Influence of the interface healing between the splashed particles and underlying bond coating on the cyclic oxidation behavior of LPPS MCrAlY bond coats

The growth behavior of thermally grown oxide (TGO) on the bond coats of thermal barrier coatings (TBCs) has a significant impact on the TBCs life time. The splashed particles on the thermally sprayed MCrAlY bond coat surface have weak bonding with the underlying bulk coating, which will lead to the formation of mixed oxides and promote the failure of TBCs. In this study, the interface between the splashed particles and underlying bond coating was healed by vacuum pre-treatment (pre-diffusion). The bond coats were divided into three groups by the ways of pre-treatments before deposition of the ceramic top coating. Two groups of bond coats were subjected to two different pre-treatments (pre-diffusion-oxidation and pre-oxidation) prior to cyclic oxidation tests. The third bond coats were directly subjected to the same cyclic oxidation tests. Results show that the different TBCs present different cyclic oxidation behavior. The TBCs with pre-diffusion-oxidation exhibited the best cyclic oxidation resistance, and the ones without pre-treatment had the worst cyclic oxidation resistance. It is revealed that the healing of interface between the splashed particles and underlying bulk coating can effectively improve the cyclic oxidation resistance. This study will benefit the development of advanced TBCs with long life time and high reliability.