Wire Electrochemical Machining of Nickel-Based Superhydrophobic Surface with Array Structures

Nickel-based materials are crucial in aerospace and marine engineering but suffer from corrosion in extreme environments. Wire electrochemical machining (WECM) can effectively create micro/nanocorrosion pits for planar superhydrophobic nickel surfaces, providing well corrosion resistance and antifouling capabilities for the substrate. Trans-scale array structures can further enhance the hydrophobicity of the substrate, but fabricating complex submillimeter arrays (such as inverted cones) on nickel remains challenging. Methods such as laser etching or electrical discharge machining cause thermal damage, tool wear, or poor accuracy. This study developed a strategy that combined precise three-dimensional WECM path planning to fabricate inverted cone- and gourd-shaped arrays, followed by optimized nitric acid-assisted secondary etching to construct hierarchical micro/nanorough structures. After modification with fluorosilane, the surface of the structure achieved a contact angle of 155°, demonstrating excellent superhydrophobicity. This method of "macroscopic array design + microscopic structure regulation" provided an effective solution for enhancing the protection of nickel-based surfaces under harsh conditions.