窒化けい素セラミックスの曲げ応力下における自己き裂治ゆ挙動とき裂治ゆ温度での強度特性

概要

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S_i3N_4/SiC composite ceramics were sintered and subjected to three-point bending. A semi-elliptical surface crack of 100μpm in surface length was made on each specimen. A crack was healed under static bending stress of 210 MP_a at 800, 900 and 1000℃. Applied stress of 210 MP_a is 〜70% of the bending strength of as-cracked specimen. Bending strength and static fatigue strengths of crack-healed specimens were systematically investigated at each crack-healed temperature. The bending strength of crack healed specimen showed almost the same value as the smooth specimen. Thus, Si_3N_4/SiC composite ceramics could heal a crack even under static bending stress of 210 MP_a at 800, 900 and 1000℃. Moreover, crack-healed zone had sufficient static fatigue strength at each crack-healed temperature. These conclusions indicate that Si_3N_4/SiC composite ceramics has the ability to heal a crack under service condition, i.e. high temperature and applied stress.
社団法人日本機械学会の論文
2002-07-25