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Inspired by the anisotropy of the rice leaf surface, high-speed wire electrical discharge machining (HS-WEDM) technology was used to build submillimetre-scale structures on the 304 stainless steel surfaces, and fluorination treatment was applied on the resulting surfaces. The wettability and microstructure of the resulting surfaces were investigated by a large depth 3D scanner, scanning electron microscopy and by the contact angle measuring instrument. The durability of the fabricated surface was evaluated by wear tests. Results show that the V-shaped groove arrays with a hierarchical structure on the processed surfaces are built by HS-WEDM. After the fluorination treatment, the as-machined surfaces show good one-direction superhydrophobicity and the obvious two-direction (the parallel and perpendicular groove directions) anisotropic wettability. The effect of the size of the V-shaped groove on the two-direction anisotropy is discussed. The wear tests show that the one-direction superhydrophobicity and the two-direction anisotropic sliding properties of the stainless steel surfaces are still exhibited after the tests. Fabricating rough surfaces by HS-WEDM is efficient and does not require complex process operation and large area three-dimensional features. This method can realise industrial production.

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In this work, bionic-superhydrophobic surfaces on aluminum alloy 5083 are fabricated by reciprocatingtype high-speed wire cut electrical discharge machining based on the hydrophobic property of the rice leaf. Submillimeter-scale rectangular grooves are processed on the surfaces. The superhydrophobic surface has shown a static contact angle of 158°, which is similar to the rice leaf. The morphological features are characterized by scanning electron microscopy, showing that the craters and bumps are uniformly distributed on the surfaces of the rectangular grooves with porous nanostructures. The method proposed in this work has the advantages of using only one step, requiring no further procedure to lower the surface energy and processing a large-area surface efficiently.

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