Abstract
If the turbine inlet temperature (TIT) of gas turbine exceeds 1000℃, attaining 35% efficiency becomes promising. Silicon nitride ceramic is well known as a typical material for hot components of the gas turbines. In utilizing ceramics as the hot components of gas turbines, foreign object impact damages are the main issue in the ceramic engines. In this study, we examined the critical impact velocity, which resulted in the fracture of the ceramic test pieces. In the experiment, a 1 mm diameter samarium cobalt ball impacted on the type SN282 (Kyocera) silicon nitride ceramic test piece. The test piece was hold under the actual service condition, i.e. the elevated temperatures and the pre-loading tensile loads pertinent to the centrifugal force. The main results so far obtained were: Both the elevated temperature and the pre-loading stress decreased the critical impact velocity lower than that under the room temperature without stress. The effects of the temperature and the stress on decreasing the critical velocity were not simply additive.
