Synergistic effect of pH and oxalate concentration on corrosion of aluminium alloy 2024-T3

ABSTRACT

This work aims at obtaining comprehensive information on the corrosion behaviour of AA2024-T3 in oxalic acid solutions under different concentrations (0.007–0.2 M) and pH (2–6). Various tests to characterise the corrosion behaviour are performed, including weight loss and electrochemical tests. Coupon surfaces are examined using infinite-focus microscopy, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, Raman spectroscopy and diffuse reflectance infrared Fourier transform spectroscopy. Corrosion rates, anodic and cathodic reaction kinetics are detailed to provide a fundamental understanding of the electrochemical behaviour of AA2024-T3 as a function of pH and oxalate concentration. The synergistic effect of pH and oxalate concentration on corrosion of AA2024-T3 is evaluated for both AA2024-T3 matrix and main intermetallics (i.e. Al–Cu–Mg and Al–Cu–Fe–Mn) and the electrochemical behaviour of each constituent element in AA2024-T3 is systematically studied.

KEYWORDS:

• Aluminium alloy 2024-T3
• oxalic acid
• pH
• DRIFT spectroscopy
• Raman spectroscopy

Acknowledgements

The authors would like to thank Dr Steven Cheung and Ms Sihan Wang from the Department of Polymer Science at the University of Akron for their help in running DRIFT/Raman characterisations and Dr Lingyan Li for helping with SEM-EDX scans. They also would like to thank Dr Lu-Kwang Ju for valuable suggestions. This work is in participation with the DoD Technical Corrosion Collaboration supported by the U.S. Department of Defense Office of Corrosion Policy and Oversight.

ORCID

Shengxi Li http://orcid.org/0000-0002-7788-4647

Hongbo Cong http://orcid.org/0000-0001-5263-6623

Bi-min Zhang Newby http://orcid.org/0000-0003-4052-2084

Additional information

Funding

The research is administered by the US Air Force Academy under agreement number FA7000-10-2-0013 (Projects FY11-TCC8 and FY12-TCC2 to the University of Akron).