Robust and Chemically Stable Superhydrophobic Aluminum-Alloy Surface with Enhanced Corrosion-Resistance Properties

We report a simple method for fabricating micro-nanoscale structures consisting of irregular microscale plateaus with a self-assembled network of zinc oxide nanopetals on an aluminum alloy substrate. The method involves a combination of chemical etching with a hydrothermal process, followed by Polydimethylsiloxane coating via a simple vapor deposition method. Following the coating, surface displays superhydrophobicity with water contact angle of 161 degrees and a sliding angle of 4 degrees. The effect of morphological changes on wettability is examined by varying the hydrothermal processing time. The chemical stability of the superhydrophobic surfaces is examined in a wide range of corrosive media. After being immersed in a 3.5 wt% NaCl solution for 1 month, the surface retained its superhydrophobicity. The potentiodynamic polarization test results reveal that the superhydrophobic surface highly improves the corrosion resistance performance of the bare aluminum surface by three orders of magnitude. In addition, surface exhibited good mechanical durability against sandpaper abrasion, and long-term stability in the ambient environment. The proposed fabrication technique operating at relatively low temperature is simple and provides a new approach for production of large-scale three-dimensional superhydrophobic surfaces for various applications.