P59 Crack-healing behavior of Mullite/SiC multi-composite under stress and the resultant fatigue strength at the healing temperature

Abstract

Mullite reinforced with SiC whiskers and SiC particles, called here Mullite/SiC multi-composite, having high crack-healing ability and high fracture toughness was hot-pressed. A semi-elliptical surface crack was introduced on the test specimen. To heal the surface crack, the specimens were heat-treated at 1200℃ for 5h in air under constant or cyclic stress, and the resultant bending strength and fatigue strength were investigated at the healing temperature. The main conclusions are as follows: (1) The specimens could be healed even under stress, and the threshold stress for crack-healing was 170MPa. (2) The crack-healed specimens had high bending strength and high fatigue strength even at the healing temperature.