Fabrication of Au-AlAu₄-Al₂O₃ superhydrophobic surface and its corrosion resistance

Superhydrophobic Au-AlAu₄-Al₂O₃ surfaces have been successfully fabricated on aluminum substrate via immersion in chloroauric acid (HAuCl₄) aqueous solution and subsequent annealing treatment. The morphologies of the surfaces exhibit dendritic structures. The surface with remarkable superhydrophobic properties has a water contact angle of 171 ± 2° and a sliding angle of approximately 0°. The effects of the immersion time, immersion concentration, annealing time and annealing temperature on surface wettability were investigated in detail. The corrosion resistance of the untreated aluminum surface and the resulting Au-AlAu₄-Al₂O₃ surface were also investigated via the Tafel extrapolation method. The corrosion current densities are reduced by more than 1 order of magnitude for the resulting surface in comparison with the untreated aluminum surface. The anticorrosion properties of the surfaces get better over the immersion time and this may be due to the generation of corrosion products, which can prevent the corrosion process and protect the substrates. Moreover, the low current density of the resulting superhydrophobic surface demonstrates its excellent corrosion resistance.