Superhydrophobic modification of aluminum alloy via chemical etching and phytic acid/metal ion self-assembly

Superhydrophobic aluminum alloy is fabricated through a chemical etching combined with surface modification. The surface modification step consists of a cyclic assembly of phytic acid (PA) and a metal ion (Ce or Fe) followed by surface modification with a low-surface-energy material (perfluorooctyltriethoxysilane, PFTS). With the optimized fabrication parameter, the sample integrated with Ce ion, denoted as Al-PA-Ce-PFTS, shows the best superhydrophobicity with CA of 169.6° ± 0.8° and SA of < 1°, followed by the sample integrated with Fe ion, denoted as Al-PA-Fe-PFTS (CA = 164.9° ± 2.1° and SA < 1°). Both samples determine excellent non-wettability. Through studying the dynamic behavior of water droplets on the surfaces of Al-PA-Ce-PFTS and Al-PA-Fe-PFTS, it reveals that both samples show excellent anti-adhesion ability. Electrochemical tests with 3.5 wt.% NaCl solution indicates that the anti-corrosion performance of superhydrophobic aluminum alloy surfaces is much better than that of the untreated aluminum surface. The freezing of water droplets on Al-PA-Ce-PFTS and Al-PA-Fe-PFTS is much slower than that of the untreated aluminum surface. Some water droplets can remain unfrozen at − 5 °C for over 60 min on the surfaces of Al-PA-Ce-PFTS and Al-PA-Fe-PFTS.