Effect of Post-Treatments on Corrosion and Electrochemical Properties of Anodized Al 2024-T3 Alloy

Document Type : Full-length article

Authors

1 Petroleum and Mining Engineering Dept. El Azhar university, Cairo, Egypt

2 Sianco - Egyptian Co. for Appliances and Maintenance, Cairo, Egypt.

Abstract

Anodizing is one of the most widely used surface treatments for aluminum and its alloys. In this process, a decorative and protective film of aluminum oxide is formed on the aluminum surface using a direct current electrical supply. In this research, anodizing in sulfuric acid followed by sealing in hot water, ammonium acetate and bichromate salt was performed to Al 2024-T3 alloy. Scanning electronic microscopy (SEM) / energy-dispersive X-ray spectroscopy unit (EDS), X-ray diffraction (XRD) and group of electrochemical technics were used to study the morphology and the electrochemical behavior of the specimens. The results showed that the sealing post-treatment decreased the cracks and sealed the pores on the anodic film surface to some extent depending on the sealing method. When Al 2024-T3 alloy sealed with bichromate, the surface became smoother and more crack-free than the other samples. Further, the corrosion properties showed a substantial improvement in the anti-corrosion properties of bichromate sealing compared to the anodized 2024 Al alloy with and without sealing in hot water and ammonium acetate solution.

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