Laser Cladding of Hard TiO x N y /Ti Composite Coating on Ti Alloy

The notoriously low wear resistance of Ti alloys is impeding their engineering applications. In this work, a novel TiOxNy/α-Ti composite coating was developed by laser cladding TiO2 powders on a Ti-6Al-4V substrate in air. TiOxNy reinforcements were synthesized in situ via atmospheric nitriding of TiOx, chemically bonded with α-Ti matrix that solidified from the partially-melted substrate. The coating has an average hardness of 1417 HV0.3 (quadruple that of Ti-6Al-4V), superior to most composite coatings reported previously. The exceptionally high hardness of TiOxNy is attributed to its high nitrogen content and the presence of stacking faults.