Corrosion inhibitors for corrosion resistance and self-healing of PEO/MgAlLa layered double hydroxides coating on Mg-Gd-Y-Zn alloy

A PEO/MgAlLa LDHs (P/MAL LDHs) coating was prepared by in-situ grown on the surface of Mg-Gd-Y-Zn alloy. The loading behaviors of metavanadate ion, tartrate ion, 3,5-dinitrosalicylate ion, 2-hydroxy-1,4-naphthoquinone anion and 4-aminophenol anion corrosion inhibitors were further investigated. The results showed that different inhibitors have different effects on the structures, morphologies, compositions, corrosion resistances, corrosion inhibition efficiencies and self-healing properties of the P/MAL LDHs coating. Among them, the P/MAL LDHs-A coating loaded with 4-aminophenol anion had the best corrosion resistance (corrosion current density i(corr) of 2.3 x 10(-10) A cm(-2), low-frequency impedance modulus value vertical bar Z vertical bar(0.01) of 8.3 x 10(7) Omega cm(2)). The P/MAL LDHs-A coating could complete self-healing within 24 h, whose corrosion resistance (vertical bar Z vertical bar(0.01) = 3.0 x 10(7) Omega cm(2)) was restored. Moreover, the corrosion resistance and self-healing mechanisms of the P/MAL LDHs-A coating were revealed.