Fixed Area Preparation and Superhydrophobic Properties of Micro-nano Structures by Laser Electrodeposition Composite Process

Owing to unique wettability properties, superhydrophobic metal surfaces are extensively used for self-cleaning, anti-corrosion, anti-icing, microfluidics, and oil-water separation. A laser electrodeposition composite process (LECP) is used to prepare micro-nano structures. The structures are formed by a combination of copper micron cones and nickel nanocones. The work aims to create periodic copper micron cone structures on a sample surface through picosecond laser etching, followed by the removal of molten products via electrolysis. In addition, nickel nanocone structures were prepared by LECP in specific regions of the sample surface. The electrodeposition process was carried out with continuous laser irradiation of the sample surface by controlling the processing area and solution temperature through modulation of the laser parameters. Nickel ions were deposited as cones in a suitable temperature range due to the crystalline modifier in the solution. Samples were prepared under various conditions and analyzed comparatively for surface morphology, elemental content, internal structure, chemical composition, wettability, self-cleaning, delayed freezing, and corrosion resistance. To characterize the sample surface morphology and elemental content, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used. Additionally, an X-ray diffraction phase structure analyzer (XRD) was used to examine the internal structure. The contact angle (CA) and surface area (SA) of the sample were measured by an optical contact angle meter with a droplet volume of 5 μL. Each sample was measured at three different positions, and the results were averaged. The images were analyzed by ImageJ software. A high-speed video camera was utilized to record the droplet-bouncing process on the sample surface. Additionally, a digital microscope was used to record the self-cleaning process and the delayed droplet icing process on the superhydrophobic surface. Finally, the corrosion resistance of the superhydrophobic surface was tested with an electrochemical workstation for dynamic potentiodynamic polarisation (PDP). In this study, the fixed area preparation of selective micro-nano structures, consisting of Cu micron cone and Ni nanocone structures, has been achieved by LECP. The chemically modified micro-nano structures increase contact angle (CA) and decrease surface angle (SA). The combination of low surface energy and micro-nano structures results in a Cassie-Baxter state on the sample surface. The sample surface exhibits excellent superhydrophobicity, as evidenced by CA of 163° ± 2° and SA of 1° ± 0.5°. The icing time of water droplets on superhydrophobic surfaces prepared by LECP is extended by a factor of five, and the corrosion current density decreases by two orders of magnitude. By reducing the amount of heat exchange between the droplet and the environment, the air film forms when the superhydrophobic surface comes into contact with the liquid surface, extending the freezing time. At the same time, the air film hinders the contact between the corrosive solution and the metal surface, enhancing the corrosion resistance. In contrast to electrodeposition, LECP achieves a fixed area preparation of nanocone structures. The laser thermal effect heats the solution in a specific region to suitable temperature conditions, and the crystalline modifier induces the deposition of Ni ions as cones. © 2024 Chongqing Wujiu Periodicals Press. All rights reserved.