Validated numerical modeling of galvanic corrosion of zinc and aluminum coatings

A time-dependent finite element model was developed to simulate the corrosion of zinc and aluminum coatings, galvanically coupled to a mild steel substrate in deaerated 0.01 M H₂SO₄ electrolyte. The simulations of galvanic corrosion for each of the coatings were compared to experimental measurements of open circuit potential, and changes in coating geometry measured via surface profilometry. Good agreement between the model predictions and corrosion tests were observed initially for both coatings. However, in the case of the zinc coating, divergence was observed between the simulation and the corrosion test after approximately 40 min, due to a decrease in the reactivity of the zinc surface.