Crack-Healing Behavior under Stress, Strength and Fracture Toughness of Mullite/SiC Whisker Composite Ceramic
Masato ONO, Wataru ISHIDA, Wataru NAKAO, Kotoji ANDO, Shuntaro MORI and Masahiro YOKOUCHI
Abstract:Mullite / SiC whisker composite ceramic was sintered. The three point bending specimen was made from the composite ceramic. A semi-elliptical surface crack up to 400 m in diameter (aspect ratio 0.9) was introduced on the specimen. The basic crack-healing behavior was studied systematically as a function of crack-healing temperature, and the bending strength of the crack-healed sample was also tested systematically. Followings are main conclusions obtained; (1) The mullite reinforced by SiC whiskers exhibited a large crack-healing ability. (2) The fracture toughness (KIC) of the mullite composite was increased about 60% by the SiC whisker reinforcement. (3) The crack-healed mullite exhibited lower bending strength(B) than that of the crack-healed base material by 150`200 Mpa. (4) The mullite was able to heal a crack even under constant or cyclic stresses. The critical stress intensity factor (KHSC) for the healing was found to be 2.1 MpaEm1/2. Key Words:Mullite, SiC whisker, Crack-healing, Fracture toughness, Strength, In-situ crack-healing