Microstructure and tribological performance of sulfurizing layer prepared on the laser cladding Co-based alloy coating

Laser cladding of Co-based alloy coating owns excellent wear and corrosion resistances. The sulfides film fabricated by low temperature ion sulfurizing technique performs outstanding friction-reducing properties. In this study, the sulfides layer was successfully fabricated on the Co-based laser cladding coating by means of low temperature ion sulfurizing. The surface morphologies, microstructures and phase constituents were investigated by SEM, EDS, XRD and XPS. The results show that the surface of sulfurizing layer is loose and porous. The lubricant phases FeS and WS2 are detected in the sulfurizing composite layer. The thickness of the sulfurizing composite layer is about 3-4 mu m. Tribological properties were tested by a pin-on-disc tester, and the wear mechanisms were further analyzed. The friction results indicate that the friction coefficients and wear losses of the sulfurizing composite layer are decreased remarkably in contrast to the cladding coating under dry condition. The sulfides layer prepared on laser cladding coating shows excellent performance on wear and friction reduction. The lubricant phases of FeS and WS2 play an important role in improving the tribological performances of the sulfurizing composite layer.