## 3 Results and Discussions
### Corrosion Resistance  
Superhydrophobic surfaces were elaborated by the three proposed methods. This reduction in the wettability of these surfaces may deeply affect their corrosion resistance. For this reason, the corrosion resistance of the prepared samples was evaluated. Table 4 shows the open circuit potential values (OCPs), in seawater, of the different prepared samples. The results clearly demonstrate that the OCP is strongly influenced by the presence of silane on the aluminum alloy surface [46]. Indeed, all the silanized surfaces showed OCPs more noble than the non-silanized ones. In addition, the corrosion resistance can be roughly estimated by means of a potentiodynamic polarization test. Figure 7 shows the potentiodynamic curves recorded for the as-received sample (A_R) and the three superhydrophobic samples with different water contact angles/water sliding angles in 3.5 wt.% NaCl solution. The electrochemical parameters such as the corrosion current density (Icorr) and the corrosion potential (Ecorr) derived from the potentiodynamic polarization using the Tafel extrapolation approach are also reported in this figure. A lower corrosion current density (Icorr) and a higher corrosion potential (Ecorr) indicate a better corrosion resistance [24; 47]. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Code** & **OCP(V)** & **Ecorr (V vs. SCE)** & **Icorr (\(\mu\)A/cm\({}^{2}\))** \\ \hline A\_R & \(-\)0.931 & \(-\)0.906 & 21.17 \\ A\_RS & \(-\)0.786 & & \\ A\_W & \(-\)0.769 & & \\ A\_WS & \(-\)0.698 & \(-\)0.735 & 0.04 \\ A\_N & \(-\)0.645 & & \\ A\_NS & \(-\)0.537 & \(-\)0.449 & 0.03 \\ A\_F & \(-\)0.620 & & \\ A\_FS & \(-\)0.472 & \(-\)0.419 & 0.03 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Open circuit potential values (OCP) of AA6082 surfaces after different treatments steps in 3.5 wt.% NaCl solution. It can be seen that the corrosion potential of the aluminum alloy positively increases in the presence of superhydrophobic surfaces from \(-\)0.906 to \(-\)0.734 V for the A_WS sample, \(-\)0.449 for the A_NS sample, and then \(-\)0.419 mV for the A_FS sample. The low corrosion resistance of the untreated  
Figure 7: Polarization curves of A_R, A_WS, A_NS, and A_FS. aluminum alloy is due to the pitting corrosion that occurs after immersing in an aggressive environment containing Cl\({}^{-}\). However, the corrosion current density decreases by about three orders of magnitude (from 21.17 uA x cm\({}^{-2}\) for the untreated surface to \(\leq\)0.04 uA x cm\({}^{-2}\) for the superhydrophobic surface), demonstrating that the instantaneous corrosion rate of aluminum alloy decreases when the water repellency of the surfaces increases. The order of corrosion resistance is A_FS, A_NS, A_WS, and A_R. This order is consistent with water repellency results, where sliding angles to the superhydrophobic surfaces were in the order of A_WS > A_NS > A_FS. In particular, the A_FS is the noblest specimen thanks to its high water repellency. Thus, the elaborated superhydrophobic aluminum alloy surfaces have better corrosion resistance than the as-received AA6082-T6 alloys. In fact, the corrosion behavior of the samples is affected by the surface morphology. The superhydrophobic surface traps air within the valleys on the hierarchical interface when immersed in seawater (3.5 wt.% NaCl) solution. Therefore, the trapped air in micro/nano-hierarchical structures of the superhydrophobic samples acts as an \"air cushion\" to prevent the penetration of corrosive ions (Cl\({}^{-}\)), effectively resulting in excellent corrosion protection [48; 49; 50]. These results are in significant accordance with literature. In fact, [PERSON] et al. [27] showed that the superhydrophobic aluminum alloy surfaces have better corrosion resistance than untreated aluminum alloys. In addition, [PERSON] et al. [51] found that the superhydrophobic surfaces improved the corrosion resistance of aluminum in sterile seawater.