Wear behavior of novel abradable porous Yb2Si2O7-CaF2-PHB coatings fabricated by atmospheric plasma spraying

The abradable sealing coatings (ASCs) matched with ceramic matrix composites (CMCs) can improve engine efficiency and reduce fuel consumption. A study of plasma -sprayed porous Yb2Si2O7-20 vol% CaF2 with various contents of poly-p-hydroxybenzoate (PHB) as ASCs compatible with CMCs is reported. The microstructure and phase composition, Rockwell hardness, wear behaviors and abradability of the coatings were comparatively studied. The results show that the porosity increased and the hardness decreased as the PHB content was increased, and the coating containing 20 vol% PHB had a minimum hardness of about 65.2 HR45Y and a maximum porosity of about 39.2%. The friction coefficients and IDR values decreased, wear depth and volume wear rates of the coatings effectively improved with the increase of porosity. The wear mechanisms were analyzed based on the observation of the worn surfaces. This work might provide some guidance for the design and application of ASCs for CMCs.