Microstructure and oxidation resistance of a YSZ modified silicide coating for Ta-W alloy at 1800 °C

[Display omitted] •A Si-Mo-YSZ coating was prepared on Ta-W alloy by slurry reaction sintering method.•The coated sample remained intact after oxidation at 1800 °C for 10 h.•The coating withstood 218 shock heating cycles from room temperature to 1800 °C.•The excellent performance was attributed to the dense SiO2-ZrO2-ZrSiO4 scale.•Microstructure evolution and failure mechanism of the coating were analyzed. To develop an ultra-high temperature resistant coating for a reusable thermal protection system, a YSZ-modified Si-Mo coatings were prepared on Ta-10 W alloy by slurry reaction sintering method. The coating had a MoSi2-ZrSi2-SiO2 outer layer and a TaSi2-WSi2 inner layer. The coated sample remained intact after oxidation at 1800 °C for 10 h, while the untreated alloy was pulverized after 6 min. The coating withstood more than 200 shock heating cycles from room temperature to 1800 °C. Its outstanding oxidation resistance is attributed to its thermal matching with the alloy and formation of protective SiO2 scale containing high-melting ZrSiO4 and ZrO2.