New diffusive interface model for pitting corrosion

Abstract

In this paper, a diffusive interface model for pitting corrosion is proposed, which can be used to simulate diffusion- and activation-controlled pitting corrosion with the pit morphologies and the distribution of metal cation concentration. The diffusive interface equation is derived from the general interface advection-like equation coupled with the description of the normal velocity of the moving pitting boundary from the sharp interface model. The corrosion rate is expressed in an explicit way through the diffusion field in the diffusion-controlled regime, and the activation-controlled corrosion is expressed by introducing the interface kinetic parameter, which greatly simplifies the model. The curvature effect can be subtracted back out directly by introducing a counter term. Predicted results from numerical simulations are compared with the analytical solution to determine numerical parameter in one-dimensional pencil electrode test. The effect of local curvature on simulated semicircle corrosion is discussed. Then, the application scenarios of the model including electropolishing, single and multiple corrosion, corrosion with composite materials are presented.