JP2539961B2 - Silicon nitride based sintered body and method for producing the same - Google Patents
Silicon nitride based sintered body and method for producing the sameInfo
- Publication number
- JP2539961B2 JP2539961B2 JP3117315A JP11731591A JP2539961B2 JP 2539961 B2 JP2539961 B2 JP 2539961B2 JP 3117315 A JP3117315 A JP 3117315A JP 11731591 A JP11731591 A JP 11731591A JP 2539961 B2 JP2539961 B2 JP 2539961B2
- Authority
- JP
- Japan
- Prior art keywords
- sintered body
- ratio
- auxiliary agent
- sialon
- silicon nitride
- 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】[0001]
【産業上の利用分野】本発明はとくに常温において優れ
た機械的強度を有し、生産性、コスト面において優れた
窒化ケイ素系焼結体およびその製造法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon nitride-based sintered body having excellent mechanical strength at room temperature and excellent in productivity and cost, and a method for producing the same.
【０００２】[0002]
【従来の技術】従来、窒化ケイ素系材料の強度向上を目
的として、焼結方法、焼結助剤、含有結晶相の限定など
様々な研究開発が行われてきた。たとえば、焼結法に関
しては、ホットプレス焼結法では、Ａｍ．Ｃｅｒａｍ．
Ｓｏｃ．Ｂｕｌｌ．，５２（１９７３）ｐｐ５６０で〜
１００ｋｇ／ｍｍ2（曲げ強度）が実現されており、ま
たガラスカプセルによる熱間静水圧プレス法（ＨＩＰ
法）等も開発されている。こうした手法では焼結体の強
度特性の面では優れた特性が得られているものの、生産
性、コストの面で優れた手法とは言えない。一方、こう
した問題に対して、ガス圧焼結法（例えば、三友、粉体
と工業、１２巻、１２号、ｐｐ２７、１９８９）がある
が、本方法では最終の焼結体の緻密化をβ−Ｓｉ3Ｎ4結
晶の粒成長に伴なうため、粗大結晶粒の析出による強度
劣化をまねく可能性が高いことに加え、一般には、１０
気圧以上のＮ2ガス圧をかけ焼結を実施するため、ホッ
トプレス法やＨＩＰ法と同様に焼結設備が大型となり、
特性面、生産面で十分優れた手法とは言えない。他方、
焼結助剤に関しては、主たる助剤としてＹ2Ｏ3を用いた
Ｓｉ3Ｎ4−Ａｌ2Ｏ3−Ｙ2Ｏ3系の窒化ケイ素系焼結体が
特公昭４９−２１０９１号、特公昭４８−３８４４８号
に開示されている。これらは、該特許明細書中に示され
ているように、β−Ｓｉ3Ｎ4結晶粒が焼結体中で繊維状
組織を形成し、これがマトリックス中に分散することか
ら強度、靭性を向上しうるものと考えられている。すな
わちこれは、β−Ｓｉ3Ｎ4結晶形が六方晶でありＣ軸方
向に結晶が異方性成長をすることを積極的に利用したも
のであり、とくに特公昭４８−３８４４８号や窯業協会
誌、９４巻、ｐｐ９６、１９８６に示されるように、繊
維状のβ−Ｓｉ3Ｎ4結晶粒がＣ軸方向に１０数μｍ以上
に成長している場合がある。しかしながら、本技術にお
いては、やはりこの粒成長が異常成長や気孔の発生をま
ねき、強度劣化をまねく可能性があり、また本方法での
焼結助剤だけを用いた焼結体では、焼結温度を１７００
〜１９００℃に上昇させなければ、緻密化が十分図れ
ず、大気圧付近のＮ2ガス圧焼結では、窒化ケイ素の昇
華分解が生じ、安定した焼結体を得られない場合があ
る。このため同じく、焼結体特性と生産性両面で十分優
れているとは言えない。一方、以上で述べてきた手法で
は、いずれも得られる焼結体の強度が、例えばＪＩＳ−
Ｒ１６０１に準拠した３点曲げ強度でせいぜい１００ｋ
ｇ／ｍｍ2前後であり、様々な窒化ケイ素系材料の応用
を考えた場合、必ずしも十分な特性が得られていない。2. Description of the Related Art Conventionally, various researches and developments have been carried out for the purpose of improving the strength of silicon nitride-based materials, such as sintering methods, sintering aids, and limiting the contained crystal phases. For example, regarding the sintering method, in the hot press sintering method, Am. Ceram.
Soc. Bull. , 52 (1973) pp560
100 kg / mm 2 (flexural strength) has been achieved, and the hot isostatic pressing method (HIP
Law) has also been developed. Although such a technique provides excellent strength characteristics of the sintered body, it cannot be said to be an excellent technique in terms of productivity and cost. On the other hand, there is a gas pressure sintering method (for example, Sanyu, Powder and Kogyo, Vol. 12, No. 12, pp27, 1989) for such a problem. However, in this method, the final densification of the sintered body is β Since it is accompanied by the grain growth of the —Si 3 N 4 crystal, there is a high possibility of causing strength deterioration due to the precipitation of coarse crystal grains.
Since N 2 gas pressure above atmospheric pressure is applied to carry out sintering, the size of the sintering equipment becomes large as in the hot press method and HIP method.
It cannot be said that this method is excellent in characteristics and production. On the other hand,
For the sintering aid, Si 3 N 4 -Al 2 O 3 -Y 2 O 3 system of silicon nitride sintered body is Japanese Patent Publication No. 49-21091 using Y 2 O 3 as a main aid, JP-B No. 48-38448. These, as shown in the patent specification, improve the strength and toughness because β-Si 3 N 4 crystal grains form a fibrous structure in a sintered body and this is dispersed in a matrix. It is considered possible. In other words, this is an active use of the fact that the β-Si 3 N 4 crystal form is hexagonal and the crystal grows anisotropically in the C-axis direction. Journal, Vol. 94, pp. 96, 1986, fibrous β-Si 3 N 4 crystal grains may grow to more than 10 μm or more in the C-axis direction. However, in the present technology, the grain growth also leads to abnormal growth and generation of pores, which may lead to deterioration in strength.In the case of a sintered body using only the sintering aid in the present method, sintering is not possible. Temperature 1700
Unless the temperature is increased to about 1900 ° C., densification cannot be sufficiently achieved, and in N 2 gas pressure sintering near atmospheric pressure, sublimation decomposition of silicon nitride occurs and a stable sintered body may not be obtained. For this reason, similarly, it cannot be said that both the properties of the sintered body and the productivity are sufficiently excellent. On the other hand, in the methods described above, the strength of the obtained sintered body is, for example, JIS-
Three-point bending strength based on R1601 and at most 100k
g / mm 2 , which means that sufficient characteristics are not necessarily obtained when various silicon nitride-based materials are applied.
【０００３】[0003]
【発明が解決しようとする課題】こうした従来技術にお
ける生産性と焼結体の機械的特性の両立を満足させる手
法を提供するのが本発明の課題である。SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of satisfying both the productivity and the mechanical properties of a sintered body in the prior art.
【０００４】[0004]
【課題を解決するための手段】本発明は、Ｓｉ3Ｎ4−第
１助剤−第２助剤の３元組成図において、第１助剤がＹ
2Ｏ3及びＭｇＯの２種よりなる組合せからなり、一方第
２助剤がＡｌ 2 Ｏ 3 よりなり、その組成の範囲が図１に示
される範囲、すなわちＳｉ3Ｎ4と第１助剤の添加組成比
がモル％で８５：１５から９９：１の範囲であり、かつ
Ｓｉ3Ｎ4と第２助剤の添加組成比がモル％で９０：１０
から９９：１の範囲で示される図１中の点Ａ、Ｂ、Ｃ、
Ｄで囲まれる範囲にあり、得られた焼結体中の結晶相に
α−Ｓｉ3Ｎ4とβ´−サイアロンの双方を含み、かつそ
の析出比がＸ線回折のピーク強度比で１：９９から３
０：７０の範囲内にあり、その焼結体の相対密度が９８
％以上であることを特徴とする窒化ケイ素系焼結体であ
る。According to the present invention, there is provided a ternary composition diagram of Si 3 N 4 -first auxiliary agent-second auxiliary agent, wherein the first auxiliary agent is Y
2 O 3 and MgO, and the second auxiliary agent is Al 2 O 3 , and its composition range is shown in FIG. 1, that is, Si 3 N 4 and the first auxiliary agent. The additive composition ratio is 85:15 to 99: 1 in mol%, and the additive composition ratio of Si 3 N 4 and the second auxiliary agent is 90:10 in mol%.
1 to 99: 1 shown in the range from 1 to 99: 1 in FIG.
In the range surrounded by the D, it includes both the crystal phases of the sintered body obtained α-Si 3 N 4 and β'- sialon, Katsuso
The precipitation ratio of X-ray diffraction peak intensity ratio is 1:99 to 3
Within the range of 0:70, the relative density of the sintered body is 98.
%, And is a silicon nitride-based sintered body.
【０００５】本発明では、かかる焼結体が、ＪＩＳＲ−
１６０１に準拠した３点曲げ強度が容易に１００ｋｇ／
ｍｍ2以上の特性を有する知見を得たものである。In the present invention, such a sintered body is a JISR-
The three-point bending strength according to 1601 is easily 100 kg /
The knowledge obtained has characteristics of mm 2 or more.
【０００６】又、本発明はα率９３％以上、平均粒径が
０．５μｍ以下の窒化ケイ素原料粉末を用い、これに図
１に示される組成範囲となる助剤であって、第１助剤が
Ｙ 2 Ｏ 3 及びＭｇＯの２種よりなる組合わせからなり、第
２助剤がＡｌ 2 Ｏ 3 及びＡｌＮの１種又は２種より選ばれ
た組合わせよりなる助剤を混合してなる混合粉末より圧
粉体を形成し、これを１３００〜１７００℃、Ｎ2ガス
を含む雰囲気中で焼結体相対密度が９６％以上、α−Ｓ
ｉ3Ｎ4とβ’−サイアロンの結晶層の析出比がＸ線回折
のピーク強度比で９９：１から５０：５０になるよう１
次焼結をおこなった後、Ｎ2ガスを含む雰囲気中で１３
００〜１７００℃で焼結体の相対密度が９８％以上にな
るよう２次焼結をおこなうことを特徴とする窒化ケイ素
系焼結体の製造法である。この製造法は、生産性にも十
分優れた焼結体を得る手法であると同時に、その焼結温
度が低いため異常粒成長に伴う焼結体の特性劣化を生じ
ることもない。本発明の焼結体が優れた強度特性を得る
効果は、微粒で等軸晶のα−Ｓｉ3Ｎ4と柱状化したβ´
−サイアロンの両方の結晶相を複合させることにより、
従来の柱状化したβ´−サイアロン（β−Ｓｉ3Ｎ4を含
む）結晶相のみで構成された焼結体に比較し、ヤング
率、硬度が向上する。これは材料の変形抵抗を示す物性
値でありセラミック材料のような脆性材料では、この値
を向上させることが広義では材料の強度向上につながる
ためである。さらに脆性材料の破壊の基本概念であるＧ
ｒｉｆｆｉｔｈの理論に従えば、焼結体の破壊強度σｆ
は次式で与えられる。Further, the present invention uses a silicon nitride raw material powder having an α ratio of 93% or more and an average particle size of 0.5 μm or less, which is an auxiliary agent having a composition range shown in FIG. Agent
It consists of a combination of Y 2 O 3 and MgO.
2 auxiliaries selected from one or two of Al 2 O 3 and AlN
A green compact is formed from a mixed powder obtained by mixing the auxiliaries consisting of the above combinations, and the green compact is formed at 1300 to 1700 ° C. in an atmosphere containing N 2 gas with a relative density of 96% or more, α-S
The precipitation ratio of the crystal layers of i 3 N 4 and β'-sialon should be adjusted to 99: 1 to 50:50 in terms of the peak intensity ratio of X-ray diffraction.
After the subsequent sintering, 13 in an atmosphere containing N 2 gas.
It is a method for producing a silicon nitride-based sintered body, which comprises performing secondary sintering so that the relative density of the sintered body becomes 98 % or more at 00 to 1700 ° C. This manufacturing method is a method for obtaining a sintered body having excellent productivity, and at the same time, because the sintering temperature is low, the characteristics of the sintered body do not deteriorate due to abnormal grain growth. The effect of the sintered body of the present invention to obtain excellent strength characteristics is that β ′ which is columnar with equiaxed α-Si 3 N 4 in the form of fine particles.
-By combining both crystalline phases of Sialon,
The Young's modulus and hardness are improved as compared with the conventional sintered body composed only of the columnar β′-sialon (including β-Si 3 N 4 ) crystal phase. This is a physical property value indicating the deformation resistance of the material, and in a brittle material such as a ceramic material, improving this value leads to an improvement in the strength of the material in a broad sense. G, which is the basic concept of fracture of brittle materials
According to the riffith theory, the fracture strength σf of the sintered body
Is given by
【０００７】σｆ＝Ｅ・γｓ／４ａ、 Ｅ；ヤング率、γｓ；破壊の表面エネルギ―、ａ；先在
亀裂長さ ここでγｓは粒界相の組成と厚みに依存すると考えられ
るため、とくに厚みの点で結晶粒の存在密度を向上させ
る結晶相の複合化は有利である。また本式に従えば、破
壊強度を向上させるためにはＥの増大とａの減少が重要
である。ａの値は工程上不可避な欠陥寸法を排除すれ
ば、結晶粒径に依存するため、微細結晶粒で充填性を向
上させた本発明はＥ、γｓの点で強度向上に有効であ
る。こうしたα型Ｓｉ3Ｎ4（α’−サイアロンを含む）
と柱状化したβ型Ｓｉ3Ｎ4（β’−サイアロンを含む）
の両方の結晶相を複合させる考え方は、例えば特開昭６
１−９１０６５号や特開平２−４４０６６号に開示され
ているが、いずれも組成的にはＳｉ3Ｎ4−ＡｌＮ−ＭＯ
（Ｍ；ＭｇＯ、Ｙ2Ｏ3、ＣａＯ等）の３成分系が主であ
り、その範囲もＡｌＮとＭＯの添加比がモル％で１：９
の限定された範囲で、α’−サイアロンとβ型のＳｉ3
Ｎ4（β’−サイアロンを含む）の複合した結晶相を生
成させることにより強度等の機械的特性の向上を示した
ものであり、またその実施例でも明らかなように各焼結
体の強度特性が曲げ強度で１００ｋｇ／ｍｍ2を安定し
て越える焼結体製法はいずれもホットプレス法によるも
のであり、工業的に安定して高い強度特性を得るまでに
至っていない。また、これらの焼結体はα’−サイアロ
ンとβ−Ｓｉ3Ｎ4（β’−サイアロンを含む）の間の熱
膨張係数の差が大きく、これが原因となり焼結体中に引
張の残留応力を発生させ、強度劣化を招く可能性があ
る。本発明はこうした条件の限定がなく工業的に安定し
て高強度な焼結体を提供することにある。Σf = E · γs / 4a, E: Young's modulus, γs: Surface energy of fracture, a: Preexisting crack length Here, γs is considered to depend on the composition and thickness of the grain boundary phase. It is advantageous to combine crystal phases to increase the density of crystal grains in terms of thickness. Further, according to this formula, it is important to increase E and decrease a in order to improve the fracture strength. Since the value of a depends on the crystal grain size if the defect size inevitable in the process is excluded, the present invention in which the filling property is improved by fine crystal grains is effective for improving the strength in terms of E and γs. Such α-type Si 3 N 4 (including α'-sialon)
Columnar β-type Si 3 N 4 (including β'-sialon)
The idea of compounding both crystal phases in JP
1-91065 and JP-A-2-44066, both of which are compositionally Si 3 N 4 -AlN-MO.
(M; MgO, Y 2 O 3, CaO etc.) are the major 3-component, addition ratio of its scope AlN and MO are in mole percent 1: 9
Within a limited range of α′-sialon and β-type Si 3
This shows that the mechanical properties such as strength were improved by generating a composite crystal phase of N 4 (including β′-sialon), and the strength of each sintered body was clearly shown in the examples. All of the methods for producing a sintered body having a bending strength that stably exceeds 100 kg / mm 2 are based on the hot pressing method, and have not been industrially stabilized to obtain high strength characteristics. In addition, these sintered bodies have a large difference in thermal expansion coefficient between α'-sialon and β-Si 3 N 4 (including β'-sialon), which causes tensile residual stress in the sintered body. May occur, resulting in deterioration of strength. An object of the present invention is to provide a high-strength sintered body that is industrially stable without being limited to such conditions.
【０００８】本発明の詳細な作用の説明をすると、組成
の範囲が図１に示される範囲、すなわちＳｉ3Ｎ4と第１
助剤の添加組成比がモル％で８５：１５から９９：１の
範囲であり、かつＳｉ3Ｎ4と第２助剤の添加組成比がモ
ル％で９０：１０から９９：１の範囲で示される図１中
の点Ａ、Ｂ、Ｃ、Ｄで囲まれる範囲とする。To explain the detailed operation of the present invention, the composition range is as shown in FIG. 1, that is, Si 3 N 4 and the first
When the additive composition ratio of the auxiliary agent is in the range of 85:15 to 99: 1 in mol%, and the additive composition ratio of the Si 3 N 4 and the second auxiliary agent is in the range of 90:10 to 99: 1 in the case of mol%. It is assumed that the area is surrounded by points A, B, C, and D shown in FIG.
【０００９】本組成範囲の限定はα−Ｓｉ3Ｎ4及び
β’−サイアロン結晶相の析出比率を本発明の範囲に限
定するためＳｉ3Ｎ4と第１助剤の添加組成比を限定し、
β’−サイアロンのＡｌ、Ｏの固溶量すなわちＺ値を
本発明の範囲に限定するためＳｉ3Ｎ4と第２助剤の添加
組成比を限定するものである。その詳細を以下に示す
と、Ｓｉ3Ｎ4と第１助剤の添加組成比がモル％で８５：
１５より第１助剤側へずれるとα−Ｓｉ3Ｎ4の含有量が
高く、焼結体強度の劣化をまねく原因になるとともに、
焼結中の雰囲気の影響を受け、焼結体表面に強度等の特
性を劣化させる表面層を生成するためである。また同組
成比が９９：１よりＳｉ3Ｎ4側へずれると焼結性が低下
しホットプレス法等の加圧焼結法を用いなければ十分緻
密な焼結体を得ることができないためである。一方Ｓｉ
3Ｎ4と第２助剤の添加組成比がモル％で９０：１０を越
えて第２助剤側へずれるとβ´−サイアロンの粗大結晶
が選択的に生成するため強度劣化をまねくとともに、や
はり焼結中の雰囲気の影響を受け、焼結体表面に強度等
の特性を劣化させる表面層を生成するためである。また
同組成比が９９：１よりＳｉ3Ｎ4側へずれると焼結性が
低下しホットプレス法等の加圧焼結法を用いなければ、
十分緻密な焼結体を得ることができないためである。さ
らに本発明の効果を顕著にするためには、焼結体中のα
−Ｓｉ3Ｎ4とβ´−サイアロンの結晶相の析出比がＸ線
回析のピ―ク強度比で、１次焼結体で９９：１から５
０：５０の範囲に析出させ、２次焼結体で１：９９から
３０：７０の範囲に析出させることが好ましい。この析
出比が１次焼結体で５０：５０を越えて高β−Ｓｉ3Ｎ4
側へずれると、２次焼結体ではβ’−サイアロンの粗大
粒成長を導き１：９９を越えて高α−Ｓｉ3Ｎ4側へずれ
ると緻密質の２次焼結体が得られないためである。２次
焼結体の析出比が、１：９９を越えて低α−Ｓｉ3Ｎ4側
へずれると結晶相の複合化の効果が十分現われず強度向
上の効果が十分ではない。また析出比が３０：７０を越
えて高α−Ｓｉ3Ｎ4側へずれるとβ’−サイアロン柱状
晶組織の効果が減少しやはり結晶相の複合化の効果が十
分現れず強度向上の効果が十分ではない。また、この組
成範囲で焼結体中のβ’−サイアロン（一般式Ｓｉ6-Z
ＡｌZＯZＮ8-Z）のＺ値を０＜Ｚ＜１．０の範囲にして
粒界相を制御すると高強度が安定する。In order to limit the precipitation ratio of the α-Si 3 N 4 and β'-sialon crystal phases to the range of the present invention, the composition range is limited so that the composition ratio of Si 3 N 4 and the first auxiliary agent is limited. ,
The composition ratio of Si 3 N 4 and the second auxiliary agent is limited in order to limit the solid solution amount of Al and O of β′-sialon, that is, the Z value, to the range of the present invention. The details are shown below. The additive composition ratio of Si 3 N 4 and the first auxiliary is 85% in mol%.
If it shifts from 15 to the first auxiliary agent side, the content of α-Si 3 N 4 is high, which causes deterioration of the strength of the sintered body, and
This is because a surface layer is formed on the surface of the sintered body which is affected by the atmosphere during sintering and deteriorates properties such as strength. Further, if the composition ratio deviates from 99: 1 to the Si 3 N 4 side, the sinterability deteriorates and a sufficiently dense sintered body cannot be obtained unless a pressure sintering method such as a hot pressing method is used. is there. On the other hand, Si
When the additive composition ratio of 3 N 4 and the second auxiliary exceeds 90:10 in mol% and shifts to the second auxiliary side, coarse crystals of β′-sialon are selectively formed, leading to deterioration of strength and This is also because the surface layer that deteriorates properties such as strength is formed on the surface of the sintered body under the influence of the atmosphere during sintering. Further, if the composition ratio deviates from 99: 1 to the Si 3 N 4 side, the sinterability deteriorates, and unless a pressure sintering method such as a hot pressing method is used.
This is because it is not possible to obtain a sufficiently dense sintered body. In order to make the effect of the present invention more remarkable, α in the sintered body
-Si 3 N 4 and β'- precipitation ratio of crystalline phases of sialon peak of X-ray diffraction - using the clock intensity ratio, 99 in the primary sintered body: 1 to 5
It is preferable to deposit in the range of 0:50 and to deposit in the range of 1:99 to 30:70 in the secondary sintered body. This precipitation ratio exceeds 50:50 in the primary sintered body and is high in β-Si 3 N 4
If it shifts to the side, the secondary sintered body leads to coarse grain growth of β'-sialon, and if it shifts to the high α-Si 3 N 4 side beyond 1:99, a dense secondary sintered body cannot be obtained. This is because. If the precipitation ratio of the secondary sintered body exceeds 1:99 and shifts to the low α-Si 3 N 4 side, the effect of compounding the crystal phase is not sufficiently exhibited and the effect of improving the strength is not sufficient. Further, when the precipitation ratio exceeds 30:70 and shifts to the high α-Si 3 N 4 side, the effect of the β'-sialon columnar crystal structure decreases, and the composite effect of the crystal phase does not sufficiently appear and the effect of improving the strength is obtained. Not enough. Further, in this composition range, β'-sialon (general formula Si 6-Z
When the grain boundary phase is controlled by setting the Z value of Al Z O Z N 8-Z in the range of 0 <Z <1.0, high strength is stabilized.
【００１０】また本発明はその焼結体の製法条件も重要
である。すなわちα率９３％以上、平均粒径が０．７μ
ｍ以下の窒化ケイ素原料粉末を用い、図１に示される組
成範囲の助剤となる混合粉末よりなる圧粉体を１３００
〜１７００℃、Ｎ2ガスを含む雰囲気中で焼結体相対密
度が９６％以上、α−Ｓｉ3Ｎ4とβ’−サイアロンの結
晶相の析出比がＸ線回折のピーク強度比で、１：９９か
ら５０：５０になるよう１次焼結をおこなった後、Ｎ2
ガスを含む雰囲気中、１３００〜１７００℃で焼結体相
対密度が９９％以上になるよう２次焼結をおこなうこと
が好ましい。ここで窒化ケイ素原料としてα率９３％以
上、平均粒径が０．７μｍ以下の窒化ケイ素原料粉末を
必要とする理由は低温域での焼結性を向上させるためで
ある。また本発明の組成の範囲を選択することにより、
焼結条件は１次焼結が１３００〜１７００℃のＮ2ガス
を含む雰囲気中の低温域で可能となった。このため結晶
粒の複合化がより微細な結晶粒により構成され、その効
果を顕著にするとともに、１次焼結がプッシャー式ある
いはベルト式等の開放型連続焼結炉により、同時に生産
性の優れた焼結が可能となる。この詳細な説明を加える
と、一般に強度特性に優れた窒化ケイ素系材料の焼結法
としては、いわゆるバッチ式焼結炉によるガス圧焼結が
主であるが、この方式では炉内の温度分布のばらつきや
ロット間の条件ばらつき等が必ず生じるために、量産部
品等の用途のセラミック材料を安定して供給する製法と
しては十分とは言えない。また窒化ケイ素は大気圧のＮ
2雰囲気下では１７００℃以上の温度域で昇華分解する
ため、加圧Ｎ2雰囲気下で焼結する必要があり、設備面
でバッチ式焼結炉を用いていた。この点からも本発明は
その生産性を同時に向上させた点で工業的に重要であ
る。ここで焼結温度を１３００〜１７００℃としたの
は、上述した理由の他に１３００℃未満では焼結体の緻
密化が十分図れず、１７００℃を超えると上述したα−
Ｓｉ3Ｎ4とβ’−サイアロンの析出相の比率がＸ線回折
のピーク強度比で１：９９〜３０：７０の範囲に入らな
いことに加え、結晶粒の粗大化が顕著になり強度特性の
劣化やばらつきの原因となる。また１次焼結体の相対密
度を９６％以上に焼結するのは、２次焼結において焼結
体の緻密化を十分達成するためである。一方２次焼結条
件の焼結温度を１３００〜１７００℃としたのは、やは
り１３００℃未満では焼結体の緻密化が十分図れず、１
７００℃を超えると上述したα−Ｓｉ3Ｎ4とβ’−サイ
アロンの析出相の比率がＸ線回折のピーク強度比で１：
９９〜３０：７０の範囲に入らないことに加え、焼結粒
の粗大化が顕著になり強度特性の劣化やばらつきの原因
となるためである。とくに２次焼結温度に関しては、１
次焼結温度以下が前述の点で好ましい。一方得られた焼
結体の相対密度が９８％未満であると、強度特性にばら
つきが生じるため好ましくない。また上述した条件の組
成、焼結法と、α率９３％以上、平均粒径０．５μｍの
窒化ケイ素原料とを組合せることにより、α−Ｓｉ3Ｎ4
結晶粒の平均粒径が０．５μｍ以下及び、β’−サイア
ロン結晶粒の平均粒径が５μｍ以下である複合結晶相が
容易に得られる。In the present invention, the manufacturing conditions of the sintered body are also important. That is, the α ratio is 93% or more and the average particle size is 0.7 μm.
Using a silicon nitride raw material powder having a particle size of m or less, a green compact 1300 made of a mixed powder as an auxiliary agent having a composition range shown in FIG.
˜1700 ° C., relative density of the sintered body is 96% or more in an atmosphere containing N 2 gas, and the precipitation ratio of the crystal phases of α-Si 3 N 4 and β′-sialon is 1 in terms of peak intensity ratio of X-ray diffraction. : 99 to 50:50 and then N 2
It is preferable to perform secondary sintering at 1300 to 1700 ° C. in an atmosphere containing gas so that the relative density of the sintered body becomes 99% or more. Here, the reason that the silicon nitride raw material powder is required to have an α ratio of 93% or more and an average particle size of 0.7 μm or less is to improve the sinterability in a low temperature range. Further, by selecting the composition range of the present invention,
As for the sintering conditions, the primary sintering became possible in a low temperature range in an atmosphere containing N 2 gas at 1300 to 1700 ° C. For this reason, the compounding of crystal grains is made up of finer crystal grains, which makes the effect remarkable, and at the same time, the primary sintering is performed by an open type continuous sintering furnace such as a pusher type or a belt type, which is excellent in productivity at the same time. Sintering becomes possible. In addition to this detailed description, gas pressure sintering using a so-called batch type sintering furnace is mainly used as a method for sintering silicon nitride-based materials generally having excellent strength characteristics. Therefore, it is not sufficient as a manufacturing method for stably supplying ceramic materials for use in mass-produced parts and the like because variations in conditions and variations in conditions between lots always occur. Also, silicon nitride is N at atmospheric pressure.
Since it decomposes by sublimation in a temperature range of 1700 ° C. or higher under 2 atmospheres, it is necessary to sinter under a pressurized N 2 atmosphere, and a batch-type sintering furnace was used in terms of equipment. From this point as well, the present invention is industrially important in that its productivity is improved at the same time. The reason why the sintering temperature is set to 1300 to 1700 ° C. is that, for reasons other than the above, if the temperature is less than 1300 ° C., the sintered body cannot be sufficiently densified, and if it exceeds 1700 ° C.
The ratio of the precipitation phases of Si 3 N 4 and β'-sialon does not fall within the range of 1:99 to 30:70 in the peak intensity ratio of X-ray diffraction, and the coarsening of crystal grains becomes remarkable, and the strength characteristics Cause deterioration and variation. The reason why the relative density of the primary sintered body is sintered to 96% or more is to sufficiently achieve the densification of the sintered body in the secondary sintering. On the other hand, the reason why the sintering temperature of the secondary sintering condition is set to 1300 to 1700 ° C. is that if the temperature is lower than 1300 ° C., the sintered body cannot be sufficiently densified.
When the temperature exceeds 700 ° C., the ratio of the α-Si 3 N 4 and β′-sialon precipitate phases is 1: in the X-ray diffraction peak intensity ratio.
This is because in addition to not falling within the range of 99 to 30:70, coarsening of the sintered grains becomes remarkable, which causes deterioration and variation in strength characteristics. Especially regarding the secondary sintering temperature, 1
The temperature below the next sintering temperature is preferable from the above point. On the other hand, if the relative density of the obtained sintered body is less than 98%, the strength characteristics vary, which is not preferable. Further, by combining the composition and sintering method under the above-mentioned conditions with a silicon nitride raw material having an α ratio of 93% or more and an average particle size of 0.5 μm, α-Si 3 N 4 can be obtained.
A composite crystal phase in which the average grain size of crystal grains is 0.5 μm or less and the average grain size of β′-sialon crystal grains is 5 μm or less can be easily obtained.
【００１１】その結果、その曲げ強度が１００ｋｇ／ｍ
ｍ2を容易に越え、そのばらつきもきわめて少なくな
る。以上により本発明の焼結体が強度特性、生産性、コ
ストに優れたものであることが明らかとなった。As a result, the bending strength is 100 kg / m.
It easily exceeds m 2 and the variation is extremely small. From the above, it became clear that the sintered body of the present invention is excellent in strength characteristics, productivity and cost.
【００１２】[0012]
実施例１ 平均粒径０．４μｍ、α結晶化率９６％、酸素量１．４
重量％の窒化ケイ素原料粉末および、平均粒径０．８μ
ｍ、０．４μｍ、０．５μｍのＹ2Ｏ3、Ａｌ2Ｏ3、Ａｌ
Ｎ、ＭｇＯの各粉末を表１に示す組成で、エタノール
中、１００時間、ナイロン製ボールミルにて湿式混合し
たのち、乾燥して得られた混合粉末を３０００ｋｇ／ｃ
ｍ2でＣＩＰ成形し、この成形体をＮ2ガス１気圧中で１
５００℃で６時間、１６５０℃で３時間１次焼結した。
得られた焼結体を１６００℃、１０００気圧Ｎ2ガス雰
囲気中で１時間、２次焼結した。この焼結体よりＪＩＳ
Ｒ１６０１に準拠した３ｍｍ×４ｍｍ×４０ｍｍ相当の
抗折試験片を切り出し、＃８００ダイヤモンド砥石によ
り切削加工仕上げした後、引張面については＃３０００
のダイヤモンドペーストによりラッピング仕上げ加工し
た後、ＪＩＳＲ１６０１に準拠して３点曲げ強度を１５
本ずつ実施した。表２中には１次焼結体の相対密度、２
次焼結体の相対密度、結晶相の比率と曲げ強度及びワイ
ブル係数を示した。なお、結晶相の比率に関してはＸ線
回折法により求めた各結晶相のピーク高さ比より算出し
た。Example 1 Average particle size 0.4 μm, α crystallization ratio 96%, oxygen content 1.4
% Silicon nitride raw material powder and average particle size 0.8 μ
m, 0.4 μm, 0.5 μm Y 2 O 3 , Al 2 O 3 , Al
Each powder of N and MgO having the composition shown in Table 1 was wet-mixed in ethanol for 100 hours with a nylon ball mill, and then dried to obtain a mixed powder of 3000 kg / c.
and CIP molding at m 2, 1 the molded body in a N 2 gas 1 atm
Primary sintering was performed at 500 ° C. for 6 hours and 1650 ° C. for 3 hours.
The obtained sintered body was subjected to secondary sintering for 1 hour at 1600 ° C. and 1000 atmospheric pressure N 2 gas atmosphere. JIS from this sintered body
A bending test piece corresponding to 3 mm x 4 mm x 40 mm in conformity with R1601 was cut out and cut and finished with a # 800 diamond grindstone.
After lapping with the diamond paste of No. 3, the three-point bending strength is set to 15 according to JIS R1601.
Book by book. In Table 2, the relative density of the primary sintered body, 2
The relative density, crystal phase ratio and bending strength, and Weibull coefficient of the next sintered body are shown. The crystal phase ratio was calculated from the peak height ratio of each crystal phase obtained by the X-ray diffraction method.
【００１３】[0013]
【表１】 [Table 1]
【００１４】[0014]
【表２】 実施例２ 市販の窒化ケイ素原料粉末（平均粒径＝０．７μｍ、α
結晶化率＝９３％、酸素量＝１．５重量％）に実施例１
と同様の助剤粉末を実施例１の組成１〜５になるよう、
実施例１と同様の手法で混合、乾燥し成形した。この成
形体をＮ2ガス１気圧中で１５５０℃で５時間、１６５
０℃で２時間１次焼結した後、１６００℃、１０００気
圧Ｎ2ガス雰囲気中で１時間、２次焼結した。この焼結
体より実施例１と同様の手法によりＪＩＳＲ１６０１に
準拠した抗折試験片を加工し、同様の評価に供試した。
この結果を表３に示す。[Table 2] Example 2 Commercially available silicon nitride raw material powder (average particle size = 0.7 μm, α
Crystallization rate = 93%, oxygen amount = 1.5% by weight)
The same auxiliary powder as in Example 1 was used to obtain compositions 1 to 5,
Mixing, drying and molding were carried out in the same manner as in Example 1. This molded body was heated at 1550 ° C. for 5 hours in 1 atmosphere of N 2 gas for 165
After primary sintering at 0 ° C. for 2 hours, secondary sintering was performed at 1600 ° C. in a 1000 atmosphere N 2 gas atmosphere for 1 hour. A bending test piece in accordance with JIS R1601 was processed from this sintered body by the same method as in Example 1 and subjected to the same evaluation.
The results are shown in Table 3.
【００１５】[0015]
【表３】 実施例３ 実施例１と同様の原料粉末を、実施例１で示した組成１
〜５について同様の手法で混合、乾燥、成形した。得ら
れた成形体をＮ2ガス１気圧中で１５００℃で６時間、
１６５０℃で３時間１次焼結した後、連続して１６００
℃、８０気圧Ｎ2ガス雰囲気中で２時間、２次焼結し
た。得られた焼結体より、実施例１と同様の手法でＪＩ
ＳＲ１６０１に準拠した抗折試験片を切り出し、実施例
１と同様の手法で評価した。この結果を表４に示す。[Table 3] Example 3 The same raw material powder as in Example 1 was used as the composition 1 shown in Example 1.
-5 were mixed, dried and molded in the same manner. The obtained molded body was treated with N 2 gas at 1 atm at 1500 ° C. for 6 hours,
After primary sintering at 1650 ° C for 3 hours, continuous 1600
Secondary sintering was performed in a N 2 gas atmosphere at 80 ° C. and 80 atm for 2 hours. From the obtained sintered body, a JI was prepared in the same manner as in Example 1.
A bending test piece conforming to SR1601 was cut out and evaluated in the same manner as in Example 1. Table 4 shows the results.
【００１６】[0016]
【表４】 [Table 4]
【００１７】[0017]
【発明の効果】本発明によれば、特に常温において優れ
た機械的強度を有する窒化ケイ素系焼結体を、生産性、
コスト面において有利に提供される。According to the present invention, a silicon nitride-based sintered body having excellent mechanical strength, particularly at room temperature, can be produced with high productivity,
Advantageously provided in terms of cost.
【図１】本発明における組成範囲を示す３元組成図であ
る。FIG. 1 is a ternary composition diagram showing a composition range in the present invention.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 山川 晃 兵庫県伊丹市昆陽北一丁目１番１号 住 友電気工業株式会社 伊丹製作所内 (72)発明者 三宅 雅也 兵庫県伊丹市昆陽北一丁目１番１号 住 友電気工業株式会社 伊丹製作所内 (56)参考文献 特開 平２−22173（ＪＰ，Ａ) 特開 平４−202060（ＪＰ，Ａ) 特開 平５−58739（ＪＰ，Ａ) ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Yamakawa 1-1-1 Kunyokita, Itami City, Hyogo Prefecture Sumitomo Electric Industries, Ltd. Itami Works (72) Inventor Masaya Miyake 1-chome, Koyo, Itami City, Hyogo Prefecture No. 1 No. 1 Sumitomo Electric Industries, Ltd. Itami Works (56) Reference JP-A-2-22173 (JP, A) JP-A-4-202060 (JP, A) JP-A-5-58739 (JP, A) )
Claims (4)
成図において、第１助剤がＹ2Ｏ3及びＭｇＯの２種より
なる組合わせからなり、一方第２助剤がＡｌ2Ｏ3 であ
り、その組成の範囲が図１に示される範囲、すなわちＳ
ｉ3Ｎ4と第１助剤の添加組成比がモル％で８５：１５か
ら９９：１の範囲であり、かつＳｉ3Ｎ4と第２助剤の添
加組成比がモル％で９０：１０から９９：１の範囲で示
される図１中の点Ａ、Ｂ、Ｃ、Ｄで囲まれる範囲にあ
り、得られた焼結体中の結晶相にα−Ｓｉ3Ｎ4とβ´−
サイアロンの双方を含み、かつその析出比がＸ線回折の
ピーク強度比で１：９９から３０：７０の範囲内にあ
り、その焼結体の相対密度が９８％以上であることを特
徴とする窒化ケイ素系焼結体。1. A ternary composition diagram of Si 3 N 4 -first auxiliary agent-second auxiliary agent, wherein the first auxiliary agent is a combination of two kinds of Y 2 O 3 and MgO, while the second auxiliary agent is the second auxiliary agent. aid Al 2 O 3 der
Ri, range range of the composition is shown in Figure 1, namely S
The additive composition ratio of i 3 N 4 and the first auxiliary is 85:15 to 99: 1 in mol%, and the additive composition ratio of Si 3 N 4 and the second auxiliary is 90:10 in mol%. 1 to 99: 1 in the range surrounded by points A, B, C and D in FIG. 1, and α-Si 3 N 4 and β′-in the crystal phase in the obtained sintered body.
It contains both sialon and its deposition ratio is determined by X-ray diffraction.
The peak intensity ratio is within the range of 1:99 to 30:70.
And a relative density of the sintered body is 98% or more.
径が０．５μｍ以下及び、β´−サイアロン結晶粒の平
均粒径が５μｍ以下であることを特徴とする請求項１記
載の窒化ケイ素系焼結体。2. The sintered body is characterized in that the average grain size of α-Si 3 N 4 crystal grains is 0.5 μm or less, and the average grain size of β′-sialon crystal grains is 5 μm or less. Item 1. A silicon nitride-based sintered body according to item 1.
ｉ6-ZＡｌZＯZＮ8-Z（式中０＜Ｚ＜１．０の範囲にある
であることを特徴とする請求項１又は２記載の窒化ケイ
素焼結体。3. The β'-sialon in the sintered body has the general formula S
i 6-Z Al Z O Z N 8-Z (wherein 0 <Z <1.0 in the formula, the silicon nitride sintered body according to claim 1 or 2, wherein
以下の窒化ケイ素原料粉末を用い、これに図１に示され
る組成範囲となる助剤であって、第１助剤がＹ 2 Ｏ 3 及び
ＭｇＯの２種よりなる組合わせからなり、第２助剤がＡ
ｌ 2 Ｏ 3 及びＡｌＮの１種又は２種より選ばれた組合わせ
よりなる助剤を混合してなる混合粉末より圧粉体を形成
し、これを１３００〜１７００℃、Ｎ2ガスを含む雰囲
気中で焼結体相対密度が９６％以上、α−Ｓｉ3Ｎ4と
β’−サイアロンの結晶層の析出比がＸ線回折のピーク
強度比で、９９：１から５０：５０になるよう１次焼結
をおこなった後、Ｎ2ガスを含む雰囲気中で１３００〜
１７００℃で焼結体の相対密度が９８％以上、α−Ｓｉ
3 Ｎ 4 とβ’−サイアロン結晶層の析出比がＸ線回折のピ
ーク強度比で１：９９から３０：７０になるよう２次焼
結をおこなうことを特徴とする窒化ケイ素系焼結体の製
造法。4. The α ratio is 93% or more, and the average particle size is 0.5 μm.
The following silicon nitride raw material powder was used, and an auxiliary agent having a composition range shown in FIG. 1 in which the first auxiliary agent was Y 2 O 3 and
It consists of a combination of two types of MgO, and the second auxiliary agent is A
A combination selected from one or two of l 2 O 3 and AlN.
A green compact is formed from a mixed powder obtained by mixing an auxiliary agent, and the green compact is formed at 1300 to 1700 ° C. in an atmosphere containing N 2 gas with a relative density of 96% or more and α-Si 3 N 4 After the primary sintering was performed so that the precipitation ratio of the crystal layer of β and β′-sialon was from 99: 1 to 50:50 in terms of peak intensity ratio of X-ray diffraction, 1300 to 1300 in an atmosphere containing N 2 gas.
The relative density of the sintered body is 98% or more at 1700 ° C., α-Si
The precipitation ratio of 3 N 4 and β'-sialon crystal layer was determined by X-ray diffraction.
A method for producing a silicon nitride-based sintered body, which comprises performing secondary sintering so that a peak strength ratio becomes 1:99 to 30:70 .
Priority Applications (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3117315A JP2539961B2 (en) | 1991-05-22 | 1991-05-22 | Silicon nitride based sintered body and method for producing the same |
| US07/825,989 US5204297A (en) | 1991-05-22 | 1992-01-27 | Silicon nitride sintered body and process for producing the same |
| CA002060241A CA2060241C (en) | 1991-05-22 | 1992-01-29 | Silicon nitride sintered body and process for producing the same |
| DE69201910T DE69201910T2 (en) | 1991-05-22 | 1992-01-30 | Silicon nitride sintered body and process for its production. |
| EP92101525A EP0514622B1 (en) | 1991-05-22 | 1992-01-30 | Silicon nitride sintered body and process for producing the same |
| US07/957,506 US5275772A (en) | 1991-05-22 | 1992-10-05 | Silicon nitride sintered body and process for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3117315A JP2539961B2 (en) | 1991-05-22 | 1991-05-22 | Silicon nitride based sintered body and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0570233A JPH0570233A (en) | 1993-03-23 |
| JP2539961B2 true JP2539961B2 (en) | 1996-10-02 |
Family
ID=14708711
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3117315A Expired - Lifetime JP2539961B2 (en) | 1991-05-22 | 1991-05-22 | Silicon nitride based sintered body and method for producing the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2539961B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7829491B2 (en) | 2004-11-26 | 2010-11-09 | Kyocera Corporation | Silicon nitride sintered body and manufacturing method thereof, member for molten metal, member for hot working, and member for digging |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0625039B2 (en) * | 1988-07-08 | 1994-04-06 | 日本タングステン株式会社 | Silicon nitride sintered body and method for manufacturing the same |
| JPH03131589A (en) * | 1989-10-17 | 1991-06-05 | Nippon Mining Co Ltd | Production of compound semiconductor single crystal |
-
1991
- 1991-05-22 JP JP3117315A patent/JP2539961B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7829491B2 (en) | 2004-11-26 | 2010-11-09 | Kyocera Corporation | Silicon nitride sintered body and manufacturing method thereof, member for molten metal, member for hot working, and member for digging |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0570233A (en) | 1993-03-23 |
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