Fabrication of functional surfaces of aluminum alloy with a transition from superhydrophilic to superhydrophobic by nanosecond laser irradiation

The wettability of metal surfaces is of importance in different practical applications. In the present work, we investigated the role of alumina coatings in the variation of the surface wettability of aluminum alloys by nanosecond laser ablation. The superhydrophilic surface (water contact angle close to 0°) was successfully prepared, and the superhydrophilic surface was transformed into the superhydrophobic surface (water contact angle of about 151.4°) after non-fluorinated N-octyltriethoxysilane (OcTES) treatment. XPS results showed that the Al–OH (–OH) hydrophilic groups generated by coating decomposition occupied the main regions on the surface after laser ablation. After OcTES treatment, the OcTES molecules formed Si–O–Al bonds with the rough surface, which significantly increased the C–C(H) hydrophobic groups of the surface. The superhydrophobic surface showed good self-cleaning, anti-icing and anti-corrosion properties. The fabrication method is fast, non-toxic and environmentally friendly, which makes it potentially useful for engineering applications.