High-temperature oxidation of MCrAlY bond coats prepared by EB-PVD with PM ingots made of the thermal spray powder

A thermal barrier coating (TBC) system consists of a metallic bond coat and a ceramic top coat applied on a nickel or cobalt based superalloy substrate. The metallic bond coat in a TBC system is to provide oxidation resistance at high temperatures and to improve the lifetime of TBC systems by forming a suitable oxide layer. As a metallic bond coat, Aluminide or MCrAlY type overlay coatings (where M = Ni or Co or a combination of both) are commonly used. The bond coat determines the structure, composition and growth rate of the TGO, which plays a very important role in controlling the lifetime of the TBC systems.

In this study, the fabrication of the MCrAlY coating was tried using electron beam-physical vapor deposition (EB-PVD). MCrAlY ingots (hereafter referred to as PM ingots) as source materials for the EB-PVD bond coat were prepared by the hot isostatic pressing (HIP) of the thermal spray powders. The melting and evaporation behavior of PM ingots was investigated. And the high-temperature oxidation performance of the EB-PVD TBCs deposited on the EB-PVD bond coat were compared with those of EB-PVD TBCs deposited on the vacuum plasma sprayed (VPS) bond coat.