Superhydrophobic surface with stepwise multilayered micro&nano-structure and investigation of its corrosion resistance.

We develop a fluorine-free preparation of the superhydrophobic surface on aluminum alloy with anti-corrosion performance and mechanical robustness. Surface morphology, chemical composition and water repellency were determined with SEM, CLSM, EDS, FT-IR, TG, and contact-angle measurement instrument, respectively. Aluminum matrix superhydrophobic surface (STA-PDMS-ZnO sample) was able to display excellent repellency to water with a WCA of 152° and a WSA of 2°. The outstanding superhydrophobicity on the as-prepared surface was greatly related to the construction of stepwise multilayered micro&nano-structure within the superhydrophobic surface. Due to the special surface structure, the mechanical robustness and corrosion resistance of STA-PDMS-ZnO sample were improved. Notably, the anti-corrosion mechanism by air pockets was explained by the comparison of two superhydrophobic surfaces even prepared with the same low-surface-energy chemicals. The superhydrophobic surface with multilayered micro&nano-structure (STA-PDMS-ZnO sample) showed greater corrosion resistance than the surface coated by superhydrophobic modification (Control sample). This is because of the entrapments of numerous air pockets within the aluminum matrix superhydrophobic surface, thus strengthening the corrosion resistance. On the basis of results, multidimensional superhydrophobic surface is promising to show good application future in the field of corrosion protection of metal.