A facile method for constructing scalable and low-cost superhydrophobic coating with anti-corrosion and drag-reduction properties

Through the reasonable design of the microstructure of superhydrophobic coatings, the solid-liquid contact area between the substrate and the liquid can be reduced, the penetration of corrosive medium into the liquid can be reduced, and the flow resistance can be lowered. In this paper, a bionic superhydrophobic composite coating of aluminum matrix material was prepared by the spraying method using KH550 coupling agent-modified silica (KH550@SiO2) and stearic acid-modified titanium dioxide (STA@TiO2) mixed with waterborne polyurethane. The performance was tested by water contact angle, drag reduction measurements, and electrochemical analysis. The composite coating has a droplet contact angle of 163.4° and a rolling angle of 4° and is extremely wettable. The synergistic effect of the air layer and coating densities resulted in excellent corrosion inhibition efficiency of the coating in a 3.5 wt % NaCl solution. In addition, the composite-coated spheres can form a continuous air cavity during water ingress, which is essential for extending the drag reduction capability of the coating in liquids. The design and preparation of superhydrophobic composite coatings have promising applications in large-area corrosion protection and voyage damping of metals.