Controlling Superhydrophobicity of Aluminum with Hierarchical Micro-Nanostructure Film for Superb Self-Cleaning and Anti-Corrosion

In this study, typical electrodeposition method was proposed to fabricate uniform CuO hierarchical micro-nanostructure on aluminum (Al) substrate. The superhydrophobic protective film was then fabricated by modifying stearic acid (STA) on this hierarchical CuO film. The static water contact angle reached up to 163 degrees by coating CuO/STA film on Al substrate, and the rolling-off angle was as low as 3.7 degrees. In addition, CuO/STA coated Al displayed wonderful non-sticking performance when the free-falling water droplets contact the surface. As expected, superb anti-corrosion properties of Al were achieved by coating superhydrophobic CuO/STA film on Al. The corrosion current density of CuO/STA coated Al decreased 2 orders of magnitude comparing with that of pristine Al, and the corrosion protection efficiency of CuO/STA coated Al reached up to 98 % in comparison with pristine Al. Therefore, superhydrophobic CuO/STA film coated Al substrate greatly prolong the working life of Al materials in harsh working condition. The universal method used in this study also provides a potential route for coating superhydrophobic and anti-corrosion protective film on other metallic substrates or conductive substrates.