Effect of Cu content on microstructure evolution and tribological behaviors of Ni60 composite coatings on 45# steel by laser cladding

• The Ni60-Cu composite coatings were successfully prepared on 45# steel by laser cladding. • The addition of Cu is beneficial to improve the tribological properties of the composite coating. • The wear properties of45# steel superalloy have been significantly improved, and its wear mechanisms have been systematically and deeply studied. • The wear behaviors were investigated from the morphology of surface and wear affected zone respectively. • Different oxides are laminated and contributed different functions during the wear process. The Ni60-Cu composite coatings with varying Cu contents were fabricated by laser cladding technology. The effects of Cu addition on the microstructure, microhardness, and tribological behaviors were explored systematically. The results revealed that the composite coatings were primarily consisted by γ-Ni, FeNi 3 , Cr 7 C 3 , Ni 3 Si, Cu, and Fe-Ni-B. The addition of Cu was instrumental in enhance the tribological behavior at room temperature and 600 °C compared with the 45# steel substrate. Moreover, S2(Ni60-5 %Cu) coating showed the best compressive tribological properties, especially at 600 °C, it has the lowest friction coefficient of 0.267 and wear rate of 4.90 × 10 -5 mm 3 /N·m. The Cu played the role of tribo-transfer film and oxidation double-layered self-lubricant at room temperature and 600 °C, respectively.