Corrosion Protection of a Novel Inhibitor@LDH Conversion Film on Steel: Insights from Long-Term Marine Atmospheric Field Experiments

The marine atmospheric environment, characterized by a high chloride content, high humidity, and a high corrosion rate of structural steel, urgently demands anticorrosion methods that are compatible with other technologies such as alloy steel and organic coatings. In this study, an inhibitor-loaded conversion film was grown in situ on a steel surface to prevent chloride-induced corrosion. Specifically, a Mg-Fe layered double hydroxide (LDH) conversion film was grown on the steel surface, and p-aminobenzoate (pAB−) inhibitor ions were intercalated into the LDH. After half a year of natural corrosion in the actual marine atmospheric environment, the average corrosion rate of steel with the inhibitor@LDH film was 36.20 µm/a, which was 21% lower than that of the steel substrate (45.91 µm/a). The inhibitor@LDH film also effectively suppressed local pitting corrosion, with the density of corrosion pits significantly reduced by 64%. Furthermore, the inhibitor@LDH film promoted the formation of a denser and thinner rust layer on the steel surface, with a smaller crack width, fewer cracks, and an increased α-FeOOH/γ-FeOOH ratio. In summary, the inhibitor@LDH conversion film inhibits general and local corrosion on steel in a marine atmospheric environment.