture toughness was poor although the density was high.

【００２２】[0022]

【発明の効果】本発明に係わるセラミックス複合材料の
製造方法では、α型窒化珪素粉末とβ型炭化珪素粉末を
主体とする混合粉末を１次焼結した後、１次焼結温度よ
りも高温でかつ１次焼結窒素分圧よりも高窒素分圧で２
次焼結を行なってセラミックス複合材料を製造するに際
し、α型窒化珪素粉末とβ型炭化珪素粉末の不純物酸素
量の和を１．０〜１．５重量％の範囲にすると共に不純
物炭素量の和を０．２５〜０．４０重量％の範囲とし、
マトリックス窒化珪素の長径方向の長さを１１．０μｍ
以下とした構成としたから、１次焼結時において窒化珪
素の焼結を抑えて粒成長を抑制した後、２次焼結時にお
いて緻密化したものとなり、曲げ強度が１０００ＭＰａ
以上の高強度でかつ高靭性のセラミックス複合材料を得
ることが可能になって、セラミックス製構造部材の高強
度・高靭性化が可能であり、さらにはホットプレスによ
らずとも良いため複雑形状のセラミックス製構造部材を
製造することが可能になるという著しく優れた効果がも
たらされる。In the method for manufacturing a ceramic composite material according to the present invention, the mixed powder mainly containing α-type silicon nitride powder and β-type silicon carbide powder is primarily sintered and then heated to a temperature higher than the primary sintering temperature. And a nitrogen partial pressure higher than the primary sintered nitrogen partial pressure is 2
When manufacturing the ceramic composite material by performing the subsequent sintering, the sum of the impurity oxygen amounts of the α-type silicon nitride powder and the β-type silicon carbide powder is set to the range of 1.0 to 1.5% by weight, and The sum is in the range of 0.25 to 0.40% by weight,
The length of the matrix silicon nitride in the major axis direction is 11.0 μm.
Because of the following configuration, the sintering of silicon nitride is suppressed during the primary sintering to suppress the grain growth, and then the densification is performed during the secondary sintering, and the bending strength is 1000 MPa.
It is possible to obtain a ceramic composite material with high strength and high toughness as described above, and it is possible to increase the strength and toughness of the ceramic structural member. The remarkable effect that the ceramic structural member can be manufactured is brought about.

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】 α型窒化珪素粉末とβ型炭化珪素粉末を
主体とする混合粉末を１次焼結した後、１次焼結温度よ
りも高温でかつ１次焼結窒素分圧よりも高窒素分圧で２
次焼結を行なってセラミックス複合材料を製造するに際
し、α型窒化珪素粉末とβ型炭化珪素粉末の不純物酸素
量の和を１．０〜１．５重量％の範囲にすると共に不純
物炭素量の和を０．２５〜０．４０重量％の範囲とし、
マトリックス窒化珪素の長径方向の長さを１１．０μｍ
以下としたことを特徴とするセラミックス複合材料の製
造方法。1. After primary sintering of a mixed powder mainly composed of α-type silicon nitride powder and β-type silicon carbide powder, the temperature is higher than the primary sintering temperature and higher than the primary sintering nitrogen partial pressure. 2 with partial pressure of nitrogen
When manufacturing the ceramic composite material by performing the subsequent sintering, the sum of the impurity oxygen amounts of the α-type silicon nitride powder and the β-type silicon carbide powder is set to the range of 1.0 to 1.5% by weight, and The sum is in the range of 0.25 to 0.40% by weight,
The length of the matrix silicon nitride in the major axis direction is 11.0 μm.
A method for producing a ceramics composite material, comprising: