Fabrication and anti-corrosion property of in situ self-assembled super-hydrophobic films on aluminum alloys

In situ rough structures on an aluminum alloy were formed by anodic oxidation method. After siloxane self-assembly on the rough structures, super-hydrophobic and self-cleaning films were fabricated. The static contact angle of the super-hydrophobic surface with a water drop was 157.5°±2.0° at its maximum and the contact angle hysteresis was less than 3°. The influence of anodic oxidation current density, the water content of the siloxane solution, and self-assembly time on film formation were studied by Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), atomic force microscopy (AFM) and contact angle measurements. Optimum parameters to fabricate the super-hydrophobic surface were obtained. FE- SEM and AFM results indicated that microstructures were obtained by anodic oxidation and nanostructures were obtained by the disorder of self-assembly film. Stable super-hydrophobic surfaces were produced by the cooperation of micro/nano-structures and the low surface free energy of the siloxane films. The electrochemical measurement (potentiodynamic polarization) indicated that the anti-corrosion property of the aluminum alloy was greatly improved by the in situ super-hydrophobic film.