Effect of cerium oxide addition on microstructure, microhardness and wear rate of the composite coating fabricated on titanium alloy

In this study, a defect free hard and wear resistant coating has been fabricated using pre-placed powder TIG cladding method on Ti-6Al-4V substrate. The impact of different percentage of cerium oxide on surface mechanical and tribological behaviour of the coating has been investigated. FESEM images showed surface irregularities and micro-voids in the coating that does not have cerium oxide. Short and long needle type microstructure was observed for the sample not containing cerium oxide while cage like pattern is observed for the rest samples. The equiaxial and short dendrites are grown between the cage like pattern, which enhances the mechanical and tribological properties of the fabricated coating. Nickel titanium, tungsten carbide, titanium dioxide, aluminium nickel titanium, and aluminium cerium nitride are the phases formed within the coating. Microhardness of the coating ranging from 700 to 900 HV0.5, whereas coefficient of friction is reduced to 0.15, which is much better than Ti-6Al-4V substrate