Numerical Study of Aluminum Pitting Corrosion Using a Two- Dimensional Multi-Species Transport Model

Pitting corrosion is a local degradation of the passivation layer formed on the metal surface. It is considered more dangerous than uniform corrosion because the cavities fill with corrosion products and are thus difficult to detect. Considering the complexity of the phenomena involved in the pitting corrosion process, numerical simulation based on the finite element method is a timely tool to overcome the difficulties and limitations of experimental studies. In this study, a two-dimensional numerical model has been developed to simulate the behavior of aluminum against pitting corrosion in a sodium chloride solution. This simulation is based on the resolution of the Nernst-Planck equation describing the mass transport phenomena and the reactions of chemical species in solution. The results show that the local chemistry of the pit has an effect on the evolution of pitting corrosion. Furthermore, the pit geometrical shape influences the corrosion behavior due to the role of the local chemistry in solution and the electric field at the metal/solution interface.