Investigation on Nano‐Self‐Lubricant Coating Synthesized by Laser Cladding and Ion Sulfurization

Abstract

The composite processing between laser cladding and low temperature (300°C) ion sulfurization was applied to prepare wear resistant and self‐lubricating coating. The microstructure, morphology, phase composition, valence states, and wear resistance of the composite coating were investigated by scanning electron microscopy (SEM), atomic force microscope (AFM), X‐ray diffraction (XRD), X‐ray photoelectron spectroscope (XPS), and friction and wear apparatus. The results indicate that the laser cladding Ni‐based coatings and the maximum hardness of 46.5 HRC were obtained when the percent of pure W powder was 10%, composed of columnar dendrites crystals and ultrafine dendritic structure. After ion sulfurization at 300°C for 4 h, the loose and porous composite coating is formed with nanograins and the granularity of all grains is less than 100 nm, which consists of γ‐(Fe, Ni), M23C6 carbides, FeS, FeS2, and WS2. Furthermore, the wear resistance of the composite coating is better than the laser cladding Ni55 + 10%W coating, and the friction coefficient and mass losses under the conditions of dry and oil lubrication are lower than those of laser cladding Ni55 + 10%W coating.