The Influence of Passive Film Damage on Pitting Corrosion

Passive surface film protects metals from corrosive environments. Breakdown of the passive film initiates pitting corrosion and a lacy cover may form on top of the pit. The presence of the lacy cover affects the shape and size-evolution of the corrosion pit. We use a coupled corrosion-damage peridynamic model to simulate combined activation and diffusion-controlled pitting corrosion. Assuming a certain geometrical structure of the lacy cover (from non-existent to 50% coverage to undamaged film), we analyze the time-evolution of the shape and size of the pit. The model's results match closely those from experiments allowing us to conclude that the simple presence of the lacy cover is an important factor that controls/determines the shape evolution of the corrosion pit. (C) 2015 The Electrochemical Society.