Test atmospheres affecting voids distribution on MCrAlY-bond coats for TBCs at 1050 °C

Abstract The oxidation behaviour of thermal barrier coatings with a NiCoCrAlY bond coat at 1050 °C in different atmospheres was investigated. Water vapour contributed to fewer defects and lesser internal growth of Al2O3 in the bond coat. Additionally, the presence of excess water vapour in the air + water vapour atmosphere suppressed the local inward oxide growth. Electron backscatter diffraction and transmission electron microscopy analyses were performed to investigate the influence of water vapour on the grain growth of alumina. The grain size of Al2O3 depended on the water vapour content. The driving forces for the morphological distribution of voids in various atmospheres were discussed.