JPH05254950A - High toughness ceramic member - Google Patents
High toughness ceramic memberInfo
- Publication number
- JPH05254950A JPH05254950A JP4054987A JP5498792A JPH05254950A JP H05254950 A JPH05254950 A JP H05254950A JP 4054987 A JP4054987 A JP 4054987A JP 5498792 A JP5498792 A JP 5498792A JP H05254950 A JPH05254950 A JP H05254950A
- Authority
- JP
- Japan
- Prior art keywords
- pores
- substrate
- porosity
- ceramic member
- surface layer
- 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
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/007—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof characterised by the pore distribution, e.g. inhomogeneous distribution of pores
- C04B38/0077—Materials with a non-porous skin
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、機械的性質、特に破壊
特性に優れ、かつ低比重のセラミックス焼結体の構造に
関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a ceramic sintered body which has excellent mechanical properties, particularly fracture properties, and has a low specific gravity.
【０００２】[0002]
【従来の技術】窒化ケイ素をはじめとする構造用セラミ
ックスは、破壊強度が高く、耐食性、耐摩耗性および耐
熱性も良いといった他のセラミックスにない優れた特性
をそなえている。しかしながら、セラミックス特有の弱
点である脆いという性質も持ち合わせている。このた
め、機械的性質の向上、特に破壊特性を改善することが
当該分野での課題となっている。2. Description of the Related Art Structural ceramics such as silicon nitride have high breaking strength and excellent characteristics such as corrosion resistance, wear resistance and heat resistance which other ceramics do not have. However, it also has the property of being brittle, which is a weak point peculiar to ceramics. Therefore, improvement of mechanical properties, and in particular, improvement of fracture characteristics has been a problem in this field.
【０００３】脆いということは、破壊靭性すなわち破壊
に対する抵抗力が小さいということを意味し、近年、複
合化等による破壊靭性向上のための研究が進められてい
る。構造用セラミックスの破壊靭性を向上させるために
は、破壊靭性値ＫICおよび破壊エネルギーを増大させる
ことが必要である。破壊靭性値ＫICは、巨視的亀裂の進
展開始時の抵抗力として作用し、一方、破壊エネルギー
はいったん進展した亀裂を阻止するための抵抗力として
作用する。たとえば、炭化ケイ素ウイスカー（短繊維）
やファイバー（長繊維）などのセラミックス繊維を複合
して構造用セラミックスを強化することにより、前述の
抵抗力を生じさせ、カタストロフィックな破壊を阻止す
ることができる。The brittleness means that the fracture toughness, that is, the resistance to fracture is small, and in recent years, research for improving fracture toughness by compounding has been advanced. In order to improve the fracture toughness of structural ceramics, it is necessary to increase the fracture toughness value K IC and the fracture energy. The fracture toughness value K IC acts as a resistance force at the start of the growth of a macroscopic crack, while the fracture energy acts as a resistance force to prevent a crack that has once grown. For example, silicon carbide whiskers (short fibers)
By reinforcing the structural ceramics by compounding ceramic fibers such as or fibers (long fibers), it is possible to generate the above-described resistance force and prevent catastrophic destruction.
【０００４】従来、これら複合構造用セラミックスの多
くは、緻密な構造にすることによって、強度および靭性
値を向上させてきた。それらは強度、破壊靭性値におい
て、ある程度の向上はみられたが、破壊挙動に関して
は、十分な改善がみられていない。すなわち、緻密な構
造の複合材においては、その内部に亀裂が成長し始める
と、構造が緻密であるゆえに亀裂は直線的に成長し、カ
タストロフィックな破壊につながりやすい。したがっ
て、セラミックス繊維で複合強化した構造材の場合で
も、脆さという点においては、いまだ十分な解決がなさ
れていないのが現状である。Conventionally, many of these ceramics for composite structures have been improved in strength and toughness by forming a dense structure. Although they showed some improvement in strength and fracture toughness, they did not show sufficient improvement in fracture behavior. That is, in a composite material having a dense structure, when a crack begins to grow inside the composite material, the crack grows linearly due to the dense structure, which easily leads to catastrophic failure. Therefore, even in the case of a structural material compositely reinforced with ceramics fibers, the brittleness is not yet sufficiently solved.
【０００５】繊維強化の最大の目的は、部材に加えられ
た荷重を繊維が担う、いわゆる繊維の引き抜き効果によ
り、靭性を向上させるということにある。このために
は、母材と繊維との間の接合状態が大きな要素になって
いる。両者が強固に接合していれば、母材の破壊と同時
に繊維の破断が起きてしまい、また、両者の接合が過度
に弱い場合には、繊維の引き抜きが容易に生じてしま
う。すなわち、いずれの場合も繊維強化の効果を十分に
発揮することができない。理想的には、母材の破壊およ
び母材−繊維間の剥離、繊維の引き抜き、繊維の破断の
順に破壊が進行することが好ましい。しかしながら、適
度な接合界面をもつように繊維をコーティングする必要
があるなど、母材と繊維との接合状態を制御する上で、
数々の問題があった。The most important purpose of fiber reinforcement is to improve the toughness by the so-called fiber pull-out effect in which the fiber bears the load applied to the member. For this purpose, the bonding state between the base material and the fibers is a major factor. If the two are firmly bonded, the fiber is broken at the same time as the base material is broken, and if the two are too weakly bonded, the fiber is easily pulled out. That is, in any case, the effect of fiber reinforcement cannot be sufficiently exhibited. Ideally, the breakage proceeds in the order of breakage of the base material, separation between the base material and the fibers, drawing of the fibers, and breakage of the fibers. However, in controlling the bonding state between the base material and the fiber, such as coating the fiber so that it has an appropriate bonding interface,
There were a number of problems.
【０００６】ところで、実際の構造材においては、製造
中に若干の潜在亀裂が存在していても、瞬時に破壊に至
らない、いわゆる信頼性の高い材料への要求が高く、多
少強度の低下をともなっても、容易に破壊に至らず、壊
れにくい材料に対する適用範囲は広いものである。By the way, in actual structural materials, even if some latent cracks are present during manufacturing, there is a high demand for a so-called highly reliable material that does not cause instantaneous destruction, and the strength is somewhat lowered. Therefore, the scope of application is wide for materials that do not easily break and are hard to break.
【０００７】[0007]
【発明が解決しようとする課題】部材中に発生した亀裂
が、進展を開始すると同時に、部材の即時破断がもたら
されるというセラミックス特有の脆さが、構造用材料を
製造する際に問題となっていた。したがって本発明は、
上述の問題点を解決し、破壊特性に優れ、信頼性が高い
構造用セラミックスを提供することを課題とする。The fragility peculiar to ceramics, in which a crack generated in a member starts to propagate at the same time that an immediate fracture of the member is caused, has been a problem in manufacturing a structural material. It was Therefore, the present invention
It is an object of the present invention to solve the above-mentioned problems and provide a structural ceramic having excellent fracture characteristics and high reliability.
【０００８】[0008]
【課題を解決するための手段】上記課題を解決するため
に、本発明は、酸化物系または非酸化物系セラミックス
を母材とし、前記母材より破断歪が大きいセラミックス
繊維を強化材として５０重量％まで含み得るセラミック
ス材料の焼結体からなり、前記焼結体は、独立気孔を内
包する多孔性基体と、この基体の１の主表面に一体的に
焼結された緻密な表層部とを有し、前記基体は、最大気
孔率を有する最多孔性部を、前記表層部から離間して、
かつ前記表層部と実質的に平行に延在して有し、さらに
前記基体内において、前記１の主表面から前記最多孔性
部に向かって、気孔率が漸増していることを特徴とする
高靭性セラミックス部材を提供する。In order to solve the above problems, the present invention uses an oxide-based or non-oxide-based ceramic as a base material and a ceramic fiber having a breaking strain larger than that of the base material as a reinforcing material. The sintered body is composed of a sintered body of a ceramic material which can contain up to 1% by weight, and the sintered body has a porous base body containing independent pores, and a dense surface layer portion integrally sintered on one main surface of the base body. And the substrate has the most porous portion having the maximum porosity, separated from the surface layer portion,
And extending substantially parallel to the surface layer portion, and further, in the substrate, the porosity gradually increases from the main surface of 1 toward the most porous portion. A high toughness ceramic member is provided.
【０００９】本発明の好ましい態様においては、前記部
材の基体内部に存在する気孔について、部材の厚さ方向
に沿った径と、それに直交する方向の径との比は０．１
〜１０であって、前記基体の最多孔性部における気孔率
は、４０％以下である。In a preferred aspect of the present invention, with respect to the pores existing inside the base of the member, the ratio between the diameter along the thickness direction of the member and the diameter in the direction orthogonal thereto is 0.1.
10 to 10, and the porosity in the most porous portion of the substrate is 40% or less.
【００１０】[0010]
【作用】一般に、セラミックスの破壊は、部材の１カ所
あるいは数カ所に生じる応力集中に起因する。集中した
応力が破壊応力に達した結果、カタストロフィックな破
壊へと進展していく。したがって、この応力集中をでき
る限り緩和し、かつ万が一亀裂が発生しても、安定的な
破壊挙動を起こさせることが、材料の信頼性を高めるた
めに必要である。In general, the destruction of ceramics is due to the stress concentration occurring at one place or several places of the member. As a result of the concentrated stress reaching the fracture stress, it progresses to catastrophic fracture. Therefore, in order to improve the reliability of the material, it is necessary to alleviate this stress concentration as much as possible and to cause stable fracture behavior even if a crack should occur.
【００１１】本発明によれば、セラミックス部材の基体
に気孔を存在させることにより、亀裂の進展を一時的に
阻止することができる。金属材料の場合には、局所的な
応力の集中を避けるため、あらかじめ円孔等を設けて応
力の集中を緩和することが行なわれているが、本発明に
おいては、組織中に気孔を存在させることにより、同様
に応力集中の緩和を図るものである。すなわち、気孔に
達した亀裂はその先端の鋭さを失うため、さらに亀裂を
進展させるには、破壊エネルギーの増大が必要になる。
また、繊維で複合強化したセラミックス部材の内部に気
孔を存在させた場合は、上述の作用に加えて、母材−繊
維間の剥離が容易になり、繊維の引き抜き効果が生じや
すくなる。このため、母材と繊維との好ましい接合状態
が得られ、理想的なプロセスで破壊が生じる。すなわ
ち、この繊維と気孔との相乗効果により、内部に亀裂が
生じた際も、瞬時にカタストロフィックな破壊が生じな
いセラミックス部材を提供することできる。さらに、部
材の表層部を緻密化したことにより、外力に対する強度
は、完全に緻密な部材とほぼ同等の強度を保つことがで
きる。According to the present invention, the presence of pores in the base body of the ceramic member makes it possible to temporarily prevent the development of cracks. In the case of a metal material, in order to avoid local concentration of stress, it has been attempted to provide a circular hole or the like in advance to reduce the concentration of stress. In the present invention, however, pores are allowed to exist in the tissue. By doing so, the stress concentration is similarly relaxed. That is, since the crack reaching the pore loses the sharpness of its tip, it is necessary to increase the fracture energy to further propagate the crack.
Further, when the pores are present inside the ceramic member composite-reinforced with fibers, in addition to the above-described action, separation between the base material and the fibers is facilitated, and the effect of pulling out the fibers is likely to occur. For this reason, a preferable bonding state between the base material and the fiber is obtained, and the ideal process breaks. That is, by the synergistic effect of the fibers and the pores, it is possible to provide a ceramic member that does not cause catastrophic destruction instantly even when a crack is generated inside. Further, by densifying the surface layer portion of the member, the strength against external force can be kept substantially the same as that of the completely dense member.
【００１２】[0012]
【実施例】以下、図面を参照して本発明の一態様を説明
する。図１に本発明の高靭性セラミックス部材の断面構
造を示す。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross-sectional structure of the high toughness ceramic member of the present invention.
【００１３】本発明の高靭性セラミックス部材１１は、
非酸化物系セラミックス、例えば、窒化ケイ素からな
り、独立気孔を内包する多孔性基体１７と、前記基体１
７の２の主表面に一体的に焼結された、緻密な構造の表
層部１２および１３とを有する。ここで、主表面とは、
部材を使用する際に、周囲の雰囲気、外力に曝される側
の面をいう。The high toughness ceramic member 11 of the present invention is
A porous substrate 17 made of non-oxide ceramics, for example, silicon nitride, and containing independent pores;
No. 7 of FIG. 7 has surface layers 12 and 13 having a dense structure integrally sintered on the two main surfaces thereof. Here, the main surface is
When using a member, it means the surface on the side exposed to the ambient atmosphere and external force.
【００１４】表層部１２および１３において、その密度
は、実質的に理論密度に等しく、十分に緻密化されてい
る。したがって、基体１７に気孔を内包させることによ
って生じる部材１１の強度低下を抑制し、外力に対して
強度を保つことができる。すなわち、本部材の強度は、
表層部が存在することにより、完全に緻密な構造にした
部材の８０％程度に保つことができる。また、各表層部
の厚さは、いずれも部材１１の５％程度である。In the surface layer portions 12 and 13, the density is substantially equal to the theoretical density and is sufficiently densified. Therefore, it is possible to suppress the strength reduction of the member 11 caused by the inclusion of the pores in the base body 17 and to maintain the strength against an external force. That is, the strength of this member is
Due to the presence of the surface layer portion, it is possible to keep about 80% of the member having a completely dense structure. The thickness of each surface layer is about 5% of the member 11.
【００１５】基体１７中に存在する気孔は、図３に示す
ように、全体的に曲率を有した形状であることが好まし
い。図３に示す気孔において、ａ0 は、部材の厚さ方向
に沿った径を表わし、ａ1 は、それに直交する方向の径
を表わす。気孔のアスペクト比（ａ0 ／ａ1 ）は、０．
１〜１０の範囲内であることが好ましい。また、気孔の
大きさは、好ましくは母材の粒径大程度である。It is preferable that the pores existing in the base 17 have a shape having a general curvature as shown in FIG. In the pores shown in FIG. 3, a 0 represents the diameter along the thickness direction of the member, and a 1 represents the diameter in the direction orthogonal thereto. The aspect ratio (a 0 / a 1 ) of the pores is 0.
It is preferably in the range of 1-10. The size of the pores is preferably about the same as the particle size of the base material.
【００１６】基体１７は、気孔率が漸増しており、互い
に等しい厚さを有する、気孔率遷移部１４および１５
が、気孔率が最大である最多孔性部１６を介して一体と
なった構造である。The substrate 17 has gradually increasing porosity and has the same thickness as each other.
However, the structure is integrated through the most porous portion 16 having the maximum porosity.
【００１７】最多孔性部１６は、表層部１２および１３
と平行に延在している。本最多孔性部の気孔率は、４０
％程度である。気孔が亀裂の進展を妨げる等の機能を果
たすため、および、後述するウイスカーの引き抜き効果
を発生させやすくするためには、この程度の気孔率が必
要である。しかし、気孔率が４０％を越えると、強度低
下が著しくなり、構造用材料として実用に適さない。The most porous portion 16 is the surface layer portions 12 and 13.
It extends in parallel with. The porosity of the most porous portion is 40.
%. The porosity of this level is necessary in order for the pores to function such as preventing the development of cracks and for facilitating the whisker extraction effect described later. However, when the porosity exceeds 40%, the strength is significantly reduced, and it is not suitable for practical use as a structural material.
【００１８】気孔率遷移部１４および１５は、気孔率が
表層部から最多孔性部に向かって、漸増している構造で
ある。気孔率遷移部１４および１５において、その最多
孔性部との界面における気孔率は、実質的に最多孔性部
における気孔率と等しい。The porosity transition portions 14 and 15 have a structure in which the porosity gradually increases from the surface layer portion toward the most porous portion. In the porosity transition parts 14 and 15, the porosity at the interface with the most porous part is substantially equal to the porosity in the most porous part.
【００１９】基体１７における気孔の作用を図４に示
す。図４（ａ）に、気孔３２を有する部材中に亀裂３１
が発生した状態を示す。亀裂３１が進展して、その鋭い
先端が、気孔３２に接することにより、丸みを帯びるこ
とになる（図４（ｂ））。すなわち、亀裂３１の先端の
鈍化が引き起こされ、さらなる亀裂の進展には、応力の
増加が必要となる。このように、気孔の存在により、亀
裂の進展は一時的に阻止され、カタストロフィックな破
壊が防止される。ただし、この場合、亀裂３１の先端半
径は、気孔３２のそれに比べて十分小さく、限りなく０
に近いものとする。また、気孔率遷移部１４および１５
において、気孔３２が漸増していることにより、亀裂３
１の偏向が促進される。例えば、部材１１において一方
の表層部１２から亀裂が発生した場合には、亀裂は中央
の最多孔性部１６に、容易に到達することができない。
このため、部材の破壊に必要なエネルギーが増大するこ
とにもなる。The function of the pores in the substrate 17 is shown in FIG. As shown in FIG. 4A, a crack 31 is formed in a member having pores 32.
Indicates a state in which is generated. The crack 31 progresses, and its sharp tip comes into contact with the pore 32 to be rounded (FIG. 4B). That is, the tip of the crack 31 is blunted, and the stress needs to be increased in order to further propagate the crack. In this way, the presence of the pores temporarily prevents the development of cracks and prevents catastrophic destruction. However, in this case, the tip radius of the crack 31 is sufficiently smaller than that of the pores 32, and is infinitely zero.
Shall be close to. In addition, the porosity transition portions 14 and 15
At the crack 3 due to the gradually increasing pores 32.
The deflection of 1 is promoted. For example, when a crack is generated from one surface layer portion 12 of the member 11, the crack cannot easily reach the central most porous portion 16.
Therefore, the energy required for breaking the member also increases.
【００２０】さらに、本発明の高靭性セラミックス部材
の別の態様を、図２に示す。図２において、部材２１
は、基体２２の１の主表面に緻密な構造からなる表層部
１２を有する。また、前記主表面に対向する表面部（こ
の表面は、使用時に周囲雰囲気に曝されないものであ
る）が、最多孔性部１６となっているものである。部材
２１における表層部１２の密度および最多孔性部１６の
気孔率は、図１に示す部材１１の場合と同様である。た
だし、部材２１は、使用の際に１の表面のみが周囲の雰
囲気、外力に曝されるため、表層部１２の厚さは、部材
２１の厚さの５％程度とする。前記表層部１２と前記最
多孔性部１６との間には、気孔率が漸増する気孔率遷移
部１４が、同様に存在する。Further, another embodiment of the high toughness ceramic member of the present invention is shown in FIG. In FIG. 2, the member 21
Has a surface layer portion 12 having a dense structure on one main surface of the substrate 22. In addition, the surface portion facing the main surface (this surface is not exposed to the ambient atmosphere during use) is the most porous portion 16. The density of the surface layer portion 12 and the porosity of the most porous portion 16 of the member 21 are the same as those of the member 11 shown in FIG. However, since only the surface of the member 21 is exposed to the ambient atmosphere and external force when used, the thickness of the surface layer portion 12 is set to about 5% of the thickness of the member 21. Between the surface layer portion 12 and the most porous portion 16, there is also a porosity transition portion 14 in which the porosity gradually increases.
【００２１】本発明のセラミックス部材は、基体を多孔
質にしたことにより、破壊強度が、若干低下するが、軽
量化をはかることができる。完全に緻密化された従来の
セラミックス部材と比較すると、本部材１１の破壊強度
は８０％程度となり、その質量は７５％程度とすること
ができ、実用上問題ない。In the ceramic member of the present invention, the breaking strength is slightly lowered by making the substrate porous, but the weight can be reduced. Compared to a completely densified conventional ceramic member, the breaking strength of the member 11 is about 80%, and its mass can be about 75%, which is not a practical problem.
【００２２】なお、本発明のセラミックス部材は、窒化
ケイ素のような非酸化物系セラミックスをマトリックス
として、炭化ケイ素ウイスカーのようなセラミックス繊
維を分散させた構造とすることもできる。部材に引張り
応力が加えられると、部材は変形し、その歪が破断歪に
至った場合に、部材は破断する。例えば、炭化ケイ素ウ
イスカーの破断歪は、ホットプレスされた窒化ケイ素セ
ラミックスの破断歪に比較して、数倍程度大きい。この
ため、複合強化の効果を十分に発揮させることができ
る。複合させるウイスカーのアスペクト比は、１０〜１
００であることが好ましい。また、前記部材１１におけ
るウイスカーの含有率は、５０重量％以下が好ましい。
５０重量％を越えると、非酸化物である炭化ケイ素の影
響が大きくなり、母材である窒化ケイ素の高温での特性
を損なうことになる。The ceramic member of the present invention may have a structure in which non-oxide ceramics such as silicon nitride is used as a matrix and ceramic fibers such as silicon carbide whiskers are dispersed. When a tensile stress is applied to the member, the member is deformed, and when the strain reaches a breaking strain, the member breaks. For example, the breaking strain of silicon carbide whiskers is several times larger than the breaking strain of hot-pressed silicon nitride ceramics. Therefore, the effect of composite strengthening can be sufficiently exerted. The aspect ratio of the combined whiskers is 10 to 1
It is preferably 00. The content of whiskers in the member 11 is preferably 50% by weight or less.
If it exceeds 50% by weight, the effect of non-oxide silicon carbide becomes large and the characteristics of the base material silicon nitride at high temperature are impaired.
【００２３】ウイスカーで強化した複合材における、気
孔とウイスカーとの作用を図５に示す。気孔４１を横切
るウイスカー４２付近においては、ウイスカーに直角な
方向から亀裂が進展する現象のほか、図５（ａ）に示す
ようにウイスカー４２の長さ方向に応力σが加えられる
現象も生じ得る。この場合、図５（ｂ）に示すように、
応力集中によって気孔４１とウイスカー４２との界面に
剥離点４３を生じる。この結果、ウイスカーの引き抜き
効果が発現しやすくなり、母材とウイスカーとが強固に
接合している場合より、極めて大きなエネルギーの散逸
が生じる。したがって、気孔４１が存在することによ
り、ウイスカー４２に応力σを伝えやすくし、材料の高
靭化をさらに図ることができる。The effect of pores and whiskers in a whisker reinforced composite is shown in FIG. In the vicinity of the whiskers 42 that cross the pores 41, in addition to the phenomenon that cracks propagate from the direction perpendicular to the whiskers, a phenomenon that stress σ is applied in the length direction of the whiskers 42 may occur as shown in FIG. 5A. In this case, as shown in FIG.
The stress concentration causes a separation point 43 at the interface between the pores 41 and the whiskers 42. As a result, the effect of pulling out the whiskers is likely to be exhibited, and an extremely large amount of energy is dissipated as compared with the case where the base material and the whiskers are firmly joined. Therefore, the presence of the pores 41 makes it easier to transmit the stress σ to the whiskers 42, and the toughness of the material can be further enhanced.
【００２４】本発明に係る部材を製造するに当たり、炭
化ケイ素ウイスカーで複合強化する場合の原料粉末は、
窒化ケイ素粉末に任意の含有量の炭化ケイ素ウイスカー
をボールミルで均一に混合し、調製した混合粉末を使用
する。In producing the member according to the present invention, the raw material powder for composite strengthening with silicon carbide whiskers is
A silicon carbide whisker having an arbitrary content is uniformly mixed with a silicon nitride powder by a ball mill, and the prepared mixed powder is used.
【００２５】また、基体中に気孔を発生させる方法とし
ては、原料粉末を任意形状のモールド中で成形した後、
１００℃程度の温度差を、部材の厚さ方向に与えて焼結
させる方法、または、ウイスカーの添加量を変える方法
をあげることができる。As a method for generating pores in the substrate, after forming the raw material powder in a mold of an arbitrary shape,
A method of applying a temperature difference of about 100 ° C. in the thickness direction of the member for sintering, or a method of changing the addition amount of whiskers can be mentioned.
【００２６】本発明に係る高靭性セラミックス部材につ
いての変形挙動を調べた。前述の焼結体を４×３×４０
の試験片に加工し、ＳＥＮＢ法による３点曲げ破壊靭性
試験を行なった。その結果を、荷重と荷重点の変位（変
位曲線）について、図６に曲線ａで示す。比較例とし
て、全体を緻密化した、従来の炭化ケイ素ウイスカー
（２０重量％）／窒化ケイ素材料の試験結果を、併せて
曲線ｂで示す。図６より、本発明のセラミックス部材
は、全体を緻密化した従来のセラミックス部材と比較し
て、破壊強度は落ちるものの、最大荷重後もすぐにはカ
タストロフィックな破壊を引き起こさないことがわか
る。すなわち、本発明のセラミックス部材は、安定した
破壊挙動を示し、破壊エネルギーが大きい。このこと
は、本部材が、亀裂に対して鈍感であることを意味して
おり、母材自体に潜在的な亀裂があったとしても、それ
が直ちに破壊をもたらすものではなく、信頼性の高い材
料であるといえる。The deformation behavior of the high toughness ceramic member according to the present invention was investigated. 4 x 3 x 40 of the above sintered body
Was subjected to a 3-point bending fracture toughness test by the SENB method. The result is shown by the curve a in FIG. 6 for the load and the displacement of the load point (displacement curve). As a comparative example, the test result of a conventional silicon carbide whisker (20% by weight) / silicon nitride material, which is densified as a whole, is also shown by a curve b. It can be seen from FIG. 6 that the ceramic member of the present invention has a lower fracture strength than the conventional ceramic member which is densified as a whole, but does not cause catastrophic fracture immediately after the maximum load. That is, the ceramic member of the present invention exhibits stable fracture behavior and has large fracture energy. This means that this member is insensitive to cracks, and even if there is a potential crack in the base material itself, it does not cause immediate fracture and is highly reliable. It can be said that it is a material.
【００２７】[0027]
【発明の効果】以上詳述したように、本発明によると、
部材の基体中に独立した気孔を包含させたことにより、
破壊靭性値を増大させた構造用セラミックスを提供する
ことができる。さらに、ウイスカーで強化した複合材に
おいては、気孔とウイスカーとの相乗効果により、高靭
化が一層図られる。なお、部材の表層部を緻密にしたこ
とにより、外力に対する強度は、従来の８０％程度に保
たれる。また、２５％程度の軽量化を図ることもでき
る。As described in detail above, according to the present invention,
By including independent pores in the substrate of the member,
A structural ceramic having an increased fracture toughness value can be provided. Further, in the composite material reinforced with whiskers, the toughness is further enhanced by the synergistic effect of pores and whiskers. By making the surface layer of the member dense, the strength against external force is maintained at about 80% of the conventional level. It is also possible to reduce the weight by about 25%.
【図１】本発明に係る高靭性セラミックス部材の一実施
例の断面構造を示す図。FIG. 1 is a diagram showing a cross-sectional structure of one embodiment of a high toughness ceramic member according to the present invention.
【図２】本発明に係る高靭性セラミックス部材の他の実
施例の断面構造を示す図。FIG. 2 is a diagram showing a cross-sectional structure of another embodiment of the high toughness ceramic member according to the present invention.
【図３】本発明に係る高靭性セラミックス部材の基体内
部の気孔の形状を示す図。FIG. 3 is a view showing the shape of pores inside the base body of the high-toughness ceramic member according to the present invention.
【図４】気孔による亀裂進展阻止効果を説明する図。FIG. 4 is a diagram for explaining a crack growth prevention effect by pores.
【図５】気孔とウイスカーとの相乗効果を説明する図。FIG. 5 is a diagram illustrating a synergistic effect of pores and whiskers.
【図６】本発明に係る高靭性セラミックス部材と、従来
のウイスカー強化セラミックス部材とについての荷重−
変位曲線の比較を示すグラフ図。FIG. 6 shows the load of the high toughness ceramic member according to the present invention and the conventional whisker reinforced ceramic member.
The graph figure which shows the comparison of a displacement curve.
１１…高靭性セラミックス部材，１２…表層部，１３…
表層部 １４…遷移層，１５…遷移層，１６…最多孔性部，１７
…基体 ２１…高靭性セラミックス部材，２２…基体，３１…亀
裂，３２…気孔 ４１…気孔，４２…ウイスカー，４３…剥離点。11 ... High toughness ceramic member, 12 ... Surface layer portion, 13 ...
Surface layer portion 14 ... Transition layer, 15 ... Transition layer, 16 ... Most porous portion, 17
... substrate 21 ... high toughness ceramic member, 22 ... substrate, 31 ... cracks, 32 ... pores 41 ... pores, 42 ... whiskers, 43 ... peeling points.
Claims (2)
を母材とし、該母材より破断歪が大きいセラミックス繊
維を強化材として５０重量％まで含み得るセラミックス
材料の焼結体からなり、該焼結体は、独立気孔を内包す
る多孔性基体と、この基体の１の主表面に一体的に焼結
された緻密な表層部とを有し、該基体は、最大気孔率を
有する最多孔性部を、該表層部から離間して、かつ該表
層部と実質的に平行に延在して有し、さらに該基体内に
おいて、該１の主表面から該最多孔性部に向かって、気
孔率が漸増していることを特徴とする高靭性セラミック
ス部材。1. A sintered body of a ceramic material, which comprises oxide-based or non-oxide-based ceramics as a base material, and up to 50% by weight of a ceramic fiber having a breaking strain larger than that of the base material as a reinforcing material. The bonded body has a porous substrate containing independent pores and a dense surface layer portion integrally sintered on one main surface of the substrate, and the substrate has the highest porosity and the highest porosity. Has a portion extending from the surface layer portion and substantially parallel to the surface layer portion, and further has pores in the substrate from the main surface of 1 toward the most porous portion. A high toughness ceramic member characterized in that the rate is gradually increasing.
て、部材の厚さ方向に沿った径と、それに直交する方向
の径との比が０．１〜１０であって、該基体の最多孔性
部における気孔率が４０％以下である、請求項１記載の
高靭性セラミックス部材。2. With respect to the pores existing inside the base of the member, the ratio of the diameter along the thickness direction of the member to the diameter in the direction orthogonal thereto is 0.1 to 10, and the maximum number of the base is present. The high-toughness ceramic member according to claim 1, wherein the porosity of the porous portion is 40% or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4054987A JPH05254950A (en) | 1992-03-13 | 1992-03-13 | High toughness ceramic member |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4054987A JPH05254950A (en) | 1992-03-13 | 1992-03-13 | High toughness ceramic member |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05254950A true JPH05254950A (en) | 1993-10-05 |
Family
ID=12986003
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4054987A Pending JPH05254950A (en) | 1992-03-13 | 1992-03-13 | High toughness ceramic member |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05254950A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001172090A (en) * | 1999-10-08 | 2001-06-26 | Toray Ind Inc | Ceramics |
-
1992
- 1992-03-13 JP JP4054987A patent/JPH05254950A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001172090A (en) * | 1999-10-08 | 2001-06-26 | Toray Ind Inc | Ceramics |
| JP4719965B2 (en) * | 1999-10-08 | 2011-07-06 | 東レ株式会社 | Ceramics |
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