セラミックスの高温き裂進展挙動(SCG)とその評価法

概要

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Behavior and test method of subcritical crack growth (SCG) at elevated temperatures were investigated on an alumina with 90% purity. The proposed test method enabled to measure SCG at temperatures over 1000℃ using the piston displacement of testing machine and fractographic information. In order to evaluate SCG be havior based on the linear elastic fracture mechanics (LEFM) , Iarger specimens are recommended, because a small scale creep (SSO condition is required in ex pressing the crack tip singular stress field by LEFM parameter, i.e. stress intensity factor K. Since creep is dependent on both thermal and mechanical factors, re quirement of SSC condition, which implies that the creep damage zone is localized at the crack tip region, may be influenced by those factors. Detailed observa tions of SCG behavior at 900 and 1050℃ revealed that a nrain crack grew by coalescences with microcracks ini tiated in the creep damage zone at the crack tip. Thus, tortuosity of SCG path increased with increasing size of the creep damage zone. Temperature dependence of SCG characteristics was discussed in terms of the crack growih mechanism and creep deformation scale.
社団法人日本セラミックス協会の論文
1994-05-01