Influence of the sulphuric acid concentration on the kinetics and mechanism of silver ion cementation on copper

Abstract

The effect of sulphuric acid concentration on the kinetics of silver ion cementation on copper in the electrolyte containing 0.5 M CuSO 4 was investigated using a rotating cylinder system. The morphology of the silver deposit cemented in the presence and absence of oxygen was studied at 25 °C. Additionally, the influence of H + ion concentration on the mechanism of cementation, proposed by Khudenko et al., was verified. It was found that various concentrations of sulphuric acid neither change the kinetics of cementation nor the mechanism of process conducted in the presence or absence of oxygen in the system. The increasing concentration of H + ion does not enhance the silver cementation on copper. The decreasing concentration of sulphuric acid in the electrolyte used in the cementation process promotes only a deposition of less-adhesive silver cement on copper. This study showed clearly that the Khudenko's mechanism of cementation is highly doubtful. Moreover, results proved that H + ions are not involved in the mechanism of the process at all. The mechanism of silver ion cementation on copper in acidic copper sulphate solutions is strongly determined by the presence of oxygen in the system.