Application of Gel Electrolytes to Validate Transient Models of Galvanic Corrosion Phenomenon

The present work focuses on studying the acidity generated in the electrolyte during the galvanic corrosion of an aluminum alloy (AA) in contact with carbon steel (CS). A bare galvanic system exposed to a thin NaCl electrolyte has been considered. In this work, a mathematical model solved by the finite element method (FEM) is presented. It considers both electrochemical and aluminum hydrolysis reactions in the electrolyte solution. The model allows predicting the propagation of acidic pH fronts along the AA surface. Subsequently, the results obtained were validated by employing an innovative experimental technique using agar films doped with a pH indicator. The experimentally measured acid fronts show a similar trend to the numerical predictions and have a reasonable correlation in the first few minutes of the corrosion process.