High temperature oxidation of TiCrN coatings deposited on a steel substrate by ion plating

The oxidation behavior of TiCrN coatings having compositions of Ti 36Cr 26N 38, Ti 31Cr 35N 34 and Ti 14Cr 52N 34 was studied between 700 and 1000°C in atmospheric air. The oxidation resistance of TiCrN coatings which were composed of TiN and CrN phases increased in the order of Ti 36Cr 26N 38, Ti 31Cr 35N 34 and Ti 14Cr 52N 34, implying that chromium within the coating played a decisive role in providing the oxidation protection. The oxides formed always consisted of TiO 2 and Cr 2O 3. During oxidation, all the involved elements diffused either outwardly or inwardly, depending on the concentration gradients. The substrate elements diffused outwardly toward the oxide-gas interface, oxygen from the atmosphere diffused inwardly and the coating elements diffused predominantly outward.