A simple two-step approach for the fabrication of bio-inspired superhydrophobic and anisotropic wetting surfaces having corrosion resistance

As two typical aspects of the wettability based on bio-inspired functional surfaces, superhydrophobic and anisotropic wetting properties have attracted much interest in practical applications. However, how to use a simple approach to realize those properties is still a huge challenge; simultaneously, the corrosion resistance is also important when the surfaces are introduced into more complex environments. In this paper, a simple and highly effective two-step approach for the fabrication of bio-inspired superhydrophobic and anisotropic wetting surfaces is reported. Aluminum alloy (Al) plates were first structured using nanosecond laser, and then were placed in an oven for low-temperature annealing (100 degrees C). The results show that the nanosecond laser ablation not only builds dual- and three-level structures inspired by lotus leaf and rice leaf but also oxidizes the Al materials, resulting in an oxide film covering on the surface. After the low-temperature annealing, the as-fabricated surfaces display the superhydrophobic and anisotropic wetting properties by adjusting the scan spacing of adjacent microgrooves. The potentiodynamic polarization and electrochemical impedance spectroscopy tests show that the as-fabricated surfaces have excellent corrosion resistance that can provide an effective protection for the Al materials. In addition, this approach can be applied to a broad range of metals (stainless steel, copper and titanium). This research will be instructive for the applications of functional materials with the properties of superhydrophobicity and anisotropic wetting. (C) 2019 Elsevier B.V. All rights reserved.