Easy functionalization process applied to develop super‐hydrophobic and oleophobic properties on ASTM 1200 aluminum surface

Super‐hydrophobic and oleophobic surfaces on ASTM 1200 H14 aluminum alloy substrates were achieved by chemical etching followed by deposition of organically modified silicate (ORMOSIL) coatings synthesized through sol‐gel method. The chemical etching using FHH solutions (FeCl 3 + HCl + H 2 O 2 ) was adapted for the studied aluminum alloy by varying the concentration of iron (III) chloride and the etching time in order to increase the surface roughness of the material. This chemical etching produces rough surfaces exhibiting superficial square pores with edges about 1 to 2 μm. The chemical modifications with ORMOSIL solutions based on 1H,1H,2H,2H‐perfluorooctyltriethoxysilane (PFOTES) and hexadecyltrimethoxysilane sol‐gel precursors induced water contact angles about 154° and 150°, respectively, and sliding angles smaller than 5°, on the previously optimized etched surface. Moreover, the surface modification with ORMOSIL based on PFOTES reached also an oleophobic character with an oil contact angle about 136° due to air entrapment in the surface roughness at the oil‐aluminum interface. Finally, ORMOSIL coatings produced with varied concentrations of PFOTES and tetraethoxyorthosilane precursors proved that the super‐hydrophobic and oleophobic properties can be maintained with an important decrease of the PFOTES precursor, which should significantly decrease the cost production of such functional surfaces and could favour its mechanical durability.