Effect of probe sonication and sodium hexametaphosphate on the microhardness and wear behavior of electrodeposited Ni-SiC composite coating

Electrodeposited Ni-SiC composite coating is the most widely used engineering coating. Ni-SiC coating is bestowed with higher wear resistance and microhardness compared to plain nickel. In this study, the feasibility of using sodium hexametaphosphate as a dispersant in the electrodeposition of Ni-SiC composite coating has been investigated. The effect of sodium hexametaphosphate and probe sonication on the microhardness, microstructure and wear resistance of the electrodeposited Ni-SiC composite coating has been studied. X-ray photoelectron spectroscopy analysis of the coatings showed the absence of Na and P elements from sodium hexametaphosphate in the bath. Ni-SiC coating deposited using probe sonication followed by the addition of sodium hexametaphosphate exhibited microhardness as high as 680 HK. The microstructure of the coatings varied with probe sonication and SHMP addition and Ni-SiC-PS-SHMP coating possessed lowest roughness. This study has revealed that a synergistic combination of probe sonication of the electrolyte bath containing particles followed by sodium hexametaphosphate addition enhances the co-deposition of finer SiC particles and thereby enhances the coating properties like microhardness and wear resistance.