The mechanical and thermal properties, CMAS corrosion resistance, and the wettability of novel thermal barrier material GdTaO4

Because the CMAS corrosion and phase transformation at elevated temperatures above 1250 °C have limited the applications of traditional YSZ , the design of novel thermal barrier materials is a hotspot. GdTaO 4 is considered as a type of potential novel thermal barrier material owing to its low thermal conductivity . In this study, the mechanical and thermal properties, CMAS corrosion resistance , and the wettability of the GdTaO 4 were studied and compared with that of YSZ. The results show that the coefficient of thermal expansion and hardness of GdTaO 4 are 14.1 × 10 −6  K −1 (1350 °C) and 534.2 Hv 0.3 respectively. The thickness of CMAS reaction layer of GdTaO 4 is ~30.8 μm after 24 h reaction at 1350 °C, which is thinner than that of YSZ. After corrosion reaction, the CMAS glass aggregated instead of completely disappearing or continuously extending over the surface of GdTaO 4 . The main reaction product is Ca 2 Ta 2 O 7 , and the anorthite phase may not be detected, which is similar to YTaO 4 . By comparison, the dense substrate of YSZ became porous and CMAS glass has disappeared after 10 h. CMAS corrosion at 1350 °C. The on-line contact angle results show that the wettability of CMAS on GdTaO 4 is worse than that on YSZ at 1350 °C, while the opposite of the work of adhesion, which indicates that GdTaO 4 can remove liquid CMAS more easily than YSZ TBCs during the service. Furthermore, the corrosion depth and areas of GdTaO 4 are smaller than those of YSZ in the same situation. These findings suggest that GdTaO 4 possesses better high-temperature properties and CMAS corrosion resistance than YSZ as a kind of potential of thermal barrier material.