Elevated Temperature Erosion of Plasma Sprayed Thermal Barrier Coating

Yttria-stabilized zirconia (YSZ) is used extensively as a ceramic top coat of thermal barrier coating (TBC) system in land-based gas turbines and aero engines. TBC enables modern engines to operate at significantly higher gas temperatures. TBCs are subjected to solid particle erosion at elevated temperature, especially during the operation of aero engines in sandy terrain. Thus, the objective of the present investigation is to evaluate the impact erosion response of these coatings as a function of various eroding conditions. Toward that purpose, YSZ TBC was deposited on Ni base alloy using air plasma spraying technique. The microstructural features of the coating are evaluated, and coated samples are subjected to erosion test employing a high-temperature air jet erosion testing machine at various temperatures, at different impact velocities, and at different impact angles. The results show a brittle erosion response of TBC at all temperatures. The erosion rate of TBC is generally independent of temperature under the normal impact, and it increases with temperature under oblique impact at high impact velocity. Intersplat adhesion governs the erosion mechanism.