Kinetics of Corrosion Film Growth on Copper in Neutral Chloride Solutions Containing Small Concentrations of Sulfide

The corrosion behavior of oxygen-free copper in an anoxic 0.1 M solution was studied using electrochemical impedance spectroscopy, scanning electron microscopy equipped with a focused ion beam, X-ray photoelectron spectroscopy and micro X-ray diffraction. The corrosion film grew as a coherent, compact crystalline layer with a nonuniform thickness. The growth kinetics obeyed a parabolic law consistent with control by a diffusion process. Once a coherent layer was established, film growth kinetics appeared to be controlled by ion diffusion through the film. At shorter times before a coherent film was established, diffusion in solution exhibited a considerable influence on the growth rate.