High-temperature oxidation behavior and surface roughness evolution of VPS NiCrAlY coating

In this work, as a background to the development of high temperature environmental protection coating technology, the structural transformation of vacuum-plasma sprayed NiCrAlY coating has been studied, including the oxidation behavior, elastic modulus, microhardness, and surface roughness. Coating was oxidized isothermally at a 1,273 K for different time periods up to 1,000 h in order to form the oxide scale layer. The results showed that the oxide scale and weight gain increased proportional to the exposure time. The surface roughness and hardness decreased after isothermal exposure, but they are not proportional to the exposure time. The oxide scale growth was concentrated in the valleys of the surface at the early 1 h exposure (decreasing surface roughness), whereas the oxide scales over a longer perspective (time period), grew on the convex surface (increasing surface roughness).