Effect of current density on deposition process and properties of nanocrystalline Ni–Co–W alloy coatings

The nanostructure Ni–Co–W alloy coatings were electrodeposited onto a copper substrate using different applied current densities, in a modified Watts-type bath. The coatings were single-phase solid solutions with average grain sizes about 6–11 nm, calculated from X-ray diffraction patterns using the Scherrer equation. EIS results showed that the adsorption and reduction of W-containing ion complexes dominated at all applied current densities. However, the diffusion of the ion complexes reached to a limitation at higher current densities. The W and Co contents of the coatings decreased with an increase in the applied current density. A homogeneous nodular surface morphology was obtained at all current densities. The coatings produced at low current densities, containing higher amount of alloying elements, showed lower corrosion resistance.