Low-cost superhydrophobic coating on aluminum alloy with self-cleaning and repellency to water-based mixed liquids for anti-corrosive applications

This work seeks to develop a low-cost superhydrophobic coating on 5052 aluminum alloy using a combination of methods. First, top-down with acid etching with dilute HCl solution for a few minutes. Second, bottom-up by simple deposition of layered double hydroxide (LDH) film; Third, chemical modification of the surface with stearic acid. Through the applied methodology, it is possible to obtain superhydrophobic coatings with a contact angle of 164 degrees and sliding angles of 1 degrees. The obtained coating also shows high repellency and low sliding angle value for different commercial liquid foods such as orange juice, grape juice, chocolate milk, iced tea, isotonic, and cola-based soda. The Tafel method reveals that corrosion inhibition efficiency is 97.7 % and 97.4 % after 24 h of exposure in 0.6 mol/L NaCl solution and cola-based soda medium (pH = 2,5), respectively. The immersion test for 21 days (3 weeks) in distilled water and NaCl solution (0.6 mol/L) shows a change of the wettability characteristic on the coated specimens to hydrophobic and hydrophilic at the end of the experiment, respec-tively. Future work intends to incorporate harder particles that can further improve the mechanical durability of the LDH-based superhydrophobic coating, aiming at the application as food contact materials.