Monitoring of Initial Stages of Atmospheric Zinc Corrosion in Simulated Acid Rain Solution under Wet/Dry Cyclic Conditions

Abstract

Abstract The exposure of zinc samples in simulated acid rain solution (SARS) was investigated under periodic wet/dry conditions using an alternating current (AC) impedance technique. The influence of relative humidity (RH), temperature, and surface inclination on the atmospheric corrosion of zinc is described. The polarization resistance reciprocal (1/Rp) decreases rapidly during the initial stages and slowly attains a steady state as the overall exposure time progresses. The experiment result shows a pronounced dependence reciprocal polarization resistance on RH. Two main components were identified in the corrosion products on zinc surfaces, namely hydrozincite (Zn5[OH]6[CO3]2) and hydrated zinc hydroxysulfate (Zn4SO4[OH]6·nH2O [n = 1, 2 and 3]). Exposure in the presence of carbonate anions gives rise to more protective corrosion products than it does in a nitrate anion solution.