Al2O3 reinforced by SiC whiskers (Al2O3/SiC-W) was sintered in order to investigate the fatigue strength of crack-healed specimens at high temperature. A semi-elliptical surface crack of 100μm in surface length was introduced on each specimen surface. These specimens were crack-healed at 1300°C for 1 h in air, and static and cyclic fatigue strengths were systematically investigated at room temperature, 900°C, and 1100°C by three-point bending. The static and cyclic fatigue limits of the crack-healed specimens were more than 70% of the average bending strength at each testing temperature. Crack-healed specimens of Al2O3/SiC-W were not sensitive to static and cyclic fatigues at room temperature and high temperatures. Therefore, the combination of crack-healing and whisker reinforcement can play an important role in increasing static and cyclic fatigue strengths at high temperature.
Al2O3 reinforced by SiC whiskers (Al2O3/SiC-W) was hot pressed to investigate the crack-healing behavior. Semi-elliptical surface cracks of 50 to 450μm in surface length were introduced using a Vickers indenter. The specimens containing pre-cracks were crack-healed at temperatures between 1000°C and 1300°C for 1h in air, and their strengths were measured by three-point bending tests at room temperature and elevated temperatures between 400°C and 1300°C. The results show that Al2O3/SiC-W possesses considerable crack-healing ability. The surface cracks with length of 2c=100μm could be healed by crack-healing at 1200°C or 1300°C for 1h in air. The maximum crack size that can be healed for Al2O3/SiC-W is 2c=200μm. Fracture toughness of the material was also determined. As expected, the SiC whiskers made their Al2O3 tougher.