Characterization of 7A04 Aluminum Alloy Corrosion under Atmosphere with Chloride Ions Using Electrochemical Techniques

The corrosion behavior of 7A04 aluminum alloy under marine atmosphere was studied. Salt spray test was used to simulate the marine atmospheric environment. Electrochemical impedance spectroscopy (EIS) and localized electrochemical impedance spectroscopy (LEIS) were employed to investigate the electrochemical behavior of 7A04 aluminum alloy after exposed in atmosphere containing Cl(-) for 288 h. The results show that the Cl(-) promots the atmospheric corrosion of the 7A04 aluminum alloy during the salt spray test. It is found that pitting appear in the initial stage of salt spray test and link each other to expand with the increase of test time. The EIS results show that electrochemical impedance value declines with the increase of test time. During the research period, the LEIS results indicate that the impedance value of 7A04 aluminum alloy's surface tends to decrease initially and then increase as the salt spray test time increased. Finally, the rate of atmospheric corrosion of 7A04 aluminum alloy is slowed down.