Corrosion inhibition of aluminum alloy in chloride mediums by undoped and doped forms of polyaniline

Corrosion inhibition of Al 3003 alloy by pure undoped PANI (emeraldine base) and PANI doped with p-toluene-sulfonic, camphorsulfonic and dodecylbenzenesulfonic acids was investigated. Corrosion resistin g properties of PANI coatings with all artificially created hole defect were evaluated by electrochemical impedance spectroscopy (EIS) in aqueous 3.5% NaCl and 0.1 N HCl solutions. The highest corrosion inhibition factor was obtained for undoped PANI being equal to 12 and 4.4 in neutral and acidic media, respectively. The results indicated that corrosion protection of the bare aluminum alloy surface resulting front a defect of the PANI coating is in line with an increase of the thickness of the oxide layer protecting the aluminum alloy surface. The efficiency of corrosion protection of mild steel and aluminum alloy by polyaniline coatings was compared. (C) 2003 Published by Elsevier B.V.