Synergistic Barrier–Inhibitor Protection of Aluminum Alloy via Vanadate-Loaded MgZnAl-LDH/Epoxy Coatings in Simulated Seawater

Document Type : Original Article

Authors

1 Department of Materials Engineering, Technical Engineering College-Baghdad, Middle Technical University, P.O. Box: 10001, Baghdad, Iraq

2 Scientific Research Commission, Ministry of Higher Education and Scientific Research, P.O. Box: 298, Baghdad, Iraq

Abstract

Layered double hydroxides (LDHs) are efficient nanocontainers for corrosion protection achieved through the release of inhibitors and capturing aggressive ions, but they have limited efficiencies of active species loading using conventional methods. This work proposes a novel dual-step intercalation approach that includes co-precipitation, followed by ion exchange to maximize the amount of vanadate incorporated into ternary MgZnAl-LDH. The LDH prepared was functionalized using 3-aminopropyltriethoxysilane (APTES) to improve the compatibility with the epoxy matrix. Morphological, chemical, structural, and thermal characterizations were carried out using FESEM, EDS, FTIR, XRD, and TGA for LDH. The functionalized LDH was incorporated into epoxy at different loadings (1, 2, 3, 4 and 5 wt. %) and applied as a protective coating on AA2024 aluminum alloy to enhance corrosion resistance in 3.5 wt. % NaCl solution. The MgZnAl-vanadate LDH/epoxy coatings were completely characterized for hardness, adhesion, contact angle, and surface morphology. Potentiodynamic polarization tests showed a significant enhancement in the corrosion resistance. The coating containing 2 wt. % LDH showed the best performance, with a protection efficiency of 99.97 %, Ecorr value of -0.521 V, and an extremely low icorr of 1 ×10⁻⁸ A·cm⁻². The unique improvement in performance is related to the synergistic effect of enhanced inhibitor loading, controlled release and improved dispersion in the epoxy matrix. 

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Main Subjects

References

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