Surface modification of tungsten carbide cobalt by electrical discharge coating with quarry dust suspension

This study explores the feasibility of reusing waste quarry dust as a coating material for surface modification of tungsten carbide cobalt (WC-Co) using electrical discharge coating (EDC). The main objective is to investigate the effect of quarry dust suspension with different concentrations (0–40 g/l) on the characteristics of coated surface such as coating layer thickness, coating element composition and chemical compound, surface morphology, surface roughness and Vickers micro-hardness. Before the EDC process, characterisation of the raw quarry dust was conducted through scanning electron microscopy, X-ray fluorescence and particle size analyser. The results showed that the coating layer thickness was strongly affected by the quarry dust concentration. The formation of hard carbides (SiC, Mg₂C₃, Fe₂C and CaC₂) and oxide phases (SiO₂, Al₂O₃, Fe₂O₃, CaO, CoO and ZnO) in the coated layer due to material migration was confirmed through X-ray diffraction analysis. Vickers micro-hardness of the coated surface was improved significantly with the addition of quarry dust. The best surface finish without micropores and microcracks was obtained using a quarry dust concentration of 10 g/l. These results demonstrated the capability of recycling quarry dust as an environmentally friendly coating material for surface modification.