On the rate determining step of cathodic delamination of delamination-resistant organic coatings

Cation transport from defect site to delamination front and oxygen reduction at the polymer/metal interface are the two processes that are proposed to control the kinetics of cathodic delamination. However, it was suggested that instead the ingress of cations at the delamination front controls the kinetics, shown first for weak coatings. Here, the validation also for resistant industrial coatings is reported. It is also shown that cations mainly serve for pulling down the potential at the front while the electron flow supporting ongoing oxygen reduction at the delaminated interface is compensated by hydroxyl ion migration towards the defect.