Copper-rich Cu–Zn alloy coatings prepared by electrodeposition from glutamate complex electrolyte: Morphology, structure, microhardness and electrochemical studies

Abstract

In the present work, glutamate ions were applying as a complexing agent in codeposition of Cu-Zn alloy coatings from a non-cyanide acidic sulfate bath at room temperature. The effect of Cu2+/Zn2+ concentration ratios as well as the glutamate ion concentrations on the morphology, structure, and microhardness of the alloy coatings was studied. Electrochemical analyses were implemented using cyclic voltammetry and anodic linear stripping voltammetry. It was found that glutamate ions decrease cathodic overpotential for the reduction of Zn2+ ions and enhances cathodic overpotential for the reduction of Cu2+ ions. Consequently, the simultaneous codeposition of Zn2+ and Cu2+ ions were facilitated and copper-rich Cu–Zn alloy coating was achieved. Characterization of Cu-Zn alloy coatings was carried out using SEM and XRD. The Cu-Zn alloy deposited from the glutamate complex bath consisted mainly of one phase α-CuZn. The morphology of Cu-Zn alloy significantly depends on the Cu2+/Zn2+ concentration ratios, glutamate ion concentrations as well as on the operating conditions as shown by SEM investigation. Moreover, Cu-Zn alloy coating deposited from these baths possesses microhardness ranged from 115 to 250 kg mm−2 depending on the bath composition and the operating conditions.