Abstract
Thermally-sprayed MCrAlY (M = Ni and/or Co) + yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs) are widely used in industrial gas turbines to suit the needs of operating at higher temperatures and burning conventional and hydrogen containing fuels, where oxidation and water vapor resistance as well as thermal cycling life are of great importance. As a slow growing Al2O3 thermally-grown oxide (TGO) layer on the MCrAlY bond coats favors the oxidation resistance, it may also favor the water vapor resistance because of its higher stability compared with Cr2O3 and SiO2 at elevated temperatures. As increasing the Al content in MCrAlY favors oxidation resistance, it can be anticipated that for a determined Al concentration, reducing the Cr/Al ratio may favor the oxidation resistance as well. This work investigates the high temperature performance of thermally sprayed TBCs with high velocity oxy-fuel (HVOF) produced NiCrAlY bond coats and air plasma spray (APS) produced YSZ topcoat in furnace cycling and water vapor environments.