Robust superhydrophobic composite coating with dual-sized particles for self-cleaning and anti-corrosion of 5083 aluminum alloy

Biomimetic superhydrophobic materials inspired by the unique non-wetting properties of natural organisms provide an important solution for enhancing the corrosion resistance of aluminum alloys. In this study, a selfcleaning and anti-corrosion superhydrophobic coating with self-similar structures was constructed on 5083 aluminum alloy substrates using dual-sized particles (micro-scale PTFE particles and nano-scale F-TiO2 particles) combined with epoxy resin. In-depth investigations on the prepared coating were conducted, including surface wettability, morphologies, and chemical compositions. The fabricated superhydrophobic coating features superior mechanical robustness and maintains its superhydrophobicity after 160 sandpaper abrasion cycles (32 m abrasion distance) and 40 tape-peeling cycles, which can be attributed to its micro-nano hierarchical self-similar structures. Additionally, the substrate protected by the PTFE@F-TiO2@EP superhydrophobic coating exhibited a typical Cassie-Baxter contact state, excellent self-cleaning of solid contaminants, and resistance to liquid adhesion. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests confirmed a significant improvement in corrosion resistance, with the surface charge transfer resistance (Rct) increased by six orders of magnitude and the corrosion current density (Icorr) reduced by five orders of magnitude. We believe this multi-functional protective coating, combining superhydrophobicity, self-cleaning, corrosion resistance, and mechanical stability, holds promise for expanding potential applications across various scenarios.