Active anti-corrosion of epoxy coating by nitrite ions intercalated MgAl LDH

Layered double hydroxide (LDH) with NO₂^- intercalation was successfully prepared via acidification oscillation and ion exchange. The nano-fillers were incorporated into the resin to prepare anti-corrosion coatings with the thickness of ca. 50 ± 5 μm. The electrochemical and self-repairing properties of the LDH-doped coatings were studied by EIS and LEIS. Results indicated that the addition of LDH loaded with nitrite induced obvious increased in the impedance of coating (from 4.64 × 10⁸ Ω cm² to 2.14 × 10¹⁰ Ω cm²) and improved the anticorrosion performance of the coating. In addition, the localized corrosion of coatings could be largely inhibited, and the released nitrite ions from LDH interlayers exhibited active anticorrosion functions. When LDH nanosheets were added to the coatings, the lamella structures improved the barrier performances of the coatings. At the same time, the excellent ion exchanges ability of LDH could be used as storage stations for chloride ions, and the release of nitrite ions could play an active anti-corrosion role. Both of them cooperated to synergistically improve the anti-corrosion performance of the coating.