AC impedance study on the atmospheric corrosion of aluminum under periodic wet–dry conditions

Abstract

The atmospheric corrosion of aluminum under periodic wet–dry conditions has been studied in simulated acid rain solution (SARS). Dependence of atmospheric corrosion of Al on temperature, surface inclination, RH and state of surface has been investigated in a laboratory in terms of polarization resistance, solution conductance and corrosion product characterization. An increase in temperature leads to an acceleration of the corrosion process. The average of reciprocal of polarization resistance per cycle (ARPR) of aluminum in a 0.05 M NaCl solution increases to a maximum value, due to pitting corrosion. The corrosion rate of aluminum decreases rapidly at the initial stages of exposure to ammonium sulfate solution then decreases slowly while the time of exposure progresses. The atmospheric corrosion of a sample exposed horizontally is higher than that of a sample inclined at 30°.