High-temperature J-integral measurements and micromechanisms at crack tip of ceramic materials

Abstract

An alumina contaInIng 3% glassy phase was investigated by three-point bending experiments in a closed loop testing machine at room temperature, 800, 900, and 1000°C. A high dependence of K_1C on loading rate was found, especially at 900°C. To investigate the loading-rate influence J-integral measurements were performed at 800, 900, and 1000°C and for comparison K_1C values on pure alumina were measured at room temperature and 900°C. It is suggested that the loading-rate dependence is caused by the influence of the second phase on crack nucleation and failure time.