Theory and technology for electroplating a rose golden Cu-Zn-Sn alloy using a disodium ethylenediamine tetraacetate system

A non-cyanide rose golden electroplating system was investigated in this work. The electroplated layer of Cu-Zn-Sn alloy was also investigated using a disodium ethylenediamine tetraacetate (EDTA2Na) system, in which CuSO(4)5H(2)O, ZnSO(4)7H(2)O and Na(2)SnO(3)3H(2)O were the main salts. EDTA2Na acted as a complexing agent. Finally, NaOH acted as a buffering agent in the electroplating solution. The effects of different electroplating solutions on colour, micro-topography, composition and phase structure of the electroplated layer was analysed by photo analysis, SEM, EDS and XRD. Meanwhile, different electroplating solutions were analysed and compared by electrochemical analysis and UV-Vis, FTIR and NMR spectroscopy. A rose golden electroplated layer of Cu-Zn-Sn alloy could be obtained by adjusting the amount of the main salts. The composition of the electroplated layer was 98.81% Cu, 0.77% Zn and 0.42% Sn. Moreover, the electroplated layer was composed of regular 50-100nm particles. The composition of the ternary alloy-electroplated layer was Cu, Cu5Zn8 and Cu10Sn3 phase. At the same time, the cathode only had a single deposition peak at -1.22V by electrochemical analysis of the electroplating solution. UV, IR and NMR analyses show that a chelate was formed with EDTA2Na and metal ions in an alkaline environment. These results may provide a theoretical guidance for a new technology for Cu-Zn-Sn alloy electrodeposition. [GRAPHICS] .