High-Temperature Wear and Abradable Behaviors of Yb₂Si₂O₇-CaF₂ Composite Coatings Fabricated by Atmospheric Plasma Spray

Ceramic matrix composites (CMCs) have become important structural materials of aero-engines under elevated operating temperature while the abradable ceramic coatings matched with CMCs are seldom reported. In this work, the atmospheric plasma spray (APS) technique was used to fabricate and design Yb2Si2O7-based coatings with various contents of CaF2. The phase composition and microstructure of the coatings, as well as Rockwell hardness, were characterized. The wear and abradable behaviors of the coatings including friction coefficients and volume wear rates were evaluated at room temperature and 900 degree celsius, respectively. The results show that the Rockwell hardness and friction coefficients decreased, and the volume wear rates of the coatings at room temperature significantly raised with the increase of CaF2 content. The coatings exhibited quite different behaviors at 900 degree celsius compared with those at room temperature owing to the lubricant effect of CaF2. The morphologies of the coatings after the wear tests were characterized and the possible failure mechanisms were analyzed, and this study may provide guidelines for the application of the abradable coatings suitable for CMCs.