Influence of desiccation procedures on the surface wettability and corrosion resistance of porous aluminium anodic oxide films

A hydrophobic oxide film was formed on aluminium by anodizing followed by desiccation treatment. Films subjected to gradual heating and cooling exhibit larger water contact angles than samples exposed to fast heating and cooling at the same temperature. From SEM and Auger Electron Spectroscopic observations, the low wettability surface shows a regular porous morphology with no significant chemical composition differences due to the different treatments. The desiccation process improves the corrosion resistance, shown by immersion in NaCl. The change in morphology by the desiccation processes is considered a main reason to lower the wettability, which further affects the corrosion properties.

► Simple desiccation treatment without coating or etching produces hydrophobicity of porous anodic oxide film.
► Treatment time can be shortened by controlling desiccation condition.
► Surface microstructure is the key point to determine the wettability.
► The hydrophobic surfaces show better corrosion resistance than oxide aluminium.