Relation between plating overpotential and porosity of thin nickel electrolytic coatings

The relation between plating overpotential and porosity of thin Ni electrolytic coatings (0.2 mu m) was investigated. The porosity of Ni coatings was shown to be dependent on coating structure, which is determined by the plating overpotential. A lower porosity can be achieved by using a relatively high plating overpotential resulting in the deposition of Ni coatings with fine grains. A relation between the through-coating porosity of thin Ni coatings and the activation overpotential was identified. At plating current densities approaching the limiting current density, the porosity tends to increase due to a mass transport effect on the coating thickness distribution along the substrate surface.