High temperature fatigue strength of crack-healed Al_2O_3 toughened by SiC whiskers

摘要

Al_2O_3 reinforced by SiC whiskers (Al_2O_3/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℃ for 1 h in air, and static and cyclic fatigue strengths were systematically investigated at room temperature, 900℃, and 1100℃ 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 Al_2O_3/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.