Pulse electrodeposition and corrosion properties of Ni-Si3N 4 nanocomposite coatings

Abstract

The development of modern technology requires metallic materials with better surface properties. In the present investigation; Si3N4-reinforced nickel nanocomposite coatings were deposited on a mild steel substrate using pulse current electrodeposition process employing a nickel acetate bath. Surface morphology, composition, microstructure and crystal orientation of Ni and Ni-Si3N4 nanocomposite coatings were investigated by scanning electron microscope, energy dispersive X-ray spectroscopy and X-ray diffraction analysis, respectively. The effect of incorporation of Si3N4 particles in the Ni nanocomposite coating on the micr hardness, corrosion behaviour has been evaluated. Smooth composite deposits containing well-distributed silicon nitride particles were obtained and the crystal grains on the surface of Ni-Si3N4 composite coating are compact. The crystallite structure was face centred cubic ( fcc) for electrodeposited nickel and Ni-Si3N4 nanocomposite coatings. The micro hardness of the composite coatings (720 HV) was higher than that of pure nickel (310 HV) due to dispersion-strengthening and matrix grain refining and increased with the increase of incorporated Si3N4 particle content. The corrosion potential (Ecorr) in the case of Ni-Si3N4 nanocomposite had shown a negative shift, confirming the cathodic protective nature of the coating. ©Indian Academy of Sciences.