Alkaline Electrodeposition of Ni-ZnO Nanocomposite Coatings: Effects of Pulse Electroplating Parameters

The effects of applied current density (1-10 A/dm(2)), pulse frequency (1-100 Hz) and duty cycle (10-75 %) on the morphology and microhardness of Ni and Ni-ZnO coatings, incorporation rate of ZnO nanoparticles, current efficiency and deposition rate were investigated. Ni-ZnO composites exhibited a nodular morphology. At low current densities, smooth and compact Ni-ZnO coatings were obtained. As the current density increased more gaps and defects appeared on the coatings surface. Maximum incorporation rate of 4.04 vol% was achieved at the current density of 10 A/dm(2). Presence of ZnO nanoparticles in the electrolyte improved the current efficiency of the process and deposition rate of the matrix. The microhardness values of the composites were considerably higher than those of the nickel coatings.