Electrodeposition behavior of Zn-Ni alloys produced from sulfate solutions at high current densities

Abstract

The electrodeposition behavior of Zn-Ni alloys produced from acidic sulfate solutions was investigated from partial polarization curves obtained during alloy electrodeposition. At the current density at which the co-deposition of Zn-Ni alloys produced anomalous results, we found that Zn deposition is polarized and is affected by the bath Zn concentration and flow rate. This indicates that Zn deposition is controlled by diffusion at high current densities. Under the conditions for increased Zn deposition, Ni deposition was not suppressed even in the region of anomalous co-deposition. With a low pH bath, the Ni concentration in the deposit did not increase under a high current density because of strong suppression of Ni deposition under the low pH condition.