Wet corrosion of nitride PVD films in supercritical solutions

Nitride TiN, TiAlN and CrN films exhibit a high performance with respect to steel corrosion protection in supercritical water. However, for practical applications their corrosion resistance in water solutions is more important. Wet corrosion of nitride PVD films in neutral, acid and alkaline supercritical solutions was studied. The highest stability of the films was revealed in neutral sodium chloride and alkaline CH3NH2 solutions. In the latter case regular cubic spinel crystals were formed on the surface of TiAlN films. Acidic solutions destroy nitride films due to growth of corrosion products beneath the coating layer.