Study of potential activation phenomenon and initial process of the metal electrodeposition

The potential-time curves under constant current and cyclic voltammetry curves were measured, and the potential activation process of copper plating on iron substrate in cyanide electrolyte was shown. The initial process of pyrophosphate copper plating on the iron electrode was studied. The results show that deposition potential of copper is positive and copper deposits on the inactive surface of electrode. The bond intensity of plating layer is very bad. By using Ar ion sputtering and X-ray photoelectron spectroscopy, the oxygen contents between the copper plating layer and iron substrate were examined and the existence of oxygen layer was proved. Through adding assistant complexing agent and controlling initial current density, cathodic polarization was intensified in cyanide-free electrolyte. When the deposition potential of copper is less than activation potential of the iron substrate, the potential activation process was shown. The bond intensity of the plating layer is close to that of cyanide copper plating.