Current and Potential Distributions for a Freely Corroding Disk Electrode

This Demonstration shows the process of corrosion in a disk-shaped metal electrode. The potential distribution (blue curves) and the current distribution (red curves) are shown on the left for the vertical distance represented by the red point. A contour plot of the equipotentials is shown on the right. You can vary the radius of the disk-shaped electrode (black bar) to investigate the affect of the size of the electrode on the corrosion.


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The potential distribution for various vertical distances from the surface is shown on the left. For large distances, the potential differences are small; it is not possible to detect local processes (snapshot 1). At the near-surface distance, the potential distribution is more pronounced: a maximum at the center of the disk electrode and smaller values along the side of the electrode (snapshot 2).
Current flow is at a maximum at the electrode/insulator interface. The asymptotic behavior for an interface of results from the fact that the potential in the solution immediately adjacent to the electrode surface is parallel to the electrode. Thus, the current distribution is a maximum at the electrode/insulator interface and a minimum at the center of the electrode.
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