Corrosion and Hardness Characteristics of Laser Surface-Modified Ti6Al4V/Zr+TiC and Ti6Al4V/Ti+TiC Composites

The corrosion and hardness characteristics of laser cladded Ti6Al4V alloy with and without coaxial nozzle with respect to variable laser power was investigated. The electrochemical behaviour of pure Ti-6Al-4V alloy coated with Zr-Ti and Ti-TiC ceramic powders were studied with respect to open circuit potentiodynamic polarization test. Passivation tendency of Ti-6Al-4V alloy as a result of different compositions of Zr and TiC reinforcement additions was examined at room temperature in .1 M H2SO4 + 3.75% NaCl solution. It was observed that modified MMCs 70%Zr+30% TiC without coaxial nozzle at 750 W gave higher hardness value as compared with the same ratio in composition at 1.4 kW. Experimental results indicated that the corrosion rate of the developed composites decreased significantly with addition of ceramic powder admixture. The result obtained from the polarization behavior show a decrease in polarization resistance with decrease in zirconium content and increase in composition of TiC because of the carbide phase. While the open-circuit potential for the alloy was found to reduce with time due to oxide film thickening on the metal surface.