Drag-reductive and anti-corrosive superhydrophobic surface fabricated on aluminum with thin PDMS/SiO2 coating

In this paper, thin PDMS/SiO2 composite film was prepared on the rough aluminum substrate after anodization. Wettability, microscopic morphology and chemical composition of consequent surfaces were obtained by contact angle measuring instrument, scanning electron microscope (SEM), energy dispersive spectroscopy(EDS) and fourier transform infrared spectroscopy(FTIR), respectively. Here, the water contact angle(CA) and sliding angle(SA) on the obtained surface reached similar to 160 degrees and similar to 1 degrees, separately. Afterwards, the solid/liquid friction of resulting surface was directly measured by drag reduction spraying system. Compared with untreated surface, it was found that the superhydrophobic surface (SHS) displayed favourable drag reduction ratio of 22%-36% at low velocity. Meanwhile, the electrochemical experiment illustrated corrosion current was smaller than that of the untreated sample. Significantly in harsh environments, for pH = 1 and pH = 13 droplets, the CAs were still larger than 154 degrees; even if oil contamination, self-cleaning performance was still achievable.