It is impossible to measure directly the current density (CD) distribution on the walls of real corrosion crevices or cracks. However, increasing numbers of workers are reporting in situ measurements of electrode potentials at various distances into a crevice or crack. Complex models are sometimes developed that calculate the potential distribution on the basis of various assumptions concerning how the CD on the walls depends on the potential and the solution composition.1,2 The predictions using different assumptions can then be tested against the measured potentials. However, the analysis presented below shows that it is often a simple matter to calculate the actual distribution of CD on the walls from the potential-depth data using a simple analytical transform. First, a general analysis is presented that is applicable to many crevice or crack geometries. Second, an example is given of an application to corrosion fatigue cracks.
The crack (or crevice) is...
