Improved corrosion protection of CrN hard coating on steel sealed with TiOxNy-TiN composite layers

Based on the excellent conformality and uniformity of atomic layer deposition (ALD), ALD thin films can seal the defects in magnetron sputtered CrN coating. In this work, atomic layer deposited TiN layer is adopted to seal CrN to improve its anti-corrosion properties. The oxidization of TiN forms TiOxNy-TiN composite layer including TiN bottom layer and TiOxNy upper layer, which can limit the charge transport, inhibit the diffusion of corrosive media, such as chlorine ions. Therefore, the addition of TiOxNy-TiN sealing layer significantly improves the corrosion resistance of CrN coated steel, and decreases its corrosion current density, due to the synergistic effect of TiOxNy and TiN in the composite sealing layer.