Measurement on the thermal barrier ability of ceramic coatings in a flame thermal shock tester

Abstract

Ceramic materials are widely used at high temperatures due to their low thermal conductivity. Thermal barrier coatings (TBCs) have been applied in hot sections in industrial gas turbines and air engines. The measurement of the thermal barrier ability of the TBCs is very important for coating property evaluation, that can be done in hot gases with temperature gradient through the coatings. In this study, a flame thermal shock tester was used for such investigation. Thick TBC, containing a MCrAlY bond coat and a YSZ top coat, was sprayed onto a superalloy substrate by air plasma spray (APS) process. In the test, hot flame impacted on the top coat surface with the temperature controlled by an infrared thermometer. A thermocouple was attached onto the backside of the substrate to measure the backside temperature. Therefore, the temperature gradient in the TBC can be evaluated. The thermal barrier ability of the TBCs in different back cooling rate was studied.