Study of the effect of Triethanolamine as a chelating agent in the simultaneous electrodeposition of copper and zinc from non-cyanide electrolytes

• Brass electroplating was successfully performed using non-cyanide solutions.
• Brass electroplating has been conducted in Triethanolamine (TEA) baths.
• Electrodeposited coating of Cu–Zn alloy have been confirmed.
• TEA reduces the overpotential for Zn2+ reduction enabling the alloy deposition.
• Cu–Zn film composition can be modified by optimization the TEA concentration.

Cu–Zn coatings were obtained from cyanide-free electrolytes containing CuSO4·5H2O, ZnSO4·7H2O, Triethanolamine (TEA) and NaOH with different cation concentrations. Electrochemical analyses were performed using cyclic voltammetry and potentiostatic polarization in order to analyze the effect of TEA as a complexing agent of Cu2+ and Zn2+ ions and its influence on the composition of the electrodeposited films. It was observed that TEA diminishes cathodic overpotential for the reduction of Zn2+ ions and increases cathodic overpotential for the reduction of Cu2+ ions. As a consequence, the simultaneous electrodeposition of Zn2+ and Cu2+ ions was facilitated and a brass (Cu–Zn alloy) coating was obtained from non-cyanide solutions. The composition and appearance of the Cu–Zn film can be modified by optimization of the cathodic current density and the concentration of TEA, Cu and Zn in the electrolyte. The ray-X results show a Cu–Zn coating with a content of Zn > 25% from a non-cyanide electrolyte as an alloy of α-CuZnα-CuZn. From the results of this work, a promissory and environmentally friendly alternative to the electroplating bath can be developed, from which a brass alloy can be electrodeposited using a non-cyanide electrolyte.