Effects of surface composite structure with micro-grooves and Sn-Ag-Cu on reducing friction and wear of Ni3Al alloys

To overcome the failure of liquid lubricants in the fields of energy equipment and aerospace industry, the synergistic effect of surface micro-textures and solid lubricants is a promising approach to solve the problem. This paper sought to improve the tribological performance by designing the surface composite structure on a Ni3Al metal matrix, in which surface micro-textures were filled by solid lubricants 96.5Sn-3.0Ag-0.5Cu alloys (SAC305). Dry reciprocating sliding tests were conducted as a basic assessment for synergistic lubricating analysis of surface composite structure. Results showed that the composite structure with the surface texture density of 28% and deposited SAC305 alloys had the lowest friction coefficient (0.39) and mean wear volume (0.37mm(3)) in comparison with other prepared samples. The reasons of the surface composite structure reducing the friction and wear of Ni3Al alloys mainly are that SAC305 alloys deposited into surface micro-grooves can improve the capacities of load-carrying and resistance to plastic deformation of the contact surface, and a SAC305 lubricating film formed on contact interface can reduce the direct contact between the counterpart ball and Ni3Al matrix. The Ni3Sn2 phase generated at the interface under the roles of friction behavior, which acts as a transiting layer to connect Ni3Al matrix and SAC305 alloys, promotes the formation of the self-adaptive friction structure. Moreover, the interconnection between the dynamic change of the friction coefficient and a lubricating film formed on contact interface was established, which could be used to evaluate the wear characteristics applied in the engineering field under harsh conditions.