JPH05148028A - Method for manufacturing silicon nitride sintered body - Google Patents
Method for manufacturing silicon nitride sintered bodyInfo
- Publication number
- JPH05148028A JPH05148028A JP3314534A JP31453491A JPH05148028A JP H05148028 A JPH05148028 A JP H05148028A JP 3314534 A JP3314534 A JP 3314534A JP 31453491 A JP31453491 A JP 31453491A JP H05148028 A JPH05148028 A JP H05148028A
- Authority
- JP
- Japan
- Prior art keywords
- sintered body
- silicon nitride
- ratio
- auxiliary agent
- sintering
- 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.)
- Pending
Links
- 229910052581 Si3N4 Inorganic materials 0.000 title claims abstract description 24
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 title claims abstract description 24
- 238000004519 manufacturing process Methods 0.000 title claims description 7
- 238000000034 method Methods 0.000 title description 37
- 238000005245 sintering Methods 0.000 claims abstract description 44
- 239000000203 mixture Substances 0.000 claims abstract description 26
- 239000012752 auxiliary agent Substances 0.000 claims abstract description 16
- 239000000843 powder Substances 0.000 claims abstract description 14
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims abstract description 10
- 239000002245 particle Substances 0.000 claims abstract description 8
- 239000011812 mixed powder Substances 0.000 claims abstract description 4
- 239000013078 crystal Substances 0.000 claims description 31
- 239000012298 atmosphere Substances 0.000 claims description 14
- 239000000654 additive Substances 0.000 claims description 5
- 230000000996 additive effect Effects 0.000 claims description 5
- 238000001556 precipitation Methods 0.000 claims description 4
- 238000002441 X-ray diffraction Methods 0.000 claims description 3
- 238000010586 diagram Methods 0.000 claims description 3
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 3
- 239000002994 raw material Substances 0.000 abstract description 11
- 230000000694 effects Effects 0.000 abstract description 10
- PCTMTFRHKVHKIS-BMFZQQSSSA-N (1s,3r,4e,6e,8e,10e,12e,14e,16e,18s,19r,20r,21s,25r,27r,30r,31r,33s,35r,37s,38r)-3-[(2r,3s,4s,5s,6r)-4-amino-3,5-dihydroxy-6-methyloxan-2-yl]oxy-19,25,27,30,31,33,35,37-octahydroxy-18,20,21-trimethyl-23-oxo-22,39-dioxabicyclo[33.3.1]nonatriaconta-4,6,8,10 Chemical compound C1C=C2C[C@@H](OS(O)(=O)=O)CC[C@]2(C)[C@@H]2[C@@H]1[C@@H]1CC[C@H]([C@H](C)CCCC(C)C)[C@@]1(C)CC2.O[C@H]1[C@@H](N)[C@H](O)[C@@H](C)O[C@H]1O[C@H]1/C=C/C=C/C=C/C=C/C=C/C=C/C=C/[C@H](C)[C@@H](O)[C@@H](C)[C@H](C)OC(=O)C[C@H](O)C[C@H](O)CC[C@@H](O)[C@H](O)C[C@H](O)C[C@](O)(C[C@H](O)[C@H]2C(O)=O)O[C@H]2C1 PCTMTFRHKVHKIS-BMFZQQSSSA-N 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 15
- 230000006866 deterioration Effects 0.000 description 8
- 238000005452 bending Methods 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 238000000280 densification Methods 0.000 description 5
- 238000013329 compounding Methods 0.000 description 4
- 238000000354 decomposition reaction Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 238000007731 hot pressing Methods 0.000 description 3
- 150000003949 imides Chemical class 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 229910010293 ceramic material Inorganic materials 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 229910003460 diamond Inorganic materials 0.000 description 2
- 239000010432 diamond Substances 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 238000013001 point bending Methods 0.000 description 2
- 238000000859 sublimation Methods 0.000 description 2
- 230000008022 sublimation Effects 0.000 description 2
- 239000002344 surface layer Substances 0.000 description 2
- 239000004677 Nylon Substances 0.000 description 1
- 244000309464 bull Species 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000001513 hot isostatic pressing Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000005121 nitriding Methods 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
Landscapes
- Ceramic Products (AREA)
Abstract
(57)【要約】
【目的】 本発明は特に常温において優れた機械的強度
を有し、生産性、コスト面において有利に窒化ケイ素系
焼結体を提供する。
【構成】 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用い、Ｓｉ3Ｎ4−第１助剤（Ｙ
2Ｏ3＋ＭｇＯ）−第２助剤（Ａｌ2Ｏ3、ＡｌＮの１種又
は２種）の組成範囲が図１のＡＢＣＤの範囲にある混合
粉末よりなる圧粉体もしくは成形体を１４００〜１６０
０℃、１．１気圧以下のＮ2ガス中で相対密度が９６％
以上９８．５％以下になるように１次焼結した後、１４
００〜１７００℃、１０気圧以上のＮ2ガス中で相対密
度が９９．５％以上になるように２次焼結することを特
徴とする。
【効果】 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容易に製造することができる。
(57) [Summary] [Object] The present invention provides a silicon nitride-based sintered body which has excellent mechanical strength particularly at room temperature and is advantageous in terms of productivity and cost. [Structure] A silicon nitride raw material powder having an α ratio of 93% or more and an average particle size of 0.7 μm or less is used, and Si 3 N 4 -first auxiliary agent (Y
2 O 3 + MgO) - the second aid (Al 2 O 3, 1 kind of AlN or two) green compact or compacts composition range consisting of mixed powder in the range of ABCD Figure 1 1400-160
96% relative density in N 2 gas at 0 ° C and 1.1 atm or less
After the primary sintering so as to be 98.5% or less, 14
It is characterized in that the secondary sintering is carried out so that the relative density becomes 99.5% or more in N 2 gas at 00 to 1700 ° C. and 10 atm or more. [Effect] At room temperature, a silicon nitride-based sintered body having excellent mechanical strength can be easily manufactured.
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の製造法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a silicon nitride-based sintered body which has excellent mechanical strength at room temperature and is excellent in productivity and cost.
【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 such as a sintering method, a sintering aid, and a limitation of contained crystal phases have been carried out for the purpose of improving the strength of silicon nitride materials. For example, regarding the sintering method, in the hot press sintering method, Am. Ceram.
Soc. Bull. , 52 (1973) pp560-
100 kg / mm 2 (bending strength) has been realized, and the hot isostatic pressing method (HIP
Law) is also being developed. Although such a method has obtained excellent characteristics in terms of strength characteristics of the sintered body, it cannot be said to be an excellent method 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, but in this method, the final densification of the sintered body is β since accompanying the grain growth of -Si 3 N 4 crystal, in addition to it is likely to lead to deterioration in strength due to coarse grain precipitation, in general, 10
Since sintering is performed by applying N 2 gas pressure of atmospheric pressure or more, the sintering equipment becomes large like the hot press method and the HIP method,
It cannot be said that it is a sufficiently excellent method in terms of 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. As shown in the patent specification, these improve the strength and toughness because β-Si 3 N 4 crystal grains form a fibrous structure in the sintered body and are dispersed in the matrix. It is considered possible. That is, this is a positive use of the fact that the β-Si 3 N 4 crystal form is a hexagonal crystal and the crystal anisotropically grows in the C-axis direction. In particular, Japanese Patent Publication No. 48-38448 and Ceramic Industry Association As shown in the magazine, Vol. 94, pp96, 1986, fibrous β-Si 3 N 4 crystal grains may grow to 10 and several μm or more in the C-axis direction. However, in the present technology, this grain growth may lead to abnormal growth and generation of pores, and may lead to strength deterioration, and in the sintered body using only the sintering aid in this method, Temperature 1700
Unless the temperature is raised to ˜1900 ° C., sufficient densification cannot be achieved, and in N 2 gas pressure sintering near atmospheric pressure, sublimation decomposition of silicon nitride may occur and a stable sintered body may not be obtained. Therefore, similarly, it cannot be said that the sintered body is sufficiently excellent in both characteristics and productivity. On the other hand, in the methods described above, the strength of the obtained sintered body is, for example, JIS-
3-point bending strength conforming to R1601 at most 100k
It is around g / mm 2 , and when considering the application of various silicon nitride materials, sufficient characteristics are not always obtained.
【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 the sintered body in the prior art.
【０００４】[0004]
【課題を解決するための手段】本発明は、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
用い、Ｓｉ3Ｎ4−第１助剤−第２助剤の３元組成図にお
いて、第１助剤がＹ2Ｏ3及びＭｇＯの２種よりなる組合
せからなり、一方第２助剤がＡｌ2Ｏ3及びＡｌＮの２種
より選ばれた組合せよりなり、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９５：５の範囲であり、か
つＳｉ3Ｎ4と第２助剤の添加組成比がモル％で９０：１
０から９８：２の範囲で示される図１中の点Ａ、Ｂ、
Ｃ、Ｄで囲まれる範囲の助剤とからなる混合粉末よりな
る圧粉体、もしくは成形体を１４００〜１６００℃、
１．１気圧以下のＮ2ガス雰囲気中で焼結体相対密度が
９６％以上９８．５％以下になるよう１次焼結をおこな
った後、１４００〜１７００℃、１０気圧以上のＮ2ガ
ス雰囲気中で焼結体相対密度が９９．５％以上になるよ
う２次焼結をおこない、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むことを特徴
とするため、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。According to the present invention, a silicon nitride raw material powder having an α ratio of 93% or more and an average particle size of 0.7 μm or less is used, and Si 3 N 4 -first auxiliary agent-second auxiliary agent is used. In the ternary composition diagram, the first auxiliary consists of a combination of two kinds of Y 2 O 3 and MgO, while the second auxiliary consists of a combination of two kinds of Al 2 O 3 and AlN, The composition range is shown in FIG. 1, that is, the additive composition ratio of Si 3 N 4 and the first auxiliary is 85:15 to 95: 5 in mol%, and Si 3 N 4 and the second auxiliary are added. Composition ratio of agent is 90: 1 in mol%
Points A, B in FIG. 1 shown in the range 0 to 98: 2,
1400 to 1600 ° C. of a green compact or a compact made of a mixed powder consisting of an auxiliary agent in the range surrounded by C and D,
After performing primary sintering in a N 2 gas atmosphere of 1.1 atm or less so that the relative density of the sintered body becomes 96% or more and 98.5% or less, 1400 to 1700 ° C. and 10 atm or more of N 2 gas Secondary sintering was performed in the atmosphere so that the relative density of the sintered body was 99.5% or more, and α was added to the crystal phase in the obtained sintered body.
-Si 3 N 4 and β'-sialon are both included, so this is a method for obtaining a sintered body with excellent productivity, and at the same time, because of its low sintering temperature, it causes abnormal grain growth. There is no deterioration of the characteristics of the sintered body. The effect of the sintered body of the present invention to obtain excellent strength characteristics is that fine grains and equiaxed α-
By combining both Si 3 N 4 and columnarized β′-sialon crystal phases, the Young's modulus and hardness are higher than those of the conventional sintered body composed of only the columnarized β′-sialon crystal phase. Is improved. This is because it is a physical property value indicating the deformation resistance of a material, and in the case of 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
【０００５】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−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考え方は、上記の報告以
外に例えば特開昭６１−９１０６５号や特開平２−４４
０６６号に開示されているが、いずれも組成的にはＳｉ
3Ｎ4−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、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１００
ｋｇ／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’−サイアロンの間の熱膨
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 = Eγs / 4a, E; Young's modulus, γs; surface energy of fracture-, a; pre-existing crack length where γs is considered to depend on the composition and thickness of the grain boundary phase. It is advantageous to combine the crystal phases to improve the existing density of crystal grains in terms of thickness. 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 unavoidable in the process is excluded, the present invention in which the filling property is improved by fine crystal grains is effective in improving the strength in terms of E and γs. The idea of combining both α-Si 3 N 4 and columnar β′-sialon crystal phases is not limited to the above report, but is disclosed in, for example, JP-A-61-191065 and JP-A-2-44.
No. 066, but both are compositionally Si
3 N 4 -AlN-MO (M; MgO, Y 2 O 3 , CaO, etc.)
The three-component system is mainly used, and the range is such that the mechanical ratio such as strength is improved in the limited range of the addition ratio of AlN and MO of 1: 9 in mol%. As is clear from the examples, the bending strength of each sintered body is 100.
All of the methods for producing a sintered body that stably exceed kg / mm 2 are based on the hot pressing method, and industrially stable and high strength properties have not yet been achieved. In addition, these sintered bodies have a large difference in thermal expansion coefficient between α'-sialon and β'-sialon, which may cause tensile residual stress in the sintered body, which may lead to strength deterioration. There is.
The present invention is to provide an industrially stable and high-strength sintered body that is not limited to such conditions.
【０００６】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９５：５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９８：２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のは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９５：
５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Ｓｉ3Ｎ4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９
８：２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線回析のピーク
強度比が、０＜α−Ｓｉ3Ｎ4≦５０％、５０％≦β’−
サイアロン＜１００％であることがのぞましい。この析
出比がα−Ｓｉ3Ｎ4側へずれると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。一方、助
剤の添加比率については、とくに第２助剤のＡｌ2Ｏ3、
およびＡｌＮの添加比率が本発明の効果を達成するため
に重要な条件となる。すなわち、第２助剤のＡｌ2Ｏ3と
ＡｌＮの添加比率が、モル比｛ＡｌＮ／（Ａｌ2Ｏ3＋Ａ
ｌＮ）｝で２５〜７５％の範囲にあることがのぞまし
い。このモル比が２５％未満であるとβ’−サイアロン
の粒成長が顕著に現れ、焼結体の強度劣化を招き、一方
７５％を越えると焼結体中のα−Ｓｉ3Ｎ4の複合比率が
大きくなり、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。Explaining the detailed operation of the present invention, the composition range is as shown in FIG. 1, namely, Si 3 N 4 and the first range.
When the additive composition ratio of the auxiliary agent is in the range of 85:15 to 95: 5 in mol%, and the additive composition ratio of Si 3 N 4 and the second auxiliary agent is in the range of 90:10 to 98: 2 in the case of mol%. The area surrounded by points A, B, C, and D in FIG. 1 is Si 3 N 4
And the composition ratio of the first auxiliary is 85:15 in mol%, the first
If it shifts to the side of the auxiliary agent, the content of α-Si 3 N 4 is high, which causes deterioration of the strength of the sintered body, and is affected by the atmosphere during sintering, and the characteristics such as strength on the surface of the sintered body. This is because a surface layer that deteriorates is generated. The same composition ratio is 95:
This is because if it shifts from No. 5 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. On the other hand, if the additive composition ratio of Si 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. At the same time, the surface layer that deteriorates the properties such as strength is also formed on the surface of the sintered body under the influence of the atmosphere during sintering. The same composition ratio is 9
This is because if it shifts from 8: 2 to the Si 3 N 4 side, the sinterability decreases and a sufficiently dense sintered body cannot be obtained unless a pressure sintering method such as a hot pressing method is used. In order to make the effect of the present invention more remarkable, the precipitation ratio of the crystal phases of α-Si 3 N 4 and β'-sialon in the sintered body is such that the peak intensity ratio of X-ray diffraction is 0 <α-. Si 3 N 4 ≦ 50%, 50% ≦ β′−
Desirably Sialon <100%. If this precipitation ratio shifts to the α-Si 3 N 4 side, the effect of compounding the crystal phase does not sufficiently appear and the effect of improving the strength is not sufficient. On the other hand, regarding the addition ratio of the auxiliary agent, particularly, the second auxiliary agent Al 2 O 3 ,
The addition ratio of AlN and AlN is an important condition for achieving the effect of the present invention. That is, the addition ratio of Al 2 O 3 and AlN as the second auxiliary agent is the molar ratio {AlN / (Al 2 O 3 + A
1N)} is preferably in the range of 25 to 75%. If the molar ratio is less than 25%, the grain growth of β'-sialon will be prominent and the strength of the sintered body will be deteriorated. On the other hand, if it exceeds 75%, the composite of α-Si 3 N 4 in the sintered body will be deteriorated. The ratio becomes large, the effect of compounding the crystal phases does not sufficiently appear, and the effect of improving the strength is not sufficient.
【０００７】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、１４００〜１６０
０℃、１．１気圧以下のＮ2ガス雰囲気中で焼結体相対
密度が９６％以上９８．５％以下になるよう１次焼結を
おこなった後、１４００〜１７００℃、１０気圧以上の
Ｎ2ガス雰囲気中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重要である。ここで窒化
ケイ素原料として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１
４００〜１６００℃、１．１気圧以下のＮ2ガス雰囲気
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Ｎ2雰囲気下で
は１７００℃以上の温度域で昇華分解するため、加圧Ｎ
2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１４００〜１６００℃としたのは、上述した理由
の他に１４００℃未満では焼結体の緻密化が十分図れ
ず、１６００℃を超えると、二次焼結後の結晶粒の粗大
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９８．５％
以下に焼結するのは、２次焼結において焼結体の緻密化
を十分達成するためと最終焼結体の強度を高めるためで
ある。相対密度が９６％未満であると２次焼結の段階で
焼結体の緻密化が十分達成できず、９８．５％を越える
と２次焼結において結晶粒の粗大化が進行し強度劣化に
つながる。一方２次焼結条件の焼結温度を１４００〜１
７００℃としたのは、やはり１４００℃未満では焼結体
の緻密化が十分図れず、１７００℃を超えると、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
となるためである。また、２次焼結を１０気圧未満のＮ
2雰囲気下で行うと最終の焼結体が十分に緻密化しない
ため１０気圧以上が好ましい。一方得られた焼結体の相
対密度が９９．５％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。また上述した条件は、窒化
ケイ素原料粉末の製法がイミド分解法によるものである
と、さらに焼結体の強度特性を向上させるのに好まし
い。イミド分解法により得られた窒化ケイ素原料粉末は
α率が高く、結晶粒径の粒度分布も狭いため、本発明の
組成、焼結法の組合せにより、結晶相の複合化の効果が
顕著に現れる。以上により本発明の焼結体が強度特性、
及び生産性、コストに優れたものであることが明らかと
なった。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 0.7μ.
Using a silicon nitride raw material powder of m or less, 1400 to 160
After performing primary sintering in a N 2 gas atmosphere at 0 ° C. and 1.1 atm or less so that the relative density of the sintered body becomes 96% or more and 98.5% or less, 1400 to 1700 ° C. and 10 atm or more It is important to carry out secondary sintering in a N 2 gas atmosphere so that the relative density of the sintered body becomes 99% or more. Here, as a silicon nitride raw material, the α ratio is 93% or more, and the average particle size is 0.7 μm.
The reason why the silicon nitride raw material powder of m or less is required is to improve the sinterability in the low temperature range. Further, by selecting the composition range of the present invention, the sintering conditions are as follows:
It became possible in the low temperature range of 400 to 1600 ° C. and N 2 gas atmosphere of 1.1 atm or less. For this reason, the compounding of crystal grains is made up of finer crystal grains, which makes the effect remarkable, and the primary sintering is performed simultaneously by the open type continuous sintering furnace such as the pusher type or the belt type, which is excellent in productivity. Sintering becomes possible. Adding this detailed description, generally, as a sintering method of a silicon nitride-based material having excellent strength characteristics, gas pressure sintering in a so-called batch type sintering furnace is mainly used.
Since this method inevitably causes variations in temperature distribution in the furnace and variations in conditions between lots, it cannot be said that this method is sufficient as a method for stably supplying ceramic materials for applications such as mass-produced parts. Further, since silicon nitride decomposes by sublimation in a temperature range of 1700 ° C. or higher in an N 2 atmosphere at atmospheric pressure, the pressure N
It was necessary to sinter under 2 atmospheres, 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 the productivity is improved at the same time. The reason why the sintering temperature is set to 1400 to 1600 ° C. is that, for reasons other than the above, if the temperature is less than 1400 ° C., the densification of the sintered body cannot be sufficiently achieved, and if it exceeds 1600 ° C., the crystal grains after the secondary sintering are performed. Becomes noticeable, which causes deterioration and variation in strength characteristics. Further, the relative density of the primary sintered body is 96% or more and 98.5% or more.
The reason for sintering below is to achieve sufficient densification of the sintered body in the secondary sintering and to increase the strength of the final sintered body. If the relative density is less than 96%, the densification of the sintered body cannot be sufficiently achieved at the stage of secondary sintering, and if the relative density exceeds 98.5%, coarsening of crystal grains proceeds in the secondary sintering and the strength deteriorates. Lead to On the other hand, the sintering temperature under the secondary sintering conditions is 1400 to 1
The reason for setting the temperature to 700 ° C. is that if the temperature is lower than 1400 ° C., the sintered body cannot be sufficiently densified, and if the temperature exceeds 1700 ° C., coarsening of crystal grains becomes remarkable, which causes deterioration or variation in strength characteristics. is there. In addition, secondary sintering is performed under N of less than 10 atm.
Since the final sintered body is not sufficiently densified when carried out under 2 atmospheres, 10 atm or more is preferable. On the other hand, if the relative density of the obtained sintered body is less than 99.5%, the strength characteristics vary, which is not preferable. Further, the above-described conditions are preferable for further improving the strength characteristics of the sintered body when the method for producing the silicon nitride raw material powder is the imide decomposition method. Since the silicon nitride raw material powder obtained by the imide decomposition method has a high α ratio and a narrow grain size distribution of the crystal grain size, the combination of the composition of the present invention and the sintering method brings about a remarkable effect of compounding the crystal phases. .. From the above, the sintered body of the present invention has strength characteristics,
In addition, it has been clarified that it is excellent in productivity and cost.
【０００８】[0008]
実施例１ 平均粒径０．４μｍ、α結晶化率９６％、酸素量１．４
重量％のイミド分解法を製法とする窒化ケイ素原料粉末
および、平均粒径０．８μｍ、０．４μｍ、０．５μ
ｍ、０．５μｍのＹ2Ｏ3、Ａｌ2Ｏ3、ＡｌＮ、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／ｃｍ2でＣＩＰ
成形し、この成形体をＮ2ガス１気圧中で１４５０℃で
６時間、１５５０℃で３時間１次焼結した。得られた焼
結体を１５５０℃、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ＪＩＳＲ１６０１
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、ＪＩ
ＳＲ１６０１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 rate 96%, oxygen amount 1.4
Silicon nitride raw material powder produced by the imide decomposition method of weight% and average particle diameters 0.8 μm, 0.4 μm, 0.5 μ
m, 0.5 μm of Y 2 O 3 , Al 2 O 3 , AlN, and MgO powders having the composition shown in Table 1 were wet-mixed in ethanol for 100 hours in a nylon ball mill, and then dried. CIP the obtained mixed powder at 3000 kg / cm 2 .
This was compacted, and this compact was primary-sintered at 1450 ° C. for 6 hours and 1550 ° C. for 3 hours in an atmosphere of N 2 gas. The obtained sintered body was subjected to 1 at 1550 ° C. and 1000 atmospheric pressure N 2 gas atmosphere.
Secondary sintering was performed for a time. From this sintered body JIS R1601
After cutting a bending test piece equivalent to 3 mm x 4 mm x 40 mm conforming to JIS and cutting and finishing with a # 800 diamond grindstone, the tensile surface is lapped with a diamond paste of # 3000 and then JI.
In accordance with SR1601, 15 3-point bending strengths were carried out. Table 2 shows the relative density of the primary sintered body, the relative density of the secondary sintered body, the ratio of the crystal phases, the bending strength, and the Weibull coefficient. The crystal phase ratio was calculated from the peak height ratio of each crystal phase obtained by the X-ray diffraction method.
【０００９】[0009]
【表１】 [Table 1]
【００１０】[0010]
【表２】 [Table 2]
【００１１】実施例２ 市販の直接窒化法により得られた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
１４８０℃で５時間、１６００℃で２時間１次焼結した
後、１５５０℃、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。Example 2 A silicon nitride raw material powder (average particle size = 0.7 μm, α crystallization rate = 93%, oxygen amount = 1.5% by weight) obtained by a commercially available direct nitriding method was used as in Example 1. The same auxiliary agent powders were mixed, dried and molded in the same manner as in Example 1 so as to have the compositions 1 to 5 of Example 1. The compact was primarily sintered in N 2 gas at 1 atm for 1 hour at 1480 ° C. for 2 hours and at 1600 ° C. for 2 hours, and then at 1550 ° C. in a 1000 atmosphere N 2 atmosphere for 1 hour. A bending test piece according to 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.
【００１２】[0012]
【表３】 [Table 3]
【００１３】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１４５０℃で６時間、
１５５０℃で３時間１次焼結した後、連続して１５５０
℃、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。Example 3 The same raw material powder as in Example 1 was used, and the composition 1 shown in Example 1 was used.
About 5 to 5 were mixed, dried and molded by the same method. The obtained molded body was treated at 1450 ° C. for 6 hours in 1 atmosphere of N 2 gas,
After primary sintering at 1550 ° C. for 3 hours, 1550 continuously
Secondary sintering was carried out at 80 ° C. in a N 2 gas atmosphere at 80 ° C. 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. The results are shown in Table 4.
【００１４】[0014]
【表４】 [Table 4]
【００１５】実施例４ 実施例２と同様の原料粉末を、実施例１で示した組成
２、３、４、９、１５について、実施例１と同様の手法
で混合、乾燥、成形した。得られた成形体を表５に示す
条件で１次焼結した後、１６００℃、５０気圧Ｎ2ガス
雰囲気中で２時間焼結した。得られた焼結体より、実施
例１と同様の手法でＪＩＳＲ１６０１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。Example 4 The same raw material powder as in Example 2 was mixed, dried and molded in the same manner as in Example 1 for the compositions 2, 3, 4, 9 and 15 shown in Example 1. The molded body thus obtained was primarily sintered under the conditions shown in Table 5, and then sintered at 1600 ° C. in a N 2 gas atmosphere of 50 atm for 2 hours. A bending test piece according to JIS R1601 was cut out from the obtained sintered body by the same method as in Example 1 and evaluated by the same method as in Example 1.
【００１６】[0016]
【表５】 [Table 5]
【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
It is 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 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Yamakawa 1-1-1 Kunyo Kita, Itami City, Hyogo Prefecture Sumitomo Electric Industries, Ltd. Itami Works
Claims (3)
以下の窒化ケイ素原料粉末を用い、Ｓｉ3Ｎ4−第１助剤
−第２助剤の３元組成図において、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及びＡｌＮの２種より選ばれた組合わせよ
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８５：１
５から９５：５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９８：２の範囲
で示される図１中の点Ａ、Ｂ、Ｃ、Ｄで囲まれる組成範
囲助剤とからなる混合粉末より圧粉体もしくは成形体を
１４００〜１６００℃、１．１気圧以下のＮ2ガス雰囲
気中で焼結体相対密度が９６％以上９８．５％以下にな
るよう１次焼結をおこなった後、１４００〜１７００
℃、１０気圧以上のＮ2ガス雰囲気中で焼結体相対密度
が９９．５％以上になるよう２次焼結をおこない、得ら
れた焼結体中の結晶相にα−Ｓｉ3Ｎ4とβ’−サイアロ
ンの双方を含むことを特徴とする窒化ケイ素系焼結体の
製造法。1. An α ratio of 93% or more and an average particle size of 0.7 μm.
In the ternary composition diagram of Si 3 N 4 -first auxiliary agent-second auxiliary agent, the following auxiliary powder of silicon nitride was used, and the first auxiliary agent was a combination of two kinds of Y 2 O 3 and MgO. On the other hand, the second auxiliary agent is a combination selected from two kinds of Al 2 O 3 and AlN, and the composition range thereof is the range shown in FIG. 1, that is, the additive composition of Si 3 N 4 and the first auxiliary agent. The ratio is 85: 1 in mol%
5 to 95: 5 and the addition composition ratio of Si 3 N 4 and the second auxiliary agent is in the range of 90:10 to 98: 2 in mol%, and points A, B and C in FIG. , 1400 to 1600 ° C. the green compact or compacts from a mixed powder consisting of a composition range aid surrounded by D, the sintered body relative density of 96% or more in the following N 2 atmosphere 1.1 atm 98. After the primary sintering was performed so as to be 5% or less, 1400 to 1700
Secondary sintering was carried out in a N 2 gas atmosphere at 10 ° C. or higher so that the relative density of the sintered body was 99.5% or higher, and α-Si 3 N 4 was added to the crystal phase in the obtained sintered body. And a β'-sialon are contained in the silicon nitride sintered body.
ロンの結晶相の析出比がＸ線回析のピ―ク強度比が、０
％＜α−Ｓｉ3Ｎ4≦５０％、５０％＜β’−サイアロン
＜１００％であることを特徴とする請求項１記載の窒化
ケイ素系焼結体の製造法。2. The precipitation ratio of the crystal phases of α-Si 3 N 4 and β'-sialon in the sintered body is 0 and the peak intensity ratio of X-ray diffraction is 0.
The method for producing a silicon nitride based sintered body according to claim 1, wherein% <α-Si 3 N 4 ≦ 50% and 50% <β′-sialon <100%.
が、モル比｛ＡｌＮ／（Ａｌ2Ｏ3＋ＡｌＮ）｝で２５〜
７５％の範囲にあることを特徴とする請求項１記載の窒
化ケイ素系焼結体の製造法。 3. The addition ratio of Al 2 O 3 and AlN as the second auxiliary agent is 25 to 50 in terms of a molar ratio {AlN / (Al 2 O 3 + AlN)}.
The method for producing a silicon nitride-based sintered body according to claim 1, characterized in that the content is in the range of 75%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3314534A JPH05148028A (en) | 1991-11-28 | 1991-11-28 | Method for manufacturing silicon nitride sintered body |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3314534A JPH05148028A (en) | 1991-11-28 | 1991-11-28 | Method for manufacturing silicon nitride sintered body |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05148028A true JPH05148028A (en) | 1993-06-15 |
Family
ID=18054450
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3314534A Pending JPH05148028A (en) | 1991-11-28 | 1991-11-28 | Method for manufacturing silicon nitride sintered body |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05148028A (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57123865A (en) * | 1981-01-27 | 1982-08-02 | Kobe Steel Ltd | Manufacture of high density silicon nitride sintered body |
| JPS63139057A (en) * | 1986-11-28 | 1988-06-10 | 住友電気工業株式会社 | Manufacturing method of silicon nitride ceramics |
| JPS63218584A (en) * | 1987-03-05 | 1988-09-12 | 株式会社東芝 | Ceramic sintered body |
| JPH0222173A (en) * | 1988-07-08 | 1990-01-25 | Nippon Tungsten Co Ltd | Silicon nitride sintered body and manufacturing method thereof |
| JPH02167861A (en) * | 1988-12-22 | 1990-06-28 | Tosoh Corp | Production of calcined silicon nitride body |
-
1991
- 1991-11-28 JP JP3314534A patent/JPH05148028A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57123865A (en) * | 1981-01-27 | 1982-08-02 | Kobe Steel Ltd | Manufacture of high density silicon nitride sintered body |
| JPS63139057A (en) * | 1986-11-28 | 1988-06-10 | 住友電気工業株式会社 | Manufacturing method of silicon nitride ceramics |
| JPS63218584A (en) * | 1987-03-05 | 1988-09-12 | 株式会社東芝 | Ceramic sintered body |
| JPH0222173A (en) * | 1988-07-08 | 1990-01-25 | Nippon Tungsten Co Ltd | Silicon nitride sintered body and manufacturing method thereof |
| JPH02167861A (en) * | 1988-12-22 | 1990-06-28 | Tosoh Corp | Production of calcined silicon nitride body |
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