Robust superhydrophobic coatings with multi-scale micro/nano structures for long-term corrosion protection of steel structures

Utilizing the extreme water-repellent properties of superhydrophobic coatings to prevent steel structures from being affected by water-based corrosive agents is considered an effective strategy. Nevertheless, they are often prone to insufficient durability and environmental resistance, hindering their long-term anti-corrosion performance. Herein, a facile and cost-effective method is proposed to construct a durable superhydrophobic coating for steel structures. Specifically, the coating utilizes pure epoxy resin as the adhesive base layer, constructs an intermediate layer with irregular micron-scale protrusions by spraying an epoxy resin mixture with stearic acid-modified SiO₂ microparticles, and applies stearic acid-modified TiO₂ nanoparticles onto the surface of the intermediate layer. The coating features a multi-scale micro/nano structure with hierarchical roughness and low surface energy, demonstrating promising superhydrophobicity with a WCA of 161.4° and a WSA of 3°. Consequently, the coating exhibits excellent self-cleaning and anti-fouling properties. The coating exhibits excellent mechanical durability, maintaining its superhydrophobicity after undergoing 200 tape peeling cycles, 200 g of sand impact, 28 m of sandpaper abrasion, or 80 Taber abrasion cycles. Meanwhile, the coating demonstrates exceptional chemical stability by preserving its superhydrophobic properties during prolonged immersion in various corrosive solutions. More importantly, the superhydrophobicity of the coating and the enhanced barrier effect resulting from the synergistic interaction of its components endow it with superior corrosion resistance. Under simulated acid rain corrosion conditions, the coating exhibits remarkable corrosion inhibition efficiency, with long-term retention of anti-corrosion performance. In summary, this study provides an effective strategy for long-term corrosion protection of steel structures, showing potential for practical applications.