Friction and wear characteristics of laser-clad nano-lubricant coating

Abstract

The friction and wear characteristics of nickel-based self-solid lubricant coating produced by a Nd: YAG Laser was studied in this paper. The change tendency of some elements and surface topography of the coating was analyzed by SEM and EDS. It was found that a large amount of white particles and submicron pores are distributed in the Ni-based alloy solid solution matrix. For the laser-clad Ni60–10%BN–5%CaF2 coating at the output power of 380W, the microstructure in the upper and interface regions is dendrites and small amount massive compound, which is fine and homogeneous. EDS analysis indicate that hexagonal BN lubricant has been fused into the coating in the laser cladding procedure. Elements of Cr, Ni and Fe which comes form self-fluxing powders Ni60 change obviously. Cladding coating and the substrate is good metallurgical combine. The friction and wear characteristics of the coating which contain solid-phase lubricant (h-BN) and non-lubricant were tested. The results show that the friction coefficients of Ni60–10%BN–5%CaF2 and Ni60 coatings are stable about 0.5 and 0.63, respectively, when friction pair rotational speed is 2m/s and loading is 20N under room temperature. The corresponding friction coefficients have no obvious change during the friction pair rotational speed or loading changes. While the friction coefficient of the laser-clad Ni60–10%BN–5%CaF2 is decreased sharply to between 0.35 and 0.45 during friction pair rotational speed is 2m/s and loading is 40N under 400℃, which indicates that hexagonal BN lubricant in the laser cladding coating plays a role of anti-friction under heavy loading.