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

• Published in: Surface & coatings technology 2023-03, Vol.457, p.129293, Article 129293
• Main Authors: da Silva, Rafael G.C., Malta, Maria I.C., de Carvalho, Lucas A.P., da Silva, Jedaías J., da Silva Filho, Walter L.C., Oliveira, Sara H., de Araújo, Edval G., Urtiga Filho, Severino L., Vieira, Magda R.S.
• Format: Article
• Language: English
• Subjects: AA5052; Anti-corrosion property; Liquid foods; Self-cleaning property; Superhydrophobic coating; Wettability
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2023.129293

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° and sliding angles of 1°. 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, respectively. 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. [Display omitted] •Superhydrophobic coatings were obtained from a low-cost and viable methodology.•Superhydrophobic coatings showed repellency for different commercial liquid foods.•The corrosive inhibition of the coating was 97.4 % in cola-based soda medium.•The coating presented hydrophobic behavior after 21 days immersion in distilled water.•The coating presented hydrophilic behavior after 21 days immersion in NaCl solution.