Thermal Cycling Behavior of Plasma Sprayed Segmented Thermal Barrier Coatings

Thermal barrier coatings (TBCs) with different levels of segmentation crack densities (Ds) were sprayed at different substrate temperatures (Ts). Thermal cycling resistance of the TBC specimen was examined. The segmented coating significantly improved the thermal cycling resistance as compared to the traditional nonsegmented coating. Maximum thermal cycling lifetimes were achieved in the coating with a crack density level of 2.2 mm^-1. New segmentation cracks were hardly generated during thermal cycling testing. Spallation of segments within the segmented coating occurred, which is different from spallation of the whole coating from substrate in the case of traditional coating. Oxidation of bond coat and limited phase decomposition of YSZ topcoat were considered as not responsible for the failure of TBCs.