Fabrication of superhydrophobic aluminum with enhanced anticorrosive property

The current work mainly introduces a facile method to obtain superhydrophobic aluminum with a hierarchical micro-nanostructure by a combination strategy of anodizing, chemical etching, and surface modification using SiO2@PDMS coating via a simple chemical vapor deposition (CVD) method. Scanning electron microscopy (SEM), energy dispersive X-ray (EDS), EDS-mapping, X-ray diffraction (XRD) and water contact angle (WCA) measurements have been performed to characterize the surface morphology, chemical composition, phase structure, and wetting property of the surfaces, respectively. The SEM results showed that by anodizing a network of cylindrical nanoporous is formed. By etching, the diameter of these pores increases and surface modification using CVD causes the deposition of SiO2@PDMS nanoparticles over them. The WCA measurements showed that the samples of the anodized and anodized-etched aluminum after modifying with SiO2@PDMS nanoparticles become superhydrophobic with values of 153° and 154°, respectively. The corrosion resistance of samples was analyzed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The results displayed that the charge transfer resistance of the superhydrophobic surface of modified anodized-etched aluminum is 16700 kΩ cm2, which is 900 times higher than that of pure aluminum. Also, the positive shift of 0.385 V in corrosion potential and reduction of more than 3 orders of magnitude in corrosion current are observed compared with aluminum. All results show a significant improvement in the corrosion protection of Al due to anodizing and surface modification with superhydrophobic coating. This method is suggested as a simple technique to creating aluminum with superhydrophobic surfaces in industry.