High-temperature wear behavior of HVOF sprayed, laser glazed, and laser cladded Stellite 6 coatings on stainless steel substrate

In this study, the Stellite 6 coating was applied on 316 stainless steel substrates through the high-velocity oxygen fuel method (ST-HVOF). Then, the laser-glazed sample (ST-Glazing) was deposited on the as-sprayed Stellite 6 coating using optimal conditions. Afterward, the Stellite 6 powder was optimized on the stainless-steel substrate by laser cladding process (ST-Clad) using 300 W and 5 mm/s of laser power and beam scanning speed, respectively. The microstructural characterization and phase analysis of ST-HVOF, ST-Clad, and ST-Glazing coatings were performed by field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) techniques. The microscopic observation results revealed that laser glazing significantly decreased the porosity of ST-HVOF (from about 2.3% to about 0.3%) and formed a dense coating with a uniform microstructure and strong adhesion to the substrate. Also, ST-Clad coating showed a porosity of 0.2% and a compact and uniform microstructure with a high-strength bonding to the substrate. Tribological evaluation of the coatings indicated a 67% and 58% increase in wear resistance of ST-Clad and ST-Glazing coatings compared to ST-HVOF coating, respectively. The high-temperature wear results suggested the following mechanisms for the studied coatings: plastic deformation mechanisms, wear adhesion, brittle fracture, and delamination.