Ultrafast and Eco-Friendly Fabrication Process for Robust, Repairable Superhydrophobic Metallic Surfaces with Tunable Water Adhesion.

Superhydrophobic metallic surfaces with a water contact angle greater than 150° have attracted considerable attention in both fundamental research and industrial applications due to their special properties such as antibiofouling, drag reduction, self-cleaning, anti-icing, anticorrosion, and oil-water separation. Until now, the development of superhydrophobic practical applications is mainly limited by the process complexity, long fabrication time, coating with toxic materials, and easily damaged surface structure. To reduce the fabrication time, and simplify the process for industrial applications, an eco-friendly postprocess has been developed in this research. The superhydrophobic surfaces on the laser-textured titanium, aluminum, copper, stainless steel, and nickel substrates were fabricated extremely rapidly by a simple surface modification of only a 10 min heat treatment with nontoxic silicone oil. Hydrophobic organic group absorption has been accelerated on the silicone oil heat-treated surface and has created a low-energy surface. In addition, we demonstrated the potential of using the laser areal fluence parameter, which could be an alternative to single-laser process parameters such as scanning speed, power, and step size, to fine-tune the water adhesion behavior. Therefore, a surface that integrates different water adhesion behaviors can be easily fabricated for more complex practical applications such as controlled microdroplet transportation, microfluidic systems, and certain biomedical processes. Moreover, the robustness of superhydrophobic surfaces was confirmed by abrasion tests, knife-scratch tests, chemical durability tests, and aging tests, and their repairability was evaluated for product applications in practice.