Crack Healing Behavior and High Temperature Strength of Mullite/SiC Composite Ceramics
Ando Kotoji; Tsuji Kiichi; Hirasawa Toshikazu; Kobayashi Yasuyoshi; Chu Min Cheol; Sato Shigemi
Abstract:A mullite/SiC composite ceramic was sintered. Four point bend tests were conducted according to JIS standard. Semi elliptical surface crack of 100 or 200mm diameter was made on the specimen. For four kinds of specimens (as received, heal treated, pre cracked and heal treated cracked), crack healing behavior and high temperature strength were tested systematically. The main conclusions were obtained as follows: (a) Mullite/SiC composite ceramic has ability to heal crack. (b) Best healing condition was found to be 1300 deg., in air for 1 h. (c) Maximum crack size to be healed is semi elliptical crack of 100mm in diameter. (d) Crack healed part has enough strength up to 1100 deg. and most specimen failed outside the pre cracked zone and healed crack is not sensitive to static fatigue. Key Words:mullite/SiC ceramics, crack healing, bending strength, recovery of strength, high temperature strength, healing condition, sensitivity to static fatigue