Oxidation resistance of Cr2N and (Cr,W)2N coatings deposited on ferritic stainless steel

After oxidation at 800 °C for 1000 h, both the Cr2N and (Cr,W)2N coatings had bilayer scales comprising Cr2O3 and (Mn,Cr)3O4. The Cr2N and (Cr,W)2N coatings exhibited similar oxidation curves and a two stages of oxidation mechanism. The main reason for the occurrence of the dominant oxidation mechanism transfer is the growth of Cr2O3 and (Mn,Cr) 3O4 spinel. Moreover, the doping of W benefited the formation of a χ phase to precipitate at the oxide/coating interface, which acted as a diffusion barrier retarding the reaction rate between Cr and O.