Influence of micro-structure on erosion resistance of plasma sprayed 7YSZ thermal barrier coating under gas turbine operating conditions

This paper presents the results of an experimental investigation of the effect of topcoat micro-structure on the erosion resistance of air plasma sprayed 7 wt% YSZ thermal barrier coating (TBC) at high temperature. Two sets of air plasma sprayed YSZ TBCs of differing micro-structures (porosities of 12.9 ± 0.5% and 19.5 ± 1.2%) were tested in a high temperature erosion tunnel to simulate modern gas turbine engine's operating conditions. The tests were conducted over a range of temperatures between 537 °C and 980 °C, gas velocities between 122 m/s and 305 m/s, and impingement angles between 20° and 90°. The two types of erodent powders used in the erosion tests were nominal 27 µm white fused Alumina and nominal 15 µm A3 test dust. The results demonstrate reduced erosion resistance associated with increased porosity in the topcoat layer.