Electrochemical performance of initial corrosion of 7A04 aluminium alloy in marine atmosphere

The initial corrosion of 7A04 aluminium alloy in marine atmosphere was studied. Salt fog test was used to simulate the marine atmospheric environment. Electrochemical impedance spectroscopy (EIS) and scanning Kelvin probe (SKP) were employed to investigate the electrochemical behavior of 7A04 aluminium alloy in marine atmosphere. The results show that the Cl^- can accelerate the atmospheric corrosion of 7A04 aluminium alloy during the beginning exposure period. Pittings appear in the initial stage of salt fog test and link each other to expand with prolonging test time. The electrochemical impedance magnitude declines during the corrosion test. The SKP results indicate that the anodic and cathodic areas change constantly with distinct character of localized corrosion. When the corrosion process continues, the surface potential of 7A04 aluminium alloy increases, while anodic and cathodic area distinguish evidently from each other. Atmospheric corrosion of 7A04 aluminium alloy is promoted during the initial stage in marine air.