Electrodeposition of Ni-Mo/Al2O3 nano-composite coatings at various deposition current densities

In this study, the effect of deposition current density on the characteristics of nickel-molybdenum/alumina coatings processed by an electrodeposition method was investigated. Morphological, elemental and phase evaluations were conducted on the deposited coatings by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction, respectively. Furthermore, the hardness, wear and corrosion behaviors of the prepared coatings were measured. The results showed that the coatings prepared at high current densities, typically at 8 A/dm(2), exhibit a porous and rough morphology. Also, the contents of molybdenum and alumina deposited at high current densities are reduced, thus increasing the crystallite size and deteriorating the mechanical properties and corrosion resistance. In this regard, the optimum current density to meet the most desirable properties was found to be 4 A/dm(2).