Investigation of chemical etching and surface modification effect on the superhydrophobic, self-cleaning and corrosion behaviour of aluminium substrate

In this study, superhydrophobic surfaces were fabricated on aluminium substrates by chemical etching method and surface modification with perfluorooctyl trichlorosilane (PFTS). The superhydrophobic surface of the aluminium substrate was synthesized by two-step process: first, the roughness on the aluminium surface was created by the chemical etching method. Then, the surface energy of the rough aluminium substrate was reduced by immersion in the PFTS solution. The surface wettability was measured by a droplet contact angle measurement. The morphology and chemical composition of the surface were detected by field emission scanning electron microscope and attenuated total reflection-Fourier transform infrared methods, respectively. The self-cleaning properties of the coated and bare aluminium substrates were investigated. Corrosion behaviour of the samples was evaluated using Tafel polarization and salt spray methods. The contact angle measurement results showed that the surface roughness due to chemical etching reduced the contact angle on the aluminium substrate to 24° and after surface modification, the contact angle increased to 157°. In the Tafel polarization test, after creating a superhydrophobic surface, the corrosion current density and corrosion potential of the aluminium substrate reached from 94.3 to 28.82 (µA cm−2) and −0.695 to −0.68 V, respectively. The superhydrophobic aluminium surface showed self-cleaning effect.