Comparative Study on the Oxidation of CrN, TiCrN and TiAlN Coatings Deposited on a Steel Substrate by Ion Plating

Abstract

The oxidation behavior of CrN, TiCrN and TiAJN coatings deposited on a steel substrate by ion plating was studied between 973 and 1173K in atmospheric air. The oxidation resistance increased in the order of TiAlN, TiCrN and CrN, which were oxidized to TiO₂ and α-Al₂O₃, TiO₂ and Cr₂O₃, and Cr₂O₃, respectively. The α-Al₂O₃ layer formed on the TiAlN coating was too thin to resist oxidation, so that the oxidation resistance of TiAlN decreased rapidly at 1173K. The Cr₂O₃ layer formed on the TiCrN or CrN coating was comparatively thick, so that the oxidation resistance of these coatings was better than that of the TiAlN coating over entire testing temperatures. Particularly, the CrN coating displayed excellent oxidation resistance.