Pitting corrosion of copper in chloride solutions

Abstract

The pitting corrosion of copper in chloride solution has been studied using potentiostatic polarisation and surface analysis techniques. X‐ray photoelectron spectroscopy (XPS) results enabled conclusions to be drawn about the nature of the film formed in different chloride concentrations. In dilute chloride solutions (C≤10−3 M), XPS proved the existence of Cu2O film on the copper surface. It was found that, depending on the chloride content, pitting of copper was evident only after the formation of a protective film of Cu2O. A current‐time trend plot showed the onset of fluctuations, which were dependent on the NaCl content. On the other hand, introduction of O2 into the solution during prepolarisation time period increased the current value of the fluctuations at the same concentration of NaCl in comparison with the freely aerated solution. These results, together with the surface analysis, confirm the role of chloride ion on the mechanism of pitting attack on copper metal.