Development of structural ceramics having large crack-healing ability and fracture toughness

Al2O3 reinforced by SiC whiskers (Al2O3/SiC-W) was hot pressed to investigate the crack-healing behavior. Semi-elliptical surface cracks of 50 to 450 mu m in surface length were introduced using a Vickers indenter. The specimens containing pre-cracks were crack-healed at temperatures between 1000 degrees C and 1300 degrees C for 1h in air, and their strengths were measured by three-point bending tests at room temperature and elevated temperatures between 400 degrees C and 1300 degrees C. The results show that Al2O3/SiC-W possesses considerable crack-healing ability. The surface cracks with length of 2c = 100 mu m. could be healed by crack-healing at 1200 degrees C or 1300 degrees C. for 1h in air. The maximum crack size that can be healed for Al2O3/SiC-W is 2c = 200 mu m. Fracture toughness of the material was also determined. As expected, the SiC whiskers made their Al2O3 tougher.