A model of ionic current densities in the vicinity of a corroding disk-shaped region

The scanning vibrating electrode technique (SVET) permits the measurement of ionic corrosion current densities in a uniform electrolyte solution adjacent to an anodic region in a corroding metal sheet. A credible model for such a corrosion experiment envisages a disk-shaped anode embedded in an infinite coplanar sheet of more noble metal, serving as the cathode. If ohmic polarization governs the corrosion rate, then Laplace's equation holds in the steady state. Two independent, but different, solutions of this equation exist, both based on the premise that the two metallic regions have distinct uniform electrical potentials. In this communication, we show these two solutions to be equivalent and thereby predictions are made about the ionic current densities at points in solution near the corrosion site. These predictions are found to be qualitatively similar to reported experimental findings. (C) 2001 Elsevier Science B.V. All rights reserved.