Study on the behavior of Zn–Fe alloy electroplating

The electroplating behavior of Zn, Fe and Zn–Fe alloy onto copper from light acid chloride solutions (LACS, pH 3.07 containing H3BO3, Na2C6H5O7·2H2O and different amounts of Zn2+ and Fe2+) was investigated by means of cyclic voltammetry and the steady-state polarization technique. It was found that, in the experimental conditions, during the Zn–Fe alloy formation no underpotential deposition (upd) was observed, and the deposition of Zn–Fe followed the mechanism of three-dimensional (3-D) nucleation and subsequent grain growth. The Zn2+ ions in the electrolyte inhibit the deposition of Fe, while Fe2+ ions promote the deposition of Zn. It was also found experimentally that the co-deposition of Zn and Fe behaved anomalously, and the result was interpreted theoretically in the light of quantum chemistry.