Thermal insulation performance and thermal shock resistance of plasma-sprayed TiAlCrY/Gd2Zr2O7 thermal barrier coating on γ-TiAl alloy

TiAl alloy has attracted widespread attention as an alternative material for nickel superalloy in aerospace, while the poor oxidation resistance above 800 °C limits its application. In this work, TiAlCrY/Gd2Zr2O7 thermal barrier coating was fabricated by plasma spraying on TiAl alloy and its thermal insulation performance and thermal shock resistance were investigated. Results obtained indicate that the thermal insulation ability of TiAlCrY/Gd2Zr2O7 coating was 230–390 °C at 1100 - 1300 °C, which was approximately 40 % higher than that of TiAlCrY/YSZ coating. What's more, the thermal shock lifetimes of the TiAlCrY/Gd2Zr2O7 coating were 300, 100 and 50 cycles at 1000, 1100 and 1200 °C, respectively, which were almost 25 times of the NiCrAlY/Gd2Zr2O7 coating on superalloys. The low thermal conductivity of Gd2Zr2O7 layer was responsible for the remarkable thermal barrier property of the coating. Residual stresses in the TiAlCrY/Gd2Zr2O7 coating were studied by XRD and Raman, and finite element simulation method was used to discuss the failure mechanism of the coating system. It suggested that the close coefficients of thermal expansion among TiAlCrY, Gd2Zr2O7 coatings and TiAl-alloy substrate, and the resulting lower residual stresses contributed to its durable thermal shock resistance.