Corrosion inhibitor-loaded slippery liquid-infused porous surfaces with excellent corrosion resistance and dual self-healing for AZ31 Mg alloys

Nature-inspired Slippery Liquid-Infused Porous Surfaces (SLIPS) present a highly promising approach for protecting metallic materials against corrosion. In this study, we adopted a synergistic approach by integrating layered double hydroxides (LDHs), SLIPS and corrosion inhibitors to protect magnesium (Mg) alloys. The AZ31 Mg alloy was first subjected to LDH formation, followed by corrosion inhibitor loading and SLIPS fabrication. The nanoporous Mg–Al LDH structure served as a reservoir for lubricant and facilitated the loading of corrosion inhibitors. A systematic comparison of four organic corrosion inhibitors was carried out to evaluate their correlation with wettability, corrosion protection, and self-repairing behavior. The results revealed that the SLIPS loaded with 2–mercaptobenzothiazole (2–MBT) (denoted as M–SLIPS) exhibited the best performance, with an initial corrosion current density as low as 1.14 × 10⁻⁹ A·cm^–2, representing a four-order-of-magnitude reduction compared to the bare Mg substrate. After 14 days of immersion, the M-SLIPS coating maintained a low hydrogen evolution volume of 1.17 mL·cm^–2. Owing to the synergistic effect between the silicone oil and the corrosion inhibitor, the M–SLIPS coating effectively healed intentionally created surface scratches within 24 h, demonstrating dual self-healing capability. Overall, this study proposes a feasible and effective surface treatment approach, which could ensure the long-term corrosion resistance of Mg alloys.