Microstructure and wear characteristics of laser-clad Ni-based self-lubricating coating incorporating MoS2/Ag for use in high temperature

Nickel-based self-lubricating cladding containing Ag and MoS 2 was prepared on Ti6Al4V alloy using laser cladding. The microstructure, microhardness and wear behaviour were measured and analysed. The coating was mainly composed of Ti 2 Ni and TiNi as the matrix, and TiC and TiB 2 as the reinforcements. A new phase of Ti 2 SC was synthesized in situ in the coating, whereas Mo was consolidated in the matrix. The microhardness of the coating is greatly increased by in-situ generation of reinforcement phase and solution strengthening, with an average hardness of 823.6HV 0.2 , which is about 2–3 times that of the substrate. When the temperature increased to 600 °C, the coefficient of friction and wear rate of the coating decreased. The friction coefficient and the wear rate of the coating were greatly reduced at 800 °C. The wear rate of the coating decreased to 4.85 × 10 −6 mm 3 , which decreased by nearly an order of magnitude compared with the coating's wear rate at room temperature. The anti-friction effect of the lubricating phase not only counteracted the effect of the decreased hardness on the wear rate, but also played a more obvious anti-friction effect. In the high-temperature stage, MoO 3 and silver molybdate compounds produced by the tribological chemical reaction of wear surfaces could significantly improve the density of the enamel layer on the wear surface.