Novel corrosion-resistant behavior and mechanism of a biomimetic surface with switchable wettability on Mg alloy

Abstract

Enlightened by anti-wetting living creature surfaces in nature, the superhydrophobic surface (SHS) and slippery liquid-infused porous surface (SLIPS) have been constructed on metal materials for solving engineering problems. In this research, we design a switchable surface between the SHS and SLIPS on Mg alloy to improve corrosion resistance and provide different water-repellent properties. The SHS and SLIPS are fabricated based on a laser-ablated polydimethylsiloxane@Al2O3@Fe2O3 coating (PAFC). After laser processing, the irradiated PAFC consists of micro/nanostructured texture resulting in excellent superhydrophobicity. The SLIPS is fabricated by filling the lubricant into the laser-structured texture of the SHS. Then, the surface can be easily switched between the SHS and SLIPS by alcohol washing and lubricant-infusion. The non-irradiated PAFC acts as a superior and durable corrosion barrier. Notably, the switchable surface exhibits an excellent anti-corrosion ability (with large impedance modulus at 10−2 Hz about 1011 Ω cm2) in both surface states, which does not have any degradation after being immersed in 3.5 wt% NaCl aqueous solution for 60 days. The SHS and SLIPS have durable air and lubricant layers, respectively, repelling the corrosive species during the immersion test. Simultaneously, the SHS and SLIPS can delay corrosion at an artificial defect area. The SLIPS performs better in the above abilities than the SHS owing to the lubricant layer's stability and self-healing property. The SHS with droplet rolling mode has better droplet transportability, water shielding ability, and self-cleaning ability than those of the SLIPS with droplet sliding mode in dealing with dynamic droplets. Meaningfully, the surface with switchable wettability exhibits long-term corrosion protection and promises a wide range of application prospects of metals such as anti-icing, drag reduction, anti-fouling, etc.