647 窒化ケイ素/SiC セラミックスの高温疲労特性に及ぼすき裂治癒プロセスの影響

抄録

Si_3N_4/SiC composite ceramics were sintered and subjected to three-point bending. A semi-circular surface crack of 100μm in diameter was made on each specimen. We systematically studied crack-healing behavior and static fatigue strength at 1000℃ by using three kinds of specimens (smooth, cracked and crack-healed). The main conclusions are as follows. Si_3N_4/SiC composite ceramics could heal a crack even under constant or cyclic stress at 1000℃ completely. The fatigue limit at 1000℃ depended on the healing process. The sample crack-healed at 1000℃ had sufficient static fatigue strength at 1000℃. New crack healing process have been proposed.