Effect of Hg2+ on the corrosion behavior of Al-2%Zn coatings on AA5083 in 3.5 Wt.% NaCl solution
Anti-Corrosion Methods and Materials
ISSN: 0003-5599
Article publication date: 17 March 2022
Issue publication date: 14 April 2022
Abstract
Purpose
This paper aims to study the effect of Hg2+ on the corrosion behavior of Al–2%Zn coatings on AA5083 in 3.5 Wt.% NaCl solution.
Design/methodology/approach
Potentiodynamic polarization and electrochemical impedance spectroscopy are used to investigate the effect of Hg2+ on the corrosion behavior. The surface and cross-sectional morphology are characterized by scanning electron microscopy and energy dispersive spectroscopy (EDS) to further reveal the corrosion mechanism of Hg2+.
Findings
The results show that the corrosion behavior of the coating changes significantly as the concentration of Hg2+ increases from 5 to 30 μg/L. The corrosion production film can inhibit the corrosion process when Hg2+ concentration is in the range of 0.5–5 μg/L, while Hg2+ can promote the corrosion process significantly when its concentration reaches to 30 μg/L. The generation rate of dense oxide film on the coating surface is faster than dissolution rate when the concentration of Hg2+ is in the range of 0–5 μg/L, which makes the coating “self-healing” and thus slightly slows down the corrosion rate. The EDS analysis shows that excessive Hg2+ are preferentially deposited at locations with inhomogeneous electrochemical properties, which in turn accelerates corrosion.
Originality/value
The corrosion resistance of Al-based coatings is significantly affected by Hg2+ in seawater. Thus, it is important to explain the corrosion mechanism of Al–2%Zn coatings under the combined effect of Hg2+ and Cl− in 3.5 Wt.% NaCl solution.
Keywords
Acknowledgements
This work was supported by National Natural Science Foundation of China (No. 51871164, No. U1960204), Research on ORV Corrosion Mechanism and Application of Prevention and Control Technology (2019-XSKJ-04), Tianjin Science and Technology Project (No.20YDTPJC01780) and Shandong Taishan Industry Leading Talents Project (No.SF1503302301).
Declaration of Competing Interest: The authors declare that there is no conflict of interests regarding the publication of this paper.
Citation
Xia, Y., Zhou, D., Gao, Z. and Hu, W. (2022), "Effect of Hg2+ on the corrosion behavior of Al-2%Zn coatings on AA5083 in 3.5 Wt.% NaCl solution", Anti-Corrosion Methods and Materials, Vol. 69 No. 3, pp. 261-268. https://doi.org/10.1108/ACMM-10-2021-2553
Publisher
:Emerald Publishing Limited
Copyright © 2020, Emerald Publishing Limited