An electrochemical model was developed to predict the transient distribution of species generated during corrosion of a carbon steel/AA7075 aluminum alloy galvanic couple. Both metals were set under a confined electrolyte layer of thickness 50 μm containing ten interacting chemical species. The model was solved by the finite element method. The main contribution of the model is the use of an extra source term within some governing equations to avoid solving for the O concentration in extremely thin domains. The solution is rendered as top-view instead of the usual cross-sectional one. The whole model provides both a light computational code and a robust approach to the phenomenon under study. Transient experimental pH measurements were achieved with the help of an innovative setup implemented for micrometric electrolyte layers. The experimental and predicted pH fronts had an acceptable level of agreement.

This work has been financed by the UNAM-DGAPA-PAPIIT program (TA100318). A.R.G. acknowledges the Conacyt scholarship. Authors acknowledge the support of LIMO and PND laboratories from PUNTA-UNAM.

Peer Reviewed