MCrAlY(M=CoNi, NiCo, Ni, Co etc.)coatings are widely applied to protect substrates from oxidation and corrosion under high temperature environment. Those coatings are generally coated by various thermal spray processes: LPS, HVOF, and APS. In particular, it is recognized that high temperature oxidation resistant properties of APS-MCrAlY coatings are inferior to other spray processes(LPS and HVOF), however the process cost of APS is lowest. In this study, high-temperature oxidation resistant properties of MCrAlY coatings deposited by APS, LPS and HVOF were compared. Furhtermore, mechanism of oxidation during thermal spraying process was investigated. It was confirmed that APS-MCrAlY coatings using a large-size alloy powder deposited under Ar-He plasma gas indicated the superior high-temperature oxidation resistance. Finally, the oxidation mechanisms, which could be occurred during thermal spraying process and high-temperature exposure treatment, were discussed based on SEM images and EDX analysis.

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