Temperature Dependence of Impact Damage in a Si<sub>3</sub>N<sub>4</sub> Disk by a Spherical Particle

Abstract

A model experiment for examining impact damge dependence on temperature is conducted on Si3N4 for turbine use. A zirconia sphere is shot onto a Si3N4 disk at RT and at 1200°C, and then surface damage as well as internal damage is examined. The results indicate that a generated crack system changes from a Hertzian cone crack to a median crack in accordance with the experimental temperature change. It is concluded that the hardness degradation at 1200°C generated a change in the stress field from elastic to elastic/plastic, resulting from softening of grain boundary glassy phase.