Superhydrophobic Surface on Arc-Sprayed Aluminum Coating Via Fluorinated Polyurethane Modification: Preparation and Application in Corrosion Protection

This study aimed to prepare a superhydrophobic coating by applying low surface energy (LSE) materials to a rough surface, intending to achieve a corrosion-resistant coating. Polyurethane (PU) and fluorinated polyurethane (FPU) were synthesized via designed routes as LSE materials. Arc-sprayed aluminum (Al) coatings and 316L stainless steel substrates (316L SS) were used as the rough and smooth surfaces, respectively. The synthesized PU/FPU coatings were formed on the Al coatings and 316L SS, and their hydrophobicity and corrosion resistance were evaluated. The water contact angle test showed that the content of the fluorine and the concentration of the PU/FPU could affect the hydrophobicity of the surface. In addition, superhydrophobicity was achieved via applying FPU to a rough Al coating surface (Al-FPU coating). Furthermore, the Al-FPU coating also exhibited better corrosion resistance than that of the PU and the pure Al coatings according to Tafel polarization curves and electrochemical impedance spectra in artificial seawater. The results suggested that surface energy and surface roughness were correlated with hydrophobicity, and the modification via fluorinating can be an effective method to achieve superhydrophobicity and corrosion resistance for thermal-sprayed coatings.