Influence of surfactant on the properties of Ni-P-nano ZnO composite coating

Electroless Ni-P composite coating was applied to the mild steel substrate with the co-deposition of ZnO nanoparticles at the optimum concentration in electroless bath. Microhardness, corrosion resistance and deposition rate of Ni-P-ZnO composite coatings have been investigated by the addition of anionic, cationic, non-ionic surfactants into the electroless bath. Surface, structure, morphology and chemical composition details were studied by x-ray diffraction (XRD), scanning electron microscopy (SEM) and EDS analysis. Corrosion resistance and microhardness of the coatings were measured by using potentiodynamic polarization technique and Vickers microhardness tester. Results reveal that ZnO nanoparticles observed in the coating formed in the presence of anionic surfactant yields highest microhardness. The reinforcement of ZnO nanoparticles improves the resistance to corrosion of the Ni-P coatings by filling micro pores present on the surface. It results decreasing the metallic prone area to corrosion attack.