Analysis of the Cathodic Behavior of Aluminum in Natural Seawater by Surface Chemistry

摘要

The surface chemistry of aluminum in natural seawater was investigated by both theoretical and experimental study. Surface chemical analysis and electrochemistry were determined by use of Scanning Augar Microscopy and Scanning Potential Microprobe analysis. Postulated chemical mechanisms were examined theoretically via computer models. The major variables examined were pH, organic films, and copper concentration of the electrolyte. The role of temperature was studied less extensively. The results showed that significant concentrations of magnesium are present on the aluminum surface during corrosion in seawater. This supports independent data demonstrating that magnesium in the electrolyte plays an important role in the cathodic behavior of aluminum (Dexter, 1978). The theoretical analysis indicates that presence of magnesium on the aluminum oxide surface is most likely due to chemical adsorption. Other results show that the presence of copper on the aluminum surface is most likely due to a precipitation reaction and not an adsorption process.