Fabrication of superhydrophobic layered double hydroxide composites to enhance the corrosion-resistant performances of epoxy coatings on Mg alloy

In this work, a superhydrophobic MgAl-layered double hydroxide with F- intercalation (LDH-F) was fabricated by a facile method and further modification by stearate (St) anions. Then, the composite was dispersed in the epoxy resin to prepare anti-corrosion coatings, which was applied for corrosion protection of Mg alloy. This kind of coatings protects Mg alloy from some aspects. Firstly, the superhydrophobic film impedes the water molecules penetrating into Mg substrate. Secondly, the superior anions exchange ability of LDH can be used to stockpile chloride ions and the release of fluorine ions can react with magnesium ions to form a magnesium fluoride (MgF2) protective film at the corrosion area of the Mg alloy. Lastly, the LDH itself layered structure is a physical barrier. The fabricated composites were comprehensively characterized with Fourier Transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), water contact angle (CA) and scanning electron microscopy (SEM). Electrochemical Impedance Spectroscopy (EIS) was conducted to investigate the corrosion behavior of various composite coatings and the results demonstrated that the impedance modulus of the superhydrophobic layered double hydroxide epoxy (LDH-F-St-EP) coating reached 1.2 x 10(9) Omega cm(2), showing excellent anti-corrosion performances.

Automated summary

A superhydrophobic MgAl-layered double hydroxide with F- intercalation was fabricated and dispersed in epoxy resin to prepare anti-corrosion coatings for Mg alloy protection. The coatings act as barriers against water penetration, stockpile chloride ions, and form protective films at the corrosion area, showing excellent anti-corrosion performances.