Low-Adhesion Superhydrophobic SiO2-GF/Epoxy Coating on Al Alloy Resisting Concrete Adhesion and Corrosion

Despite aluminum alloys are widely employed in concrete environments, such as in nuclear spent fuel casings and concrete formwork, they remain susceptible to severe corrosion and adhesion caused by concrete, which considerably shortens their service life. The development of low-adhesion superhydrophobic coatings offers a highly promising strategy to enhance both corrosion resistance and anti-adhesion performance. Here, a low-adhesion superhydrophobic coating is fabricated on 6061 aluminum alloy via a facile and scalable spray-coating process. A robust epoxy-based composite reinforced with hydrophobic SiO 2 and glass fibers (GF) is employed, achieving a water contact angle of 156.2°. A glass fiber skeleton interwoven with SiO 2 nanoparticle constitutes a micro‑nano hierarchical structure, which together with low surface energy established a stable Cassie–Baxter state. This hierarchical structure traps an air cushion at the interface, significantly reducing the actual contact area between corrosive media and the substrate. As a result, the coating effectively resists adhesion from both dry cement powder and wet cement slurry, demonstrating notable self-cleaning and anti-adhesion performance. Electrochemical tests conducted in simulated concrete interstitial solution showed that the low-frequency impedance modulus of the superhydrophobic coating increased by more than four orders of magnitude, with a protection efficiency of 99.85%. Moreover, the low adhesion superhydrophobic coating also possesses outstanding mechanical durability, thermal stability, and chemical stability. Therefore, the low-adhesion coating shows great potential for the durable application of aluminum alloy in concrete environment.