Preparation and characterization of durable superhydrophobic protective coatings on aluminum alloy

The durable superhydrophobic protective coatings on the 7B04 aluminum alloy surface was prepared by using acid etching and boiling water bath to construct micro-nano hierarchical structure, and then spraying suspension containing aluminum phosphate adhesive (AP) and perfluorooctyltrichlorosilane (PFOTS) to increase adhesion and reduce surface energy. The samples were characterized by field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), contact angle measurement (CA), electrochemical impedance spectroscopy(EIS) and a variety of the environmental simulation experiments. The results showed that the static water contact angle (WCA) of the surface is 158.4° and the slide angle (SA) is about 0°, suggesting superhydrophobicity and low adhesion to water. The coating resistance (R_c) was as high as 101.55 kΩ· cm² and the charge transfer resistance (R_t) in NaCl corrosion medium increased by nearly two orders of magnitude, showing excellent protective performance. The sample can withstand a variety of damages, with ideal mechanical durability, chemical durability and environmental durability.