REACTION DISTRIBUTION IN A CORRODING PIT

An analysis of the reaction distribution over a corroding pit is prese nted. If the liquid-phase conductivity and the interfacial rate consta nts for the metal-dissolution reaction are known, the results of this secondary current distribution problem can be used to estimate the max imum rate of pit growth. The approach taken involves the conformal map ping of the pit geometry onto a new coordinate system; the finished tr ansformation is shown to remove the singularity at the pit edge and pr ovide a bounded region over which only a limited number of mesh points are required to perform accurate numerical analysis. Numerical calcul ations for the pit dissolution rate subject to linear and Tafel polari zation are fitted to simple expressions; as a consequence, the results of this work can be used without having to resort to numerical method s. For the linear polarization analysis, the results are generalized i n a manner that allows one to consider an arbitrary number of reaction s on the pit surface.