Microstructure and tribological properties of self-lubricating antiwear composite coating on Ti6Al4V alloy

Self-lubricating antiwear composite coatings were fabricated on Ti6Al4V alloy by laser cladding. The dry sliding wear tests under various temperatures (ambient temperature, 350°C and 700°C) and normal loads (3, 6, 9 and 12 N) were accomplished, and the corresponding wear mechanisms were investigated. Results show that the composite coating presented lower friction coefficient at ambient temperature and 700°C, and the wear rate increased monotonously from ambient temperature to 700°C. The reasons are that the hard phases of TiC and TiWC₂ carbides enhance the wear capabilities at ambient temperature to 350°C. The CrS and Ti₂CS sulphides have friction reducing effect at 700°C. The friction coefficient decreased and the wear rate increased with the increasing of normal load. It is ascribed to the effects of the CrS and Ti₂CS sulphides at moderate normal load. It is implied that the tribological property of the composite coating showed the best at ambient temperature and moderate normal load.