Microstructure and Tribological Properties of Lubricating-Reinforcing Laser Cladding Composite Coating with the Ti2SC-Ti2Ni Mosaic Structure Phase

Abstract

Lubricating-reinforcing composite coatings were successfully prepared on Ti6Al4V using laser-clad Ti6Al4V/Ni60/Ni-MoS2 mixed powders with different Ni-MoS2 contents (25, 35, and 45 wt.%), and their microstructure and tribological properties were studied. The reinforcing phase TiC, Ti2Ni, and the lubricating phase Ti2SC were in situ precipitated while Ti2SC and Ti2Ni formed a mosaic coherent structure within the above three coatings. In the 25 and 45 wt.% Ni-MoS2 coatings, the microstructure distribution uniformity of the coatings was not effectively improved by the Ti2SC-Ti2Ni mosaic structure phase due to the lower or higher content of Ti2SC. In the 35 wt.% Ni-MoS2 coating, the forming quality of the coating was the best due to an appropriate amount of the uniformly distributed Ti2SC-Ti2Ni mosaic structure phase. Furthermore, the microhardness of the coatings gradually decreased as the amount of Ni-MoS2 increased. In the 35 wt.% Ni-MoS2 coating, due to the uniformly and diffusely distributed Ti2SC-Ti2Ni mosaic structure phase, the stable lubricating-reinforcing mosaic structure transfer composite films were formed during the progress of the friction and wear tests, which led to the optimal worn surface evenness and quality, the anti-friction and the wear resistance properties compared with the Ti6Al4V, 25 and 45 wt.% Ni-MoS2 coating.