Achieving non-adsorptive anodized film on Al-2024 alloy: Surface and electrochemical corrosion investigation

By Khan, M. Faizan; Kumar, A. Madhan; Ul-Hamid, Anwar; Al-Hems, Luai M.
Published in Surfaces and Interfaces 2019

Abstract

Naturally formed oxide film on the surface of aluminum reduces corrosion rate to significant extent. Anodizing of aluminum is done to enhance this feature by increasing film thickness deliberately to desired level. In the current work, anodizing of Al-2024 alloy was carried out in sulfuric-acetic acid anodizing bath of different concentrations along with gradually increased applied potential. The structure and morphology of the developed anodized film was investigated with and without the addition of acetic acid. Structural and surface analysis results revealed the difference in the anodized layer formation with the presence of acetic acid in sulfuric acid bath. Electrochemical investigation was carried out to evaluate the surface protective performance of the formed anodized film in 3.5% NaCl solution. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) revealed that lowest corrosion rate with highest polarization resistance was achieved due to the presence of CH3COOH in the anodizing bath. Non-adsorptive and less porous anodized film noticed to be formed with the presence of CH3COOH in bath solution.

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