Fatigue strength properties of crack healed mullite/SiC composite ceramics
Ando Kotoji; Tsuji Kiichi; Ariga Makoto; Sato Shigemi
Abstract:Mullite/SiC composite ceramics was sintered. Three point bend specimen was made according to JIS standard. Semi-elliptical surface crack of 100 mm in diameter was made on the specimen. By using four kinds of specimens (as-received, heal treated as-received, pre-cracked and pre-crack healed), cyclic fatigue and static fatigue strength of the specimen were tested systematically at room temperature. The main conclusions obtained are following: (a) Mullite/SiC composite ceramics has ability to heal crack. (b) Crack healed specimen (heal treated as-received and pre-crack healed) showed higher cyclic and static fatigue strength than as-received specimen, and this fact was caused by crack healing. (c) Crack healed part has enough fatigue strength and most fracture occurred outside the pre-cracked zone in pre-crack healed specimen. Key Words:mullite/SiC ceramics, crack healing, bending strength, recovery of strength, cyclic fatigue strength, static fatigue strength, crack initiation site