Characterization of Yb2SiO5-based environmental barrier coating prepared by plasma spray-physical vapor deposition

Due to the high-input power compared to atmospheric plasma spraying (APS), plasma spray-physical vapor deposition (PS-PVD) can primarily achieve a splat-like deposition, allowing for the preparation of high-density environmental barrier coatings (EBCs). In this paper, dense Yb2SiO5-based coatings are prepared by PS-PVD at different substrate temperatures. It was found that the coating deposited at the substrate temperature of 700 degrees C contained a large amount of silicon-rich amorphous phase. When the substrate temperature increased to 1100 degrees C and a slow cooling process after deposition was involved, a coating with high crystallinity of -77% and low porosity of less than -2% was achieved. Phase evolution of the coatings was studied by a semi-in-situ hightemperature X-ray diffractometer. During the heating process, metastable phases X1-Yb2SiO5 and alpha-Yb2Si2O7 emerged and transformed into stable phases following high-temperature treatment. Furthermore, the effects of long-term thermal aging at 1300 degrees C on the microstructure, phase composition, thermal conductivity, and hardness of the coating prepared at the substrate temperature of 1100 degrees C were found to be limited.