Current-carrying tribological performance of CrB₂/Cu composite coating prepared by laser cladding technology

To repair and extend the service life of mobile-contact parts, laser cladding technology was applied to prepare CrB₂/Cu coating on Cu–Cr alloy substrate, which was simulated as actual servicing parts, and the current-carrying friction property, including that friction coefficient, wear rate as well as current-carrying efficiency were studied. Results show that most of the CrB₂ particles retain while some decompose into CrB_x phases during the laser cladding process. With the increase of electric current, the average friction coefficient of CrB₂/Cu coating grows first followed by going down. In comparison to the CrB₂/Cu coating, the wear rate and average friction coefficient of QCr0.5 substrate always grow with increasing electric current values. When the current is 20A, the COF and wear rate of composite coating are about 0.737 and 1.37 × 10^–4 mm³/N•m, which are about 21% and 79% of that of QCr0.5 alloy, respectively, and the major wear mechanism of CrB₂/Cu coating is the adhesive wear. Moreover, the CrB₂/Cu composite coating has low friction coefficient, low wear rate and high current-carrying efficiency under high electric currents, as a consequence, the CrB₂/Cu coating has better current-carrying friction and wear performance under high current conditions.