Corrosion behavior of anodized AA-6060 depending on the anodizing bath aging

The present work is concerned with the corrosion behavior of anodized AA-6060 in chloride containing solutions. The anodic layers were produced with identical anodizing parameters but in an anodizing bath at different stages of bath aging or the time of use, respectively. The bath aging was monitored by the conductivity and was related to the consumed charge. The oxide layers were characterized by scanning electron microscopy (SEM)/electron dispersive x-ray spectroscopy (EDX) and X-ray fluorescence analysis. The corrosion behavior was characterized by a combination of electrochemical measurements (linear sweep voltammetry and electrochemical impedance spectroscopy) and corrosion tests (droplet and salt spray tests). It is shown in this paper that the kinetics of oxide formation, as well as the oxide composition, changes with ongoing bath aging. The corrosion protection of the anodic layers strictly depends on the time of use of the anodizing bath and decreases continuously with ongoing bath aging.