A smart electroplating approach to fabricate mechanically robust and fluorine-free Ni-W alloys based superhydrophobic coating on Al alloy

In this study, a novel and smart electroplating method was presented to fabricate a mechanically robust superhydrophobic coating on Al alloys. The superhydrophobic coating was composed of Ni-W alloy film with high hardness and stearic acid (STA) with low surface energy, providing excellent abrasive resistance, anti-corrosion properties, and self-cleaning ability. Specifically, a thin transition layer of Al-Ni-W was pre-electroplated on the Al alloy substrate by utilizing Al as anode and Al alloys as cathode in Ni-W ions aqueous solution, which overcome the difficulty of directly electroplating alloys coating on the Al alloys surface. Finally, a robust composite superhydrophobic film was achieved after coating STA layer on Al alloy/Al-Ni-W/Ni-W substrate. As anticipated, the as-prepared Al alloys demonstrates excellent mechanical durability and chemical stability, including wear resistance, hardness, corrosion resistance and self-cleaning with a champion water contact angle of 163° and corrosion protection efficiency of 99.4%. The Leeb hardness of superhydrophobic film coated Al alloys was enhanced by 87.1% compared to the pristine Al alloys, increasing from 325 ± 3 to 608 ± 4. This method provides a universal pathway for fabricating robust superhydrophobic film on the active metallic substrates.