JPH10212167A - Silicon nitride-base composite sintered compact and its production - Google Patents
Silicon nitride-base composite sintered compact and its productionInfo
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- JPH10212167A JPH10212167A JP9018089A JP1808997A JPH10212167A JP H10212167 A JPH10212167 A JP H10212167A JP 9018089 A JP9018089 A JP 9018089A JP 1808997 A JP1808997 A JP 1808997A JP H10212167 A JPH10212167 A JP H10212167A
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、室温から高温まで
の強度特性に優れると共に破壊靱性、耐クリープ特性に
優れ、特にピストン、シリンダー、バルブ、カムローラ
ー、ロッカーアーム、ピストンリング、ピストンピンな
どの自動車用部品や、タービンロータ、タービンブレー
ド、ノズル、コンバスタ、スクロール、ノズルサポー
ト、シールリング、スプリングリング、ディフューザ、
ダクトなどのガスタービンエンジン用部品に好適に使用
される窒化珪素質複合焼結体およびその製造方法に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is excellent in strength characteristics from room temperature to high temperature, excellent in fracture toughness, and excellent in creep resistance, especially for pistons, cylinders, valves, cam rollers, rocker arms, piston rings, piston pins, etc. Automotive parts, turbine rotors, turbine blades, nozzles, combustors, scrolls, nozzle supports, seal rings, spring rings, diffusers,
The present invention relates to a silicon nitride composite sintered body suitably used for a gas turbine engine component such as a duct, and a method for producing the same.
【０００２】[0002]
【従来技術】窒化珪素質焼結体は、従来から、強度、硬
度、熱的化学的安定性に優れることからエンジニアリン
グセラミックスとして、特に熱機関構造用材料としてそ
の応用が進められている。このような窒化珪素質焼結体
は、窒化珪素粉末に対して周期律表第３ａ族元素酸化物
等の焼結助剤を添加混合し、成形後、非酸化性雰囲気中
で１５００〜２０００℃の温度にて焼成することにより
得られている。ところが、窒化珪素質焼結体は、優れた
特性を有する反面、高温において強度及びクリープ強度
が低下するという問題を有している。この高温特性の劣
化という問題に対してこれまで、焼結助剤の改良や焼成
雰囲気や焼成パターン等を変更することにより改善が進
められてきたが、決定的な対策には到っていないのが現
状である。2. Description of the Related Art Conventionally, silicon nitride-based sintered bodies have been applied as engineering ceramics, particularly as heat engine structural materials, because of their excellent strength, hardness and thermal and chemical stability. Such a silicon nitride-based sintered body is obtained by adding and mixing a sintering aid such as an oxide of a Group 3a element in the periodic table to silicon nitride powder, forming the mixture, and then forming the mixture at 1500 to 2000 ° C. in a non-oxidizing atmosphere. At the following temperature. However, while the silicon nitride sintered body has excellent characteristics, it has a problem that strength and creep strength are reduced at high temperatures. Up to now, the problem of deterioration of the high-temperature properties has been improved by improving the sintering aid and changing the firing atmosphere and firing pattern, but no definitive measures have been reached. Is the current situation.
【０００３】一方、炭化珪素質焼結体は、窒化珪素質焼
結体において見られるような強度の高温での劣化がほと
んどないという優れた性質を有するが、絶対的な強度が
低いとともに靱性に乏しいという問題がある。[0003] On the other hand, a silicon carbide-based sintered body has an excellent property of hardly deteriorating at a high temperature as in a silicon nitride-based sintered body, but has a low absolute strength and a low toughness. There is a problem of scarcity.
【０００４】そこで、最近に到り、窒化珪素に対して炭
化珪素を添加して焼成した複合焼結体が特開平３−５３
７４号、特開平３−１３１５７１号などにて提案されて
いる。また、この複合焼結体は、炭化珪素を分散含有す
ることにより系の焼結性が低下することから、通常Ｙ2
Ｏ3 等の希土類元素酸化物の他にＡｌ2 Ｏ3 等を添加す
ることにより焼結性を高め、高密度化を図っている。Therefore, recently, a composite sintered body obtained by adding silicon carbide to silicon nitride and firing the same has been disclosed in Japanese Patent Laid-Open No. 3-53.
74, and Japanese Patent Application Laid-Open No. 3-131571. In addition, since this composite sintered body contains silicon carbide in a dispersed manner, the sinterability of the system is reduced, and therefore, usually Y 2
Enhance sinterability by the addition of Al 2 O 3 or the like in addition to the O rare earth oxide such as 3, thereby achieving a high density.
【０００５】[0005]
【発明が解決しようとする課題】上記の先行技術によれ
ば、窒化珪素に対して炭化珪素を添加することにより、
靱性を窒化珪素質焼結体に比較して大きくすることは出
来る。しかし、本発明者等は上記の焼結体に対して高温
特性についてさらに詳細に検討したところ、高温での耐
クリープ性が悪いという問題があることが分かった。こ
のような特性を有する焼結体を例えばタービンロータに
適用した場合に、応力負荷下で長時間作動させることに
より変形または破壊に至るために実用化が大きく阻害さ
れる要因となる。According to the above prior art, by adding silicon carbide to silicon nitride,
The toughness can be increased as compared with the silicon nitride sintered body. However, the present inventors have examined the high-temperature characteristics of the above sintered body in more detail, and found that there is a problem that the creep resistance at high temperatures is poor. When a sintered body having such characteristics is applied to, for example, a turbine rotor, it is deformed or broken by operating for a long time under a stress load, which is a factor greatly hindering practical use.
【０００６】これは、焼結体中の粒界の状態が大きく起
因するものと考えられるものの具体的な対策がなく、窒
化珪素と炭化珪素の複合化による特性の向上効果が十分
に発揮されていないのが現状であった。This is thought to be largely due to the state of the grain boundaries in the sintered body, but there is no specific countermeasure, and the effect of improving the characteristics by combining silicon nitride and silicon carbide is sufficiently exhibited. There was no current situation.
【０００７】また、特開昭63-100067 号に記載のように
粒界相を２種以上の希土類元素で複合酸化物を形成させ
ると共融点が低下するため、高温での耐クリープ特性も
低いものであった。Further, as described in JP-A-63-100067, when a grain boundary phase is formed of a composite oxide with two or more kinds of rare earth elements, the eutectic point is lowered, so that the creep resistance at high temperatures is also low. Was something.
【０００８】よって本発明は、室温から高温までの自動
車部品やガスタービンエンジン用等で使用されるに十分
な高温強度特性、破壊靱性を有するとともに、１５００
℃での耐クリープ特性に優れた窒化珪素質複合焼結体と
その製造方法を提供することを目的とするものである。Accordingly, the present invention has high-temperature strength characteristics and fracture toughness sufficient for use in automobile parts from room temperature to high temperature, for gas turbine engines, etc., and at 1500
An object of the present invention is to provide a silicon nitride composite sintered body having excellent creep resistance at a temperature of ° C and a method for producing the same.
【０００９】[0009]
【課題を解決するための手段】本発明者等は、前述した
ように室温、高温における強度および破壊靱性、耐クリ
ープ性に対して検討を加えたところ、複合焼結体におけ
る粒界の組成が大きく特性に関与していることを見出
し、さらに検討を重ねた結果、窒化珪素と、Ｔａ、Ｎ
ｂ、Ｍｏ、Ｗの珪化物及びＳｉＣから選ばれる少なくと
も１種の硬質粒子を含有し、さらに焼結助剤としての周
期律表第３ａ族元素酸化物として、Ｌｕ2 Ｏ3 を含有す
る複合焼結体中において、窒化珪素結晶を平均粒径５μ
ｍ以下、平均アスペクト比が５以上の結晶粒子として、
前記硬質粒子を平均粒径１〜５μｍの結晶粒子として存
在させるとともに、前記不純物的酸素及びＬｕが窒化珪
素結晶粒子及び硬質粒子の粒界に主としてアパタイト、
ＹＡＭ及びワラストナイトの群から選ばれる少なくとも
１種の結晶相として存在させることにより、高温におい
て優れた耐クリープ性を有するとともに、高強度の焼結
体が得られることを見いだした。Means for Solving the Problems As described above, the present inventors have examined the strength at room temperature and high temperature, the fracture toughness, and the creep resistance. As a result of finding that it is greatly involved in the characteristics and further study, it was found that silicon nitride, Ta, N
b, Mo, W, at least one type of hard particles selected from silicides and SiC, and further containing Lu 2 O 3 as an oxide of a Group 3a element of the periodic table as a sintering aid. In the sintered body, the silicon nitride crystal has an average particle size of 5 μm.
m or less, as crystal grains having an average aspect ratio of 5 or more,
The hard particles are present as crystal particles having an average particle size of 1 to 5 μm, and the impurity oxygen and Lu are mainly apatite at grain boundaries of the silicon nitride crystal particles and the hard particles.
It has been found that by having at least one crystal phase selected from the group of YAM and wollastonite, a sintered body having excellent creep resistance at high temperatures and high strength can be obtained.
【００１０】[0010]
【発明の実施の形態】本発明の窒化珪素質複合焼結体
は、窒化珪素成分と、Ｔａ、Ｎｂ、Ｍｏ、Ｗの珪化物及
びＳｉＣから選ばれる少なくとも１種の硬質粒子を含有
し、さらに窒化珪素成分中には、焼結助剤としてＬｕ
（ルテチウム）化合物と不純物的酸素を含む。ここで不
純物的酸素とは、焼結体中の全酸素量から添加物として
Ｌｕ2 Ｏ3等の周期律表第３ａ族元素化合物中に化学量
論的に含まれる酸素を差し引いた残りの酸素量であり、
そのほとんどは窒化珪素原料に含まれる酸素、あるいは
添加される酸化珪素として混入するものであり、これら
は全てＳｉ−Ｏの化学結合を含む、例えばＳｉＯ2 とし
て存在すると考えられる。BEST MODE FOR CARRYING OUT THE INVENTION The silicon nitride composite sintered body of the present invention contains a silicon nitride component and at least one kind of hard particles selected from silicides of Ta, Nb, Mo, W and SiC. Lu in the silicon nitride component as a sintering aid
Contains (lutetium) compound and impurity oxygen. Here, the term "impurity oxygen" refers to the remaining oxygen obtained by subtracting the stoichiometric oxygen contained in the Group 3a element compound of the periodic table such as Lu 2 O 3 as an additive from the total amount of oxygen in the sintered body. Quantity
Most of them are mixed as oxygen contained in the silicon nitride raw material or added silicon oxide, and all of them are considered to exist as, for example, SiO 2 containing a chemical bond of Si—O.
【００１１】本発明の窒化珪素質焼結体は、組織的に
は、窒化珪素結晶相を主相とするものであり、それらは
平均粒径５μｍ以下、特に３μｍ以下、平均アスペクト
比５以上、特に７以上の針状で微細な結晶のβ−Ｓｉ3
Ｎ4 からなる。また、窒化珪素結晶相の他には、硬質粒
子結晶相が平均粒径１〜５μｍの結晶粒子として存在す
る。また、これらの結晶相間には粒界が存在する。この
ように、窒化珪素結晶相を針状の微細な結晶として存在
させることにより、焼結体の強度および靱性を高めるこ
とができ、平均粒径が５μｍよりも大きい、あるいは平
均アスペクト比が５よりも小さいと、高温強度および靱
性の向上効果が十分に発揮されない。さらに、硬質粒子
結晶相の平均粒径が１μｍよりも小さいと破壊靱性向上
の効果が小さく、５μｍよりも大きいと焼結性を阻害し
焼結不足を招く等の不都合が生じる。The silicon nitride sintered body of the present invention is structurally composed mainly of a silicon nitride crystal phase, and has an average particle size of 5 μm or less, particularly 3 μm or less, and an average aspect ratio of 5 or more. In particular, β-Si 3 of 7 or more needle-like and fine crystals
Consisting of N 4. In addition to the silicon nitride crystal phase, a hard particle crystal phase exists as crystal particles having an average particle size of 1 to 5 μm. In addition, grain boundaries exist between these crystal phases. As described above, by allowing the silicon nitride crystal phase to exist as fine needle-like crystals, the strength and toughness of the sintered body can be increased, and the average grain size is larger than 5 μm, or the average aspect ratio is larger than 5. If it is too small, the effect of improving high-temperature strength and toughness is not sufficiently exhibited. Further, when the average particle size of the hard particle crystal phase is smaller than 1 μm, the effect of improving fracture toughness is small, and when the average particle size is larger than 5 μm, inconveniences such as impairing sintering and causing insufficient sintering occur.
【００１２】また、窒化珪素結晶および硬質粒子結晶相
の粒界には、少なくともＬｕ、Ｓｉ（珪素）、Ｏ（酸
素）およびＮ（窒素）からなる結晶（以下、Ｌｕ−Ｓｉ
−Ｏ−Ｎ系結晶）が存在し、具体的には、Ｌｕ4 Ｓｉ2
Ｏ7 Ｎ2 で表されるＹＡＭ、Ｌｕ10Ｓｉ7 Ｏ23Ｎ4 で表
されるアパタイト、ＬｕＳｉＯ2 Ｎで表されるワラスト
ナイトのうちの少なくとも１種の結晶相が存在する。な
お、粒界相には上記の結晶相以外に結晶化が十分でない
場合などにおいて上記の元素を含むガラス相が存在する
場合がある。このようなガラス相が存在すると、高温で
の機械的特性を若干低下させる場合があるが、耐酸化性
及び破壊靱性に与える影響は小さいため、Ｘ線回折など
で前述した結晶相が明らかに検出されるレベルであれば
特に問題はない。Further, at the grain boundaries of the silicon nitride crystal and the hard particle crystal phase, a crystal (hereinafter referred to as Lu-Si) composed of at least Lu, Si (silicon), O (oxygen) and N (nitrogen).
—ON-based crystal), specifically, Lu 4 Si 2
At least one crystal phase of YAM represented by O 7 N 2 , apatite represented by Lu 10 Si 7 O 23 N 4 , and wollastonite represented by LuSiO 2 N is present. In addition, a glass phase containing the above element may be present in the grain boundary phase when the crystallization is not sufficient other than the above crystal phase. The presence of such a glass phase may slightly decrease the mechanical properties at high temperatures, but has little effect on oxidation resistance and fracture toughness, so that the above-mentioned crystal phase is clearly detected by X-ray diffraction or the like. There is no particular problem as long as it is at the required level.
【００１３】本発明の複合焼結体は、組成上は、窒化珪
素、Ｌｕ2 Ｏ3 および不純物的酸素からなる窒化珪素成
分１００重量部に対して、Ｔａ、Ｎｂ、Ｍｏ、Ｗの珪化
物及びＳｉＣから選ばれる少なくとも１種の硬質粒子を
０. ５〜２５重量部の割合で含有する。この硬質粒子成
分量を上記の範囲に限定したのは、硬質粒子成分量が
０. ５重量部より少ないと、窒化珪素と硬質粒子の複合
化による高温特性、破壊靱性および耐クリープ特性の向
上効果が望めず、２５重量部を越えると焼結性が低下し
強度が劣化するためである。なお、特性の点からは硬質
粒子成分量は上記窒化珪素成分１００重量部に対して１
〜１０重量部であることが望ましい。The composite sintered body of the present invention is characterized in that, based on the composition, a silicide of Ta, Nb, Mo, W and 100 parts by weight of a silicon nitride component comprising silicon nitride, Lu 2 O 3 and impurity oxygen are used. At least one kind of hard particles selected from SiC is contained in a ratio of 0.5 to 25 parts by weight. The reason why the amount of the hard particles is limited to the above range is that when the amount of the hard particles is less than 0.5 part by weight, the effect of improving the high temperature properties, fracture toughness and creep resistance by combining silicon nitride and the hard particles is obtained. Is not expected, and if it exceeds 25 parts by weight, sinterability is reduced and strength is deteriorated. In terms of characteristics, the amount of the hard particle component is 1 to 100 parts by weight of the silicon nitride component.
Desirably, the amount is from 10 to 10 parts by weight.
【００１４】また、窒化珪素成分の組成としては、窒化
珪素を７０〜９９モル％、特に８５〜９７モル％と、Ｌ
ｕをＬｕ2 Ｏ3 換算で０. ５〜１０モル％、特に１〜７
モル％と、残部が不純物的酸素からなり、特に不純物的
酸素は、酸化珪素換算で１〜２０モル％、特に２〜１４
モル％とから構成される。これは、窒化珪素量が７０モ
ル％より少ないと高温強度が発揮されず、上記Ｌｕ量が
０．５モル％未満では緻密化が不十分であり、１０モル
％を越えると高温強度及び高温耐クリープ性が劣化す
る。また、不純物的酸素が１モル％より少ないと粒界に
窒化珪素とＬｕ2Ｏ3 との化合物であるメリライトなど
の高温耐酸化性の小さい化合物が生成されやすくなり、
２０モル％を越えると粒界相の体積分率が増加し高温特
性が劣化しやすくなるためである。The composition of the silicon nitride component is as follows: 70 to 99 mol%, particularly 85 to 97 mol%, of silicon nitride;
is 0.5 to 10 mol%, particularly 1 to 7 mol% in terms of Lu 2 O 3.
Mol%, and the balance consists of impurity oxygen. Particularly, impurity oxygen is 1 to 20 mol%, particularly 2 to 14 mol% in terms of silicon oxide.
Mol%. If the amount of silicon nitride is less than 70 mol%, high-temperature strength is not exhibited. If the amount of Lu is less than 0.5 mol%, densification is insufficient. The creep property deteriorates. On the other hand, if the amount of impurity oxygen is less than 1 mol%, a compound having low resistance to high-temperature oxidation such as melilite, which is a compound of silicon nitride and Lu 2 O 3 , is likely to be formed at the grain boundary.
If the content exceeds 20 mol%, the volume fraction of the grain boundary phase increases, and the high-temperature characteristics tend to deteriorate.
【００１５】さらに、本発明によれば、上記窒化珪素成
分において、Ｌｕを含む周期律表第３ａ族元素の酸化物
換算（ＲＥ2 Ｏ3 ）に対する不純物的酸素のＳｉＯ2 換
算量のモル比（ＳｉＯ2 ／ＲＥ2 Ｏ3 ）が２未満、特に
１〜１．９、さらには１．２〜１．８であることが望ま
しい。これは、上記モル比が２以上では、前記ＹＡＭ、
アパタイト、ワラストナイトなどの結晶相の析出が望め
ず、その結果、高温強度が低下するとともに耐クリープ
性も劣化するためである。Further, according to the present invention, in the silicon nitride component, the molar ratio of the amount of impurity oxygen in terms of SiO 2 with respect to the oxide (RE 2 O 3 ) of a Group 3a element of the periodic table containing Lu (RE 2 O 3 ). (SiO 2 / RE 2 O 3 ) is preferably less than 2, especially 1 to 1.9, more preferably 1.2 to 1.8. This is because when the molar ratio is 2 or more, the YAM,
This is because precipitation of crystal phases such as apatite and wollastonite cannot be expected, and as a result, high-temperature strength is reduced and creep resistance is also deteriorated.
【００１６】また本発明によれば、周期律表第３ａ族元
素としては、ＬｕのみからなりＬｕ以外の他の周期律表
第３ａ族元素は存在しないことが最もよい。これは、周
期律表第３ａ族元素の中で最もイオン半径の小さいＬｕ
を選択することにより、粒界相に析出する結晶相の融点
を高めることができる結果、他の周期律表第３ａ族元素
に比較して高温強度および耐クリープ特性が飛躍的に向
上することができる。しかし、現実的にはＬｕ以外の周
期律表第３ａ族元素の幾分かの混入がある。その場合、
Ｌｕは、全周期律表第３ａ族元素のうちの９３モル％以
上、特に９７モル％以上を占めることが望ましい。これ
は、Ｌｕ以外の他の周期律表第３ａ族元素が共存する
と、Ｌｕ単独系に比較して共融点が低下し、その結果、
焼結体の耐クリープ特性が劣化するためである。なお、
Ｌｕ以外の周期律表第３ａ族元素としては、Ｙ、Ｙｂ、
Ｅｒ、Ｄｙ、Ｈｏ、Ｔｂ、ＴｍおよびＳｃ等が挙げられ
る。このように、Ｌｕ以外に他の周期律表第３ａ族元素
を上記の比率で含んでいてもよいが、その場合、焼結体
全量中、Ｌｕ量は酸化物換算で０．５モル％を下回らな
いように制御することが必要である。Further, according to the present invention, it is most preferable that the element of Group 3a of the periodic table is composed of only Lu and that there is no other Group 3a element of the periodic table other than Lu. This is because Lu has the smallest ionic radius among Group 3a elements of the periodic table.
As a result, the melting point of the crystal phase precipitated in the grain boundary phase can be increased, and as a result, the high-temperature strength and the creep resistance can be dramatically improved as compared with other Group 3a elements of the periodic table. it can. However, in reality, there is some mixing of Group 3a elements of the periodic table other than Lu. In that case,
Lu preferably occupies 93 mol% or more, particularly 97 mol% or more, of the Group 3a elements of the entire periodic table. This is because, when other Group 3a elements of the periodic table other than Lu coexist, the eutectic point is lower than that of Lu alone, and as a result,
This is because the creep resistance of the sintered body deteriorates. In addition,
As elements other than Lu in Group 3a of the periodic table, Y, Yb,
Er, Dy, Ho, Tb, Tm, Sc and the like. As described above, other elements belonging to Group 3a of the periodic table other than Lu may be contained in the above ratio. In this case, the amount of Lu in the total amount of the sintered body is 0.5 mol% in terms of oxide. It is necessary to control so as not to fall below.
【００１７】また、本発明によれば、Ａｌ、Ｍｇ、Ｆｅ
等の酸化物は、粒界にて低融点の酸化物を形成しこれに
より粒界の結晶化が阻害されるとともに高温強度および
耐クリープ特性を劣化させるため、酸化物換算による合
量で１重量％以下、特に０.５重量％以下、さらに望ま
しくは０. １重量％以下に制御することが望ましい。According to the present invention, Al, Mg, Fe
Oxides form a low melting point oxide at the grain boundaries, which hinders the crystallization of the grain boundaries and degrades the high-temperature strength and creep resistance properties. %, Particularly preferably 0.5% by weight or less, more preferably 0.1% by weight or less.
【００１８】次に、本発明の窒化珪素質複合材料を製造
する場合の方法について説明すると、まず窒化珪素成分
を形成する出発原料として、窒化珪素粉末、Ｌｕ2 Ｏ3
粉末、場合によっては、Ｌｕ以外の周期律表第３ａ族元
素酸化物粉末、あるいは場合により酸化珪素粉末を添加
してなる。また添加形態としてＬｕ2 Ｏ3 とＳｉＯ2か
らなる化合物を用いることもできる。用いられる窒化珪
素粉末は、α型、β型のいずれでも使用することがで
き、その粒子は０．４〜１．２μｍ、陽イオン不純物量
は１重量％以下、特に０. ５重量％以下、不純物酸素量
が０. ５〜2.０重量％が適当であり、直接窒化法、イミ
ド分解法などのいずれの製法によるものであってもかま
わない。Next, the method for producing the silicon nitride composite material of the present invention will be described. First, as a starting material for forming a silicon nitride component, silicon nitride powder, Lu 2 O 3
A powder, in some cases, a powder of an element oxide of a Group 3a element of the periodic table other than Lu, or a silicon oxide powder in some cases. In addition, a compound composed of Lu 2 O 3 and SiO 2 can be used as an addition form. The silicon nitride powder to be used may be any of α-type and β-type, the particles of which are 0.4 to 1.2 μm, the amount of cationic impurities is 1% by weight or less, particularly 0.5% by weight or less, The amount of impurity oxygen is suitably 0.5 to 2.0% by weight, and any method such as a direct nitriding method or an imide decomposition method may be used.
【００１９】上記の原料は、窒化珪素を７０〜９９モル
％と、Ｌｕを酸化物換算で０．５〜１０モル％と、残部
が不純物的酸素からなる。なお、Ｌｕは、全周期律表第
３ａ族元素のうち、９３％以上、特に９７％以上の割合
を満足するように、他の周期律表第３ａ族元素により置
換することも許容される。そして、前記不純物的酸素の
ＳｉＯ2 換算量の全周期律表第３ａ族元素の酸化物換算
量（ＲＥ2 Ｏ3 ）に対するモル比（ＳｉＯ2 ／ＲＥ2 Ｏ
3 ）が２未満、特に１〜１．９、さらには１．２〜１．
８となるように調整する。この時、ＳｉＯ2 ／ＲＥ2 Ｏ
3 モル比は、窒化珪素粉末中に不可避に含まれる不純物
酸素、製造過程で吸着される酸素分等を考慮して制御さ
れ、場合によってはＳｉＯ2 粉末を添加して調整され
る。The above-mentioned raw materials are composed of 70 to 99 mol% of silicon nitride, 0.5 to 10 mol% of Lu in terms of oxide, and the balance of impurity oxygen. Lu may be replaced with another Group 3a element of the periodic table so that Lu satisfies the ratio of 93% or more, particularly 97% or more, of the group 3a elements of the entire periodic table. Then, the molar ratio (SiO 2 / RE 2 O) of the amount of the impurity oxygen in terms of SiO 2 to the amount in terms of the oxide of the group 3a element of the entire periodic table (RE 2 O 3 ) (RE 2 O 3 ).
3 ) is less than 2, especially 1 to 1.9, more preferably 1.2 to 1.
Adjust so that it becomes 8. At this time, SiO 2 / RE 2 O
The 3 molar ratio is controlled in consideration of impurity oxygen inevitably contained in the silicon nitride powder, oxygen adsorbed in the production process, and the like, and may be adjusted by adding SiO 2 powder in some cases.
【００２０】また、上記窒化珪素成分１００重量部に対
して、平均粒径が１〜５μｍのＴａ、Ｎｂ、Ｍｏおよび
Ｗの珪化物、及び炭化珪素から選ばれる少なくとも１種
の硬質粒子粉末を０．５〜２５重量部の割合で添加す
る。なお、珪化物としては、焼結過程で珪化物を生成し
得る酸化物等の化合物を添加してもよい。硬質粒子粉末
として、具体的には、ＴａＳｉ2 、ＮｂＳｉ2 、ＭｏＳ
ｉ2 、ＷＳｉ2 、ＳｉＣ等が挙げられる。Further, at least one type of hard particle powder selected from silicides of Ta, Nb, Mo and W having an average particle diameter of 1 to 5 μm and silicon carbide is added to 100 parts by weight of the silicon nitride component. 0.5 to 25 parts by weight. Incidentally, as the silicide, a compound such as an oxide capable of forming a silicide in the sintering process may be added. As the hard particle powder, specifically, TaSi 2 , NbSi 2 , MoS
i 2 , WSi 2 , SiC and the like.
【００２１】窒化珪素成分および硬質粒子は、振動ミ
ル、回転ミル、バレルミルなどで十分に混合した後、混
合粉末を所望の成形手段、例えば、金型プレス、鋳込み
成形、排泥成形、押し出し成形、射出成形、冷間静水圧
プレス等により任意の形状に成形する。After the silicon nitride component and the hard particles are sufficiently mixed by a vibration mill, a rotary mill, a barrel mill, or the like, the mixed powder is molded by a desired molding means, for example, die pressing, casting, sludge molding, extrusion molding, or the like. It is formed into an arbitrary shape by injection molding, cold isostatic pressing or the like.
【００２２】次に、この成形体を窒素を含む非酸化性雰
囲気中で１６００〜１８００℃で一次保持して窒化珪素
結晶を柱状化させた後、次いで１８００℃よりも高く、
望ましくは２０００℃以下の温度で焼結させる。この時
の窒化珪素の一次保持により、平均粒径５μｍ以下、平
均アスペクト比が５以上の窒化珪素結晶粒子を生成させ
ることができる。従って、この一次保持が行われない
と、平均粒径が５μｍを越えたり、平均アスペクト比が
５よりも小さい粒状の窒化珪素結晶となってしまい、高
い強度と靱性が得られない。Next, the molded body is primarily held at 1600 to 1800 ° C. in a non-oxidizing atmosphere containing nitrogen to columnarize the silicon nitride crystal, and then higher than 1800 ° C.
Desirably, sintering is performed at a temperature of 2000 ° C. or less. At this time, silicon nitride crystal grains having an average particle diameter of 5 μm or less and an average aspect ratio of 5 or more can be generated by primary holding of silicon nitride. Therefore, if this primary holding is not performed, the average grain size exceeds 5 μm, or the silicon nitride becomes a granular silicon nitride crystal having an average aspect ratio smaller than 5, and high strength and toughness cannot be obtained.
【００２３】この時の焼成雰囲気としては、焼成温度に
おいて窒化珪素が分解しないような窒素ガス圧力に設定
することが必要であり、そのためには、雰囲気中の窒素
ガス圧力を、窒化珪素分解平衡圧以上、望ましくは、一
次保持を０．５〜５気圧、二次保持時に５気圧を越える
圧力に設定することが望ましく、さらには、雰囲気中に
上記の窒素ガスに加え、ＳｉＯガスを発生させておくこ
とが望ましい。このＳｉＯガスは、ＳｉＯ2 粉末等を焼
成炉内に配設することにより発生させることができる。
これは、焼成時にＳｉＯガスが存在しないと焼結体表面
が分解しやすくなり、メリライトが生成し焼結体の耐酸
化性を劣化させてしまうためである。At this time, it is necessary to set the firing atmosphere to a nitrogen gas pressure at which the silicon nitride does not decompose at the firing temperature. For this purpose, the nitrogen gas pressure in the atmosphere is set to the silicon nitride decomposition equilibrium pressure. As described above, it is desirable to set the primary holding pressure to 0.5 to 5 atm and to set the pressure to more than 5 atm during the secondary holding. Further, in addition to the above nitrogen gas in the atmosphere, the SiO gas is generated. It is desirable to keep. This SiO gas can be generated by disposing SiO 2 powder or the like in a firing furnace.
This is because the surface of the sintered body is easily decomposed if no SiO gas is present at the time of sintering, so that melilite is generated and the oxidation resistance of the sintered body is deteriorated.
【００２４】さらに、上記のようにして作製された焼結
体に対して、ボイドを低減することを目的として窒素、
アルゴンなどのガスを用いて１０００気圧以上の圧力下
で１６００〜１９００℃の温度で焼成する熱間静水圧焼
成（ＨＩＰ）処理することも可能である。Further, the sintered body produced as described above is subjected to nitrogen and nitrogen for the purpose of reducing voids.
It is also possible to perform a hot isostatic firing (HIP) process of firing at a temperature of 1600 to 1900 ° C. under a pressure of 1000 atm or more using a gas such as argon.
【００２５】さらに、上記の焼成後の冷却過程で降温速
度３００℃／ｈｒ以下の速度で徐冷するか、または焼結
体を１０００〜１４００℃の非酸化性雰囲気で熱処理す
ることにより粒界の結晶化を高め特性の改善を行うこと
が出来る。Further, in the cooling process after the above-mentioned calcination, the temperature is slowly cooled at a rate of 300 ° C./hr or less, or the sintered body is heat-treated in a non-oxidizing atmosphere at 1000 to 1400 ° C. to reduce the grain boundary. The crystallization can be enhanced and the characteristics can be improved.
【００２６】上記の製造方法において、製品に対して高
い寸法精度が要求される場合には、窒化珪素粉末の一部
または全部を珪素粉末に置き換えて成形体を作製し、こ
れを窒素含有雰囲気中、８００〜１５００℃で窒化処理
してα−窒化珪素に変換して成形体密度を高めたうえ
で、前述した焼成条件で焼成することにより、焼成時の
収縮を小さくすることが出来る。In the above manufacturing method, when high dimensional accuracy is required for a product, a part of or all of the silicon nitride powder is replaced with silicon powder to produce a compact, which is then placed in a nitrogen-containing atmosphere. After the nitriding treatment at 800 to 1500 ° C. to convert into α-silicon nitride to increase the density of the compact, and then firing under the above-described firing conditions, shrinkage during firing can be reduced.
【００２７】本発明によれば、窒化珪素質焼結体の粒界
を構成する周期律表第３ａ族元素として少なくともＬｕ
を選択することにより、従来から用いられている他の周
期律表第３ａ族元素に比較して高温特性を改善すること
ができる。このような優れた作用が発揮されるメカニズ
ムは、Ｌｕはランタノイド系の中で最もイオン半径が小
さく、他の元素との結合力が大きいため高温での機械的
特性や、クリープの主因である粒界のすべり現象が小さ
く、また酸素の拡散が小さいため、耐酸化性も他の周期
律表第３ａ族元素より優れていると考えられる。According to the present invention, at least Lu is used as a Group 3a element of the periodic table constituting the grain boundary of the silicon nitride based sintered body.
By selecting, it is possible to improve high-temperature characteristics as compared with other conventionally used Group 3a elements of the periodic table. The mechanism by which such an excellent action is exhibited is that Lu has the smallest ionic radius in the lanthanoid system and has a large bonding force with other elements, so that the mechanical properties at high temperatures and the granularity that is the main cause of creep are high. Since the slip phenomenon of the field is small and the diffusion of oxygen is small, it is considered that the oxidation resistance is superior to other Group 3a elements in the periodic table.
【００２８】また、焼結体の耐クリープ性を決定するの
は、焼結体の粒界相の粒界の特性によるものであり、本
発明によれば、ＹＡＭ、アパタイト、ワラストナイトか
ら選ばれる少なくとも１種の結晶相を析出させることに
より、これらの結晶相が高温雰囲気でも非常に安定であ
ることから、優れた高温強度と耐クリープ性が発揮され
る。The creep resistance of the sintered body is determined by the characteristics of the grain boundary of the grain boundary phase of the sintered body. According to the present invention, the material is selected from YAM, apatite and wollastonite. By precipitating at least one type of crystal phase, these crystal phases are very stable even in a high-temperature atmosphere, so that excellent high-temperature strength and creep resistance are exhibited.
【００２９】さらに、硬質粒子は、粒成長を適度に抑制
させる効果を有し、これらの結晶粒子を微細な粒子とし
てそれぞれ分散させることにより、通常の窒化珪素質焼
結体での大きな結晶粒子の存在により破壊が生じる現象
を極力低減することができ高温における抗折強度を大き
く向上することができる。さらに、硬質粒子はクラック
の進展を妨げる効果があり、破壊靱性の向上に寄与す
る。Further, the hard particles have an effect of appropriately suppressing the grain growth, and by dispersing these crystal particles as fine particles, respectively, the large crystal particles in a normal silicon nitride sintered body are dispersed. The phenomenon of destruction due to the presence can be reduced as much as possible, and the transverse rupture strength at high temperatures can be greatly improved. Further, the hard particles have an effect of inhibiting the progress of cracks, and contribute to the improvement of fracture toughness.
【００３０】[0030]
【実施例】原料粉末として窒化珪素粉末（ＢＥＴ比表面
積９ｍ2 ／ｇ、α率９８％以上、酸素量１. １重量％、
Ａｌ、Ｍｇ、Ｃａ、Ｆｅなどの陽イオン金属不純物量３
０ｐｐｍ以下）と、平均粒径が０．５〜７μｍの表１の
硬質粒子と、純度が９９％以上または９６％のＬｕ2 Ｏ
3 粉末と、純度９９％以上のＬｕ以外の周期律表第３ａ
族元素酸化物粉末および純度９９．９％以上の酸化珪素
粉末を用いて、これらを表１の成形体組成となるように
秤量混合し、メタノールを溶媒として窒化珪素ボールを
用いて１２０時間回転ミルで混合粉砕し、スラリーを乾
燥後、直径６０ｍｍ、厚み２０ｍｍの形状に３ｔ／ｃｍ
2 の圧力でラバープレス成形、そしてかかる成形体を表
１に示す焼成条件にて窒素ガス圧（ＧＰＳ）焼成した。
ＧＰＳ焼成では、一次焼成温度でＮ2 １気圧で１０時間
保持し、さらに二次焼成温度でＮ2 １０気圧で５時間保
持した。さらに、ＧＰＳ＋ＨＩＰは、上記ＧＰＳ焼成後
に１７００℃、窒素圧２０００気圧で１時間熱間静水圧
焼成したものである。EXAMPLES Silicon nitride powder (BET specific surface area 9 m 2 / g, α rate 98% or more, oxygen content 1.1% by weight,
Amount of cationic metal impurities such as Al, Mg, Ca, Fe, etc. 3
0 ppm or less), the hard particles of Table 1 having an average particle size of 0.5 to 7 μm, and Lu 2 O having a purity of 99% or more or 96%.
3 Powder and Periodic Table 3a other than Lu with a purity of 99% or more
A powder of a Group III element oxide and a silicon oxide powder having a purity of 99.9% or more were weighed and mixed so as to have a molded body composition shown in Table 1, and were rotated for 120 hours using silicon nitride balls with methanol as a solvent. After mixing and pulverizing, the slurry is dried, and 3 t / cm in a shape having a diameter of 60 mm and a thickness of 20 mm.
Rubber press molding was performed at a pressure of 2 , and the molded body was fired under nitrogen gas pressure (GPS) under the firing conditions shown in Table 1.
In the GPS firing, the primary firing temperature was maintained at 1 atm of N 2 for 10 hours, and the secondary firing temperature was maintained at 10 atm of N 2 for 5 hours. Further, the GPS + HIP is obtained by hot isostatic firing at 1700 ° C. and a nitrogen pressure of 2000 atm for 1 hour after the above GPS firing.
【００３１】また、試料Ｎo.３６〜３９については、平
均粒径３μｍ、酸素量１．１重量％の珪素粉末を用い
て、窒化珪素粉末の一部に代えて窒化後の比率が表１の
（ ）内の比率となる量を配合した。そして、窒素中、
１３００℃で１０時間窒化処理した。窒化後の焼結体中
には珪素が残存していないことをＸ線回折測定によって
確認した。その後、窒化体を表１の焼成条件で焼成し
た。なお、表１中のＳｉ量は窒化後の重量比率である。Samples Nos. 36 to 39 used silicon powder having an average particle diameter of 3 μm and an oxygen content of 1.1% by weight. The amount of the ratio in () was blended. And in nitrogen,
A nitriding treatment was performed at 1300 ° C. for 10 hours. It was confirmed by X-ray diffraction measurement that no silicon remained in the sintered body after nitriding. Thereafter, the nitride was fired under the firing conditions shown in Table 1. In addition, the amount of Si in Table 1 is a weight ratio after nitriding.
【００３２】得られた各焼結体に対してアルキメデス法
による比重から対理論密度比を算出するとともに、３×
４×４０mmのテストピース形状に切断研磨し、ＪＩＳ−
Ｒ−１６０１に基づき室温および１５００℃での４点曲
げ抗折強度試験を実施し、１０個の試験結果の平均値を
表２に示した。また、Ｘ線回折測定により焼結体の粒界
相の結晶を同定した。なお、表１中の不純物的酸素量
は、焼結体を粉砕し化学分析によって全酸素量を求め、
添加した周期律表第３ａ族元素酸化物中の酸素量を除い
た酸素量をＳｉＯ2 換算したものである。さらに抗折試
験片をＪＩＳ−Ｒ−１６０１の４点曲げ試験と同様に支
持し、４５０ＭＰａの負荷を印加し１５００℃で最高２
００時間保持し、破壊に至るまでの時間を測定した。ま
た、破壊靱性値の測定はＩＭ法にて測定した。For each of the obtained sintered bodies, a theoretical density ratio was calculated from the specific gravity by the Archimedes method, and 3 ×
Cut and polished into a 4 x 40 mm test piece shape, JIS-
Based on R-1601, a four-point bending strength test was performed at room temperature and 1500 ° C., and the average of the results of the ten tests is shown in Table 2. Further, the crystal of the grain boundary phase of the sintered body was identified by X-ray diffraction measurement. In addition, the amount of impurity oxygen in Table 1 is obtained by pulverizing a sintered body and obtaining the total oxygen amount by chemical analysis.
The oxygen content excluding the oxygen content in the added Group 3a element oxide of the periodic table is converted into SiO 2 . Further, the bending test piece was supported in the same manner as in the four-point bending test of JIS-R-1601, and a load of 450 MPa was applied, and a maximum of 2
The sample was held for 00 hours, and the time until destruction was measured. The fracture toughness was measured by the IM method.
【００３３】[0033]
【表１】 [Table 1]
【００３４】[0034]
【表２】 [Table 2]
【００３５】表１、表２の結果から明らかなように、本
発明の試料は、いずれも室温強度９００ＭＰａ以上、１
５００℃強度６００ＭＰａ以上、靱性７．５ＭＰａ・ｍ
1/2以上、耐クリープ性２００時間以上の優れた高温特
性を示した。As is clear from the results shown in Tables 1 and 2, all of the samples of the present invention had a room temperature strength of 900 MPa or more.
500 ° C strength of 600 MPa or more, toughness of 7.5 MPa · m
Excellent high-temperature properties of 1/2 or more and 200 hours or more of creep resistance were exhibited.
【００３６】[0036]
【発明の効果】以上詳述したように、本発明の窒化珪素
複合焼結体は、特定の硬質粒子を配合するとともに、焼
結助剤としてＬｕ化合物を用いることにより、室温から
１５００℃の高い温度において、優れた高温強度と靱性
とともに、耐クリープ特性に優れるものであり、これに
より、自動車用部品やガスタービンエンジン用部品とし
てその耐久性を大幅に向上させることができる。As described in detail above, the silicon nitride composite sintered body of the present invention is prepared by mixing specific hard particles and using a Lu compound as a sintering aid to increase the temperature from room temperature to 1500 ° C. At high temperatures, it has excellent high-temperature strength and toughness, as well as excellent creep resistance, and as a result, its durability can be significantly improved as a component for an automobile or a component for a gas turbine engine.
Claims (4)
化物換算で０．５〜１０モル％と、残部が不純物的酸素
からなる窒化珪素成分と、該窒化珪素成分１００重量部
に対して、Ｔａ、Ｎｂ、Ｍｏ、Ｗの珪化物及びＳｉＣの
中から選ばれる少なくとも１種の硬質粒子成分を０．５
〜２５重量部の割合で分散含有してなる複合焼結体であ
って、前記窒化珪素が平均粒径５μｍ以下、平均アスペ
クト比が５以上の結晶粒子として、前記硬質粒子が平均
粒径１〜５μｍの結晶粒子として存在するとともに、前
記不純物的酸素及びＬｕを含む周期律表第３ａ族元素が
主として窒化珪素結晶粒子及び硬質粒子の粒界にアパタ
イト、ＹＡＭ及び、ワラストナイトからなる群より選ば
れた少なくとも１種以上の結晶相として存在することを
特徴とする窒化珪素質複合焼結体。1. A silicon nitride component comprising 70 to 99 mol% of silicon nitride, 0.5 to 10 mol% of Lu in terms of oxide, and a silicon nitride component comprising the remainder of impurity oxygen and 100 parts by weight of the silicon nitride component. On the other hand, at least one hard particle component selected from silicides of Ta, Nb, Mo, and W and SiC is added in an amount of 0.5%.
A composite sintered body that is dispersed and contained at a ratio of ２５25 parts by weight, wherein the silicon nitride has a mean particle size of 5 μm or less and an average aspect ratio of 5 or more, and the hard particles have an average particle size of 1 to 5. The group 3a element of the periodic table containing the impurity oxygen and Lu, which is present as 5 μm crystal grains, is mainly selected from the group consisting of apatite, YAM, and wollastonite at the grain boundaries of silicon nitride crystal grains and hard grains. A silicon nitride-based composite sintered body characterized by being present as at least one or more crystal phases.
素のＳｉＯ2 換算量の前記周期律表第３ａ族元素の酸化
物換算量に対するモル比が２未満であることを特徴とす
る請求項１記載の窒化珪素質複合焼結体。2. The silicon nitride component according to claim 1, wherein the molar ratio of the amount of the impurity oxygen in terms of SiO 2 to the amount in terms of the oxide of a Group 3a element of the periodic table is less than 2. Silicon nitride composite sintered body.
化物換算で０．５〜１０モル％と、残部が不純物的酸素
からなり、前記不純物的酸素のＳｉＯ2 換算量の前記Ｌ
ｕを含む周期律表第３ａ族元素の酸化物換算量に対する
モル比が２未満の窒化珪素成分と、該窒化珪素成分１０
０重量部に対して、平均粒径が１〜５μｍのＴａ、Ｎ
ｂ、Ｍｏ、Ｗの珪化物及びＳｉＣの群から選ばれる少な
くとも１種の硬質粒子成分を０．５〜２５重量部の割合
で分散含有してなる成形体を、窒素を含む非酸化性雰囲
気中で１６００〜１８００℃で保持して窒化珪素結晶を
柱状化させた後、次いで１８００℃より高い温度で焼結
させることを特徴とする窒化珪素質複合焼結体の製造方
法。3. A silicon nitride 70 to 99 mol%, and 0.5 to 10 mol% Lu in terms of oxide, the balance being impurities oxygen, wherein the SiO 2 equivalent amount of the impurity oxygen L
a silicon nitride component having a molar ratio of less than 2 to the oxide equivalent of a Group 3a element of the periodic table containing u,
Ta, N having an average particle size of 1 to 5 μm with respect to 0 parts by weight.
b, Mo, W A molded body containing at least one hard particle component selected from the group consisting of silicides of Si and SiC at a ratio of 0.5 to 25 parts by weight in a non-oxidizing atmosphere containing nitrogen. The method of manufacturing a silicon nitride-based composite sintered body characterized in that, after holding at 1600 to 1800 ° C. to form the silicon nitride crystal into a column, then sintering at a temperature higher than 1800 ° C.
算で７０〜９９モル％と、Ｌｕを酸化物換算で０. ５〜
１０モル％と、残部が不純物的酸素からなり、前記不純
物的酸素のＳｉＯ2 換算量の前記Ｌｕを含む周期律表第
３ａ族元素の酸化物換算量に対するモル比が２未満の窒
化珪素成分と、該窒化珪素成分１００重量部に対して、
平均粒径が１〜５μｍのＴａ、Ｎｂ、Ｍｏ、Ｗの珪化物
及びＳｉＣの群から選ばれる少なくとも１種の硬質粒子
成分を０．５〜２５重量部の割合で分散含有してなる成
形体を、８００〜１５００℃の窒素含有雰囲気中で熱処
理して前記珪素を窒化した後、さらに窒素を含む非酸化
性雰囲気中で１６００℃〜１８００℃で保持して窒化珪
素結晶を柱状化させた後、次いで１８００℃よりも高い
温度で焼結させることを特徴とする窒化珪素質複合焼結
体の製造方法。4. Silicon or silicon and silicon nitride in an amount of 70 to 99 mol% in terms of nitride, and Lu in an amount of 0.5 to 0.5% in terms of oxide.
A silicon nitride component comprising 10 mol% and the balance being impurity oxygen, wherein the molar ratio of the impurity oxygen in terms of SiO 2 to the oxide equivalent of the Group 3a element of the periodic table containing Lu is less than 2; With respect to 100 parts by weight of the silicon nitride component,
Molded product comprising at least one hard particle component selected from the group consisting of silicides of Ta, Nb, Mo, W having an average particle diameter of 1 to 5 μm and SiC in a proportion of 0.5 to 25 parts by weight. Is heat-treated in a nitrogen-containing atmosphere at 800 to 1500 ° C. to nitride the silicon, and is further maintained at 1600 to 1800 ° C. in a non-oxidizing atmosphere containing nitrogen to form a columnar silicon nitride crystal. And then sintering at a temperature higher than 1800 ° C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9018089A JPH10212167A (en) | 1997-01-31 | 1997-01-31 | Silicon nitride-base composite sintered compact and its production |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9018089A JPH10212167A (en) | 1997-01-31 | 1997-01-31 | Silicon nitride-base composite sintered compact and its production |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH10212167A true JPH10212167A (en) | 1998-08-11 |
Family
ID=11961924
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9018089A Pending JPH10212167A (en) | 1997-01-31 | 1997-01-31 | Silicon nitride-base composite sintered compact and its production |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH10212167A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000247748A (en) * | 1999-02-22 | 2000-09-12 | Kyocera Corp | High-toughness silicon nitride-based sintered compact |
| JP2004051451A (en) * | 2002-07-23 | 2004-02-19 | National Institute Of Advanced Industrial & Technology | Anisotropic porous silicon nitride-based ceramic and method for sintering/forming/machining the same |
| WO2005019133A1 (en) * | 2003-08-26 | 2005-03-03 | Kyocera Corporation | Silicon nitride based sintered material and method for producing the same, and molten-metal-resistant member and wear-resistant member using the same |
-
1997
- 1997-01-31 JP JP9018089A patent/JPH10212167A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000247748A (en) * | 1999-02-22 | 2000-09-12 | Kyocera Corp | High-toughness silicon nitride-based sintered compact |
| JP2004051451A (en) * | 2002-07-23 | 2004-02-19 | National Institute Of Advanced Industrial & Technology | Anisotropic porous silicon nitride-based ceramic and method for sintering/forming/machining the same |
| WO2005019133A1 (en) * | 2003-08-26 | 2005-03-03 | Kyocera Corporation | Silicon nitride based sintered material and method for producing the same, and molten-metal-resistant member and wear-resistant member using the same |
| JPWO2005019133A1 (en) * | 2003-08-26 | 2007-11-01 | 京セラ株式会社 | Silicon nitride-based sintered body, method for producing the same, member for molten metal using the same, and member for wear resistance |
| KR100855226B1 (en) * | 2003-08-26 | 2008-08-29 | 쿄세라 코포레이션 | Silicon nitride based sintered material and method for producing the same, and molten-metal-resistant member and wear-resistant member using the same |
| US7642209B2 (en) | 2003-08-26 | 2010-01-05 | Kyocera Corporation | Silicon nitride sintered material and method for manufacturing |
| JP4717635B2 (en) * | 2003-08-26 | 2011-07-06 | 京セラ株式会社 | Silicon nitride-based sintered body, method for producing the same, member for molten metal using the same, and member for wear resistance |
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