Study of simulated disbonded polymer film on Zn-Al alloy coated reinforcing steel rebars

A cell was made to model disbonded regions of a polymeric coating on 98Zn/2Al alloy used to protect rebar of reinforced concrete. A crevice electrode was designed to make a tight crevice with a gap thickness less than 0.03 mm. Experiments were conducted with the crevice facing downward in 1 M sodium hydroxide. The results for thinner crevices indicated a general trend of a larger potential rise of around 1 V. A dissolution/passivation mechanism was proposed to occur inside the crevice. A general pseudo-passivation was concluded to occur inside the crevice that protects the 98Zn/2Al alloy from corrosion.