高温域での一定あるいは繰返し応力下における構造用セラミックスのき裂治ゆ挙動

概要

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Three types of structural ceramics, Al_2O_3/SiC, mullite/SiC and Si_3N_4/SiC having excellent crack-healing ability were sintered. A semi-elliptical surface crack of 75-110 μm in surface length was made on each specimen with a Vickers indenter. The basic crack-healing behavior was studied systematically on Al_2O_3/ SiC as a function of crack-healing temperature and time. Three point bending tests were carried out to investigate the strength of crack-healed samples. The specimens containing the semi-elliptical surface crack were healed under static or cyclic bending stress on mullite/SiC and Si_3N_4/SiC. It was shown that a crack could be healed completely either under a static or a cyclic stress. The competition between self crack-healing rate (S_<CHR>) and crack growth rate (C_<GR> = da/dt) determines the crack-healing behavior under stress: (i) In case of S_<CHR>> C_<GR>, a crack can be healed completely even under stress and recover of strength is complete. (ii) In case of S_<CHR>≒C_<GR>, a crack cannot be healed completely and recover of strength is insufficient. (iii) In case of S_<CHR> < C_<GR>, the specimen fails due to crack growth under stress.
社団法人日本セラミックス協会の論文
2002-08-01