A comparative study of the thermal oxidation behavior of a Ni-Cr-base superalloy, Inconel 617, with and without a refractory ceramic coating layer has been conducted and a significant enhancement in the thermal oxidation resistance was obtained by employing the refractory ceramic coatings. 2.5-3.0 mu m thick TiAlN- or Al2O3-coated Inconel 617 samples showed much lower mass changes than bare Inconel 617 after annealing at 1000 degrees C for up to 48 h by suppressing the inhomogeneous formation of Cr2O3 at the surface region through the reaction between oxygen and grain boundary-diffused Cr.
Keywords: thermal oxidation resistance; a Ni-Cr-base superalloy; Ceramic coating; Inconel 617; surface oxidation; Cr2O3 formation