Facile fabrication of superhydrophobic aluminum surfaces by chemical etching and its anti-icing/self-cleaning performances

Abstract

In order to ensure the safety of civil aviation during the freezing weather, the application of superhydrophobic coatings (surfaces) on the aircraft is a useful and supplemental way to mitigate the accumulation of frost, ice or snow. In this work, superhydrophobic surface with hierarchical structure on SAE AMS 4037 aluminum alloy plate is prepared through chemical etching using hydrochloric acid and hydrogen peroxide with lower concentration successfully. Comparing with the bare aluminum substrate (untreated-Al), the superhydrophobic surface (treated-Al-11) possessed an excellent resistance to water, which water contact angle (CA) is as high as 163.6°, combined with minimum roll-off angle (RA) and contact angle hysteresis (CAH). The influences on wettability caused by different molar ratios of hydrochloric acid and hydrogen peroxide are studied by CA, RA, CAH and root mean square roughness (Rq). Hierarchical structure with irregular honeycomb-like protrusions and depressions of treated-Al-11 is found through SEM. Furthermore, treated-Al-11 is characterized by FTIR, EDS and XPS, which are demonstrated the presence of the aluminum stearate (AlSA) molecules on surface of treated-Al-11. Anti-icing tests are revealed that the weight of ice on the surface of treated-Al-11 with superhydrophobicity is significantly less than that of other Al plates at the same test time. The ice weight on treated-Al-11 is 1.7751 g compared to 1.9952 g on untreated-Al surface when test time is 120 min Based on the results of self-cleaning tests, the surface of treated-Al-11 is clean, however solution residues are remained on the untreated-Al surface.