Microstructure evolution and thermal cyclic failure behavior of thermal barrier coatings with interface modification

Abstract

Thermal barrier coatings (TBCs) interface between bond coat and ceramic top coat is critical since most of degradation presented in this region as TBCs failure analysis. Shot peening, as a valuable surface engineering, has been applied for TBCs interface modification. The interface modification by shot peening process to the morphology evolution and degradation optimization still need to be studied. In this work, three different shot peening parameters have been selected for interface modification of as-prepared TBCs. The divergent column microstructure has been reduced and surface roughness improved with the shot peening parameters changing. Thermal cyclic failure behavior has been summarized as two mode, thermally grown oxide (TGO) growth induced spalling and interface premature delamination. TGO growth induced spalling dominated failure at roughly interface condition, while interface delamination dominated failure at smooth interface condition. This failure mode has explained the thermal cyclic life tendency, climbing up and then declined, of TBCs.