Oxide film formed on Al alloy beneath sulfosalicylic acid doped polyaniline incorporated into epoxy organic coating

The microstructure and chemical composition of the oxide film formed on the underlying Al alloy beneath sulfosalicylic acid doped polyaniline incorporated into epoxy organic coating (PANI-SSA/epoxy coating) after immersion in 3.5% NaCl solution was studied by SEM, TEM, XPS et al. Results show that the mixed oxide film is homogeneous, intact and dense with a nanocrystalline cluster structure. The thickness of the oxide film is about 300 nm. Further, the oxide film has proved to effectively protect the Al matrix and enhance the adhesion of the PANI-SSA/epoxy coating.