Electrochemical characterization of metastable pitting of 3003 aluminum alloy in ethylene glycol-water solution

The corrosion and electrochemical behavior of 3003 aluminum alloy in ethylene glycol-water solution were investigated by electrochemical techniques. It is found that the oxide film formed on aluminum depends on the dissolved oxygen in the solution. In the presence of oxygen, a layer of aluminum oxide film forms on the aluminum surface to protect the substrate from corrosion. In the absence of oxygen, the film formed is mainly aluminum-alcohol film that is less compact and less resistant to corrosion. The aluminum oxide film and aluminum-alcohol film have the different susceptibilities to chloride ion attack for pit initiation. There is a higher pitting susceptibility for aluminum oxide-covered electrode. The increase in temperature decreases the resistance of aluminum electrode to corrosion reaction. However, the resistance to pitting corrosion increases.