Thermophysical properties and interfacial stability of mixed-phase ytterbium silicates with Hf_0.81Y_0.19O_1.905

Thermal environmental barrier coatings (TEBCs) are deemed enabling technologies for high-performance SiC_f/SiC CMCs of gas-turbine engines. Mixed Phase Ytterbium Silicate (MPYS) combines the thermal compatibility of Yb₂Si₂O₇ with the corrosion resistance of Yb₂SiO₅, effectively resolving the critical thermomechanical stresses challenge of multilayer TEBCs. This paper investigates the thermophysical properties and corrosion resistance of MPYS, and further examines the high-temperature interfacial stability of Hf_0.81Y_0.19O_1.905(YSH19)/ MPYS diffusion couples at 1300℃ and 1500℃. The results show that as the content of Yb₂Si₂O₇ increases, the coefficient of thermal expansion (CTE) of MPYS decreases and the thermal conductivity increases. After heat treatment, Yb₂SiO₅ at the interface tends to decompose into Yb₂O₃ and SiO₂, resulting in the formation of a Yb₂Si₂O₇ layer. Yb diffuses into the YSH19 layer, further stabilizing the C phase. This research holds certain guiding significance for the future development of TEBCs.