Long-term high temperature exposure behavior of MCrAlY bond coat fabricated by vacuum plasma spray

Among the gas turbine components for power generation, the thermal barrier coating(TBC) for high temperature exposure parts(combustor, vane, blade, etc.) have got great attention. Because the performance of these parts are directly related to the engine efficiency and lifetime, various researches have focused on further improvement of TBCs. Unfortunately, research paper which dealt with the long-term(up to 15,000 hours) high temperature exposure behavior of bond coat is limited. In this study, three different commercial MCrAlY-based materials(NiCoCrAlY, NiCoCrAlY + Hf, Si, NiCoCrAlY + Hf, Si, Ta, Re) were selected as bond coats. The bond coats were fabricated by using vacuum plasma spraying(VPS). A common 8YSZ(8wt% yttria-stabilized zirconia) top coat was fabricated by using atmospheric plasma spray(APS). To analyze the long-term high temperature exposure behavior of bond coat, isothermal oxidation test was performed at 1,000℃ up to 15,000 hours. The microstructural characterization of different bond coats was conducted before and after isothermal oxidation. The results indicated that different elements in as-coated bond coat affected the thermally grown oxide formation mechanism and inter-diffusion between superalloy substrate and bond coat. It is expected that the results in this research will be useful to predict the thermal exposure behavior of high temperature components.