Thermal shock behaviors of plasma sprayed YSZ/TiAlCrY system on TiAl alloys

Abstract

TiAl alloys are promising structural materials in the field of gas turbine engines, due to their low density and high specific strength. Applying thermal barrier coatings (TBCs) is an effective method to increase the service temperature and lifetime of TiAl alloys. In this work, a YSZ/TiAlCrY bilayer system was fabricated by air and vacuum plasma spray techniques on TiAl alloys. The thermal shock behavior was focused on and compared with the traditional YSZ/NiCrAlY system by means of a water-quenching test at 1100 °C. The results show that the YSZ/TiAlCrY system exhibited excellent thermal cycling lifetime with over 210 cycles, which was almost 3 times that of the traditional YSZ/NiCrAlY system on Ni-based superalloys. The failure mechanism was analyzed based on microstructural observations and residual stress calculations. It is found that without the formation of new brittle phases at the interface and suitable CTE were the key factors for the excellent thermal shock resistance of the YSZ/TiAlCrY system on TiAl alloy substrates.