The effect of chloride ions concentration on the passive behavior of AA6061 aluminum alloy in a borate buffer solution (0.3 M H3BO3 + 0.01 M Na2B4O7, pH=7.15) has been investigated by using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Potentiodynamic polarization curves indicate that chloride ions concentration narrowed passivation region for AA6061 aluminum alloy. Also, these polarization curves revealed that increasing chloride ions concentration leads to decrease the pitting potential of AA6061 aluminum alloy. EIS tests showed that the passive films formed in chloride-free solution are most stable, and that formed in chloride-containing solution are unstable. Also, EIS tests demonstrated that the charge transfer resistance of AA6061 aluminum alloy decreases by increasing the concentration of chloride ions.
