Micro-nano porous oxide layer was developed on AA2024 by phosphoric acid anodization process (PAAO). A low surface energy material (Fluoroalkylsilane-13) was applied on the developed oxide layer in order to reduce the wettability of the surface. The FAS modified surface exhibited hydrophobic with water contact angle of about 1300 and sliding angle of greater than 900. The structural changes of PAAO during natural ageing improved the hydrophobic property of the surface. The surface morphology analyzed by field emission scanning electron microscopy (FESEM) showed that the FAS coating was uniform and intact to the developed oxide layer. The AFM results revealed that there was about 30% decrease in Ra value after 30 days of natural ageing compared to freshly modified surface. This variation in the nanometer scale roughness due to the natural aging of PAAO caused the surface to superhydrophobic (SH) (WCA-1600 and sliding angle <50). Similar SH property had also been achieved by artificial ageing (vacuum heat treatment at 80°C for 1 h). Composition analysis by energy dispersive X-ray analysis (EDAX) revealed that the amounts of F and Si were higher in the case of vacuum heat treated specimen compared to the naturally aged. The potentiodynamic polarization experiments were conducted in 3.5% NaCl solution and the results were discussed
