The influence of Cr on the oxidation behavior of a sputtered Pt+γ’ phase-equilibrium coating at 1150 ℃

Two sputtered phase-equilibrium coating (Pt+γ’ and Pt-Cr+γ’ coating) were manufactured in this work. No TCPs appeared around the interface of coating/superalloy after being oxidized at 1150 ℃ for 1000 h. The addition of chromium changes the oxidation kinetics of Pt-Cr+ γ’ coating both in transient and steady oxidation stage. In transient-oxidation stage, chromium accelerates the transition of aluminum oxide from θ-Al2O3 to α-Al2O3, which lowers the compressive stress in oxide scale. The presence of Cr in coating also refines the grain size of α-Al2O3 scale, which leads to a higher growth rate in the later steady oxidation-stage.