A Comparative Study on the Electrochemical Corrosion Behavior of Microcrystalline and Nanocrystalline Aluminum in Natural Seawater

摘要

In this study, we compared the electrochemical corrosion behavior of a newly fabricatednanocrystalline pure aluminum to another microcrystalline aluminum using various electrochemicaltechniques in natural Arabian Gulf seawater. The nanocrystalline Al was fabricated using mechanicalalloying technique. Cyclic potentiodynamic polarization showed that microcrystalline has lowercorrosion current and corrosion rate with higher polarization resistance compared to thenanocrystalline Al. The change of current with time at -550 mV vs. Ag/AgCl revealed that thenanocrystalline Al had higher absolute currents. The scanning electron microscopy images showed thatnanocrystalline Al surface was more corroding under the aggressiveness action of the seawater and theapplied anodic potential value. This was also confirmed by the electrochemical impedancespectroscopy data, which indicated that the nanocrystalline Al shows lower polarization and solutionresistances when compared to the microcrystalline Al. All results were in good agreement showingclearly that the nanocrystalline Al has less corrosion resistance and high corrosion rate in the ArabianGulf seawater due to the presence of many active centers on its surface.