A novel combined method for fabrication of stable corrosion resistance superhydrophobic surface on Al alloy

In this study, a highly stable superhydrophobic surface with excellent corrosion resistance was fabricated on the 6020 aluminum alloy. In this regard mixed shot peening-etching treatment and silane modification was used. The wettability of surfaces was studied by contact angle measurement. Also, the influence of the shot peening pretreatment on the corrosion resistance of fabricated samples was investigated in 3.5 wt% NaCl aqueous solution, using weight loss, and electrochemical impedance spectroscopy (EIS) tests. The contact angle of 153 degrees +/- 2 and the sliding angle of 8 degrees +/- 2 was obtained on a shot peened sample after silane modification. The corrosion test results show high corrosion resistance of modified shot peened sample which was attributed to the fabricated superhydrophobic surface. Functionalization of the surface with silane has been confirmed by Fourier Transform Infrared Spectroscopy FTIR by showing the Si-O-Si (987 cm(-1)) and Al-Cl (3100 cm(-1)) bonds. The effect of shot peening and silane modification on the morphology of the surfaces were determined by scanning electron microscopy SEM. Furthermore, the chemical stability of the samples during immersion in 3.5 wt. % NaCl solution for 3 days was examined by EIS and SEM tests. Also, the variation of the contact angle with immersion time was recorded. The variation of water contact angle on the superhydrophobic shot peened sample after 72 -hs of immersion time was shown to be negligible (water contact angle of 152 degrees after 3 days). In conclusion the extracted data from these tests confirmed the good chemical stability of the fabricated superhydrophobic surface on the shot peened sample.