Comparison of erosion rate of EB-PVD and plasma sprayed TBC

A thermal barrier coating (TBC) consisting of platinum-aluminide bond coat and 7wt-% yttria stabilized zirconia (7YSZ) ceramic top coat deposited by electron beam physical vapour deposition (EB-PVD) system cast Ni-base superalloy CM-247LC. The erosion behaviour of the EB-PVD and air plasma sprayed (APS) TBCs are compared. The APS TBC consists of 7YSZ top coat and CoNiCrAlY bond coat on Inconel 738 substrate. Erosion responses of TBCs have been examined as a function of temperature. The erosion rate of EB-PVD TBC was significantly lower than that of APS TBC. Erosion rate of EB-PVD TBC decreased with test temperature. APS TBC exhibits mostly temperature independent erosion rate. The material removal mechanism of EB-PVD TBC was by the formation of parallel cracks in the ceramic layer close to its surface and their subsequent joining. The material is removed by propagation of subsurface cracks along the splat boundaries in case of APS TBC.