Impact of rare earth compounds on corrosion of aluminum alloy (AA6061) in the marine water environment

Abstract The impact of rare earth compounds (CeCl3 and Ce2(SO4)3) on the corrosion inhibition of aluminum alloy (AA6061) in 3.5% NaCl solution was elucidated using polarization, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS) and complemented with EDX and SEM examination. The addition of either CeCl3 or Ce2(SO4)3 to the blank chloride solution, decreases the corrosion current and causes a widening of the passive potential range between corrosion potential (Ecorr) and pitting potential (Epit). The data confirmed that CeCl3 and Ce2(SO4)3 act as corrosion inhibitors. It was found that the inhibition performance of Ce2(SO4)3 are higher than that of CeCl3. In the presence of Ce2(SO4)3 and CeCl3, the AA6061 surface is well protected, in which the surface of AA6061 was smoother and the corroded areas obviously diminished. The results suggest that the existence of Ce2O3/Ce(OH)3 conversion coat on the electrode surface enhances the charge and mass barrier leading to the reduction in corrosion rates of the AA6061 alloy.