Corrosion Resistance and Corrosion Mechanism of the Superhydrophobic Coating Fabricated on Aluminum Alloy in the Salt Spray Corrosion Environment

A superhydrophobic coating is introduced to spread on aluminum alloy via spraying of epoxy resin adhesive, F-SiO2 nanoparticles, white fluorinated polyurethane coatings, and fluorosilicone varnishes. After a long time, the neutral salt spray accelerated corrosion (NSSAC) test, the surface morphology, and wettability of the superhydrophobic coating are individually characterized, and the corrosion mechanism, and variation law of corrosion resistance of the superhydrophobic coating are studied, respectively. When extending the time of the NSSAC test, the protruding micro-nano structure and cross-linked network structure of the coating are increasingly dismantled, the contact angle of the coating is decreased gradually, and the corrosion current density (CCD) of the coating increases progressively. The protruding micro-nano structure is less damaged before the 5th d of the NSSAC test, while it almost completely disappears after 30 d of the NSSAC test. The contact angle of the coating is 162.35 degrees before the NSSAC test, which remains greater than 150 degrees when the NSSAC test is carried out for 7 d, but decreases to 119.63 degrees after 70 d. The CCD of the coating increases to 4.62 x 10(-7) A cm(-2), which is two orders of magnitude lower than that of the non-corroded 2A12 aluminum alloy, after 70 d of the NSSAC test.