Super-Hydrophobic and Oleophobic Aluminum Alloy Surfaces via Chemical Etching and Functionalization
Super-hydrophobic and oleophobic surfaces on ASTM 1200 H14 aluminum alloy substrates were achieved by chemical etching followed by the deposition of organically modified silicate coatings. The chemical etching solutions iron(III) chloride + hydrogen chlorine + hydrogen peroxide and etching time were varied to increase the surface roughness. The chemical etching produces rough surfaces with superficial square pores and edges about 1 μm–2 μm. The chemical modifications modified silicate solutions based on perfluorooctyltriethoxysilane (PFOTES) and hexadecyltrimethoxysilane (HDTMS) sol-gel precursors induced water contact angles about 154° and 150°, respectively. Moreover, the surface modification based on PFOTES demonstrated an oleophobic character with an oil contact angle of 136° due to air entrapment in the surface roughness at the oil-aluminum interface.