Production and Corrosion Resistance Mechanism of MgLiAlCe-LDHs@GO-5NH3 Composite Coating

This investigation utilized a micro-arc oxidation (MAO) coating, sealed with cerium salt, on the surface of a Mg-8Li alloy to provide endogenous metal cations for the development of Layered Double Hydroxides (LDHs). Graphene oxide (GO), known for its strong electronegativity, can adsorb these metal cations, facilitating the multi-directional nucleation and growth of LDHs. This process ultimately leads to the formation of a quaternary MgLiAlCe-LDHs@GO self-healing composite coating. The alteration in the MgLiAlCe-LDHs@GO coating when loaded with a corrosion inhibitor was examined. Via ion exchange, the inhibitor was incorporated into the LDH layers, with 5-aminosalicylic acid demonstrating the most effective results. The corrosion inhibitor and the cations within the LDHs form a uniform chelate barrier that fills the minute gaps between the LDHs, hence boosting corrosion resistance. Cerium hydroxide also precipitates at damaged sites. The combined action of these two self-healing mechanisms endows the composite coatings with good self-healing capabilities, establishing a dual self-healing mechanism for damaged areas. Notably, the corrosion current density of the MgLiAlCe-LDHs@GO-5NH3 coating was 5.61 × 10^-9 A·cm^-2.