Anti-corrosion studies of novel conductive polymer coatings on aluminum alloys

We report the corrosion protection properties of a novel conductive polymer coating on aluminum alloys. The conductive polymer coating is a double strand molecular complex of polyaniline and a polyelectrolyte. The double strand polyaniline offers advantages in stability and processability over other forms of conductive polymers. The coated aluminum alloys (AA7075-T6) were evaluated for corrosion protection in an aggressive salt environment of .5N NaCl solutions using cyclic polarization and electrochemical impedance spectroscopy. Corrosion current densities were calculated for uncoated alloy samples and alloys coated with the conductive and non-conductive derivative of the double strand polymer. The conductive form of the double strand polyaniline coating shows a two order of magnitude lowering of the corrosion current over the uncoated samples and a one order magnitude lowering over the non-conductive form of the polymer coated samples. The shape of the cyclic polarization data closely resembles results of sulfuric acid anodized aluminum. This data indicates that the conductive state of the polymer is required for improved corrosion protection and an anodized type protection is occurring