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International Journal of Corrosion
Volume 2012, Article ID 915090, 7 pages
http://dx.doi.org/10.1155/2012/915090
Review Article

Corrosion Protection of Steels by Conducting Polymer Coating

Faculty of Engineering, Hokkaido University, Kita 13-jo, Nishi 8-chome, Kita-ku, Sapporo 060-8628, Japan

Received 1 March 2012; Accepted 30 March 2012

Academic Editor: Rokuro Nishimura

Copyright © 2012 Toshiaki Ohtsuka. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The corrosion protection of steels by conducting polymer coating is reviewed. The conducting polymer such as polyaniline, polypyrrole, and polythiophen works as a strong oxidant to the steel, inducing the potential shift to the noble direction. The strongly oxidative conducting polymer facilitates the steel to be passivated. A bilayered PPy film was designed for the effective corrosion protection. It consisted of the inner layer in which phosphomolybdate ion, P M o 1 2 O 3 4 0 (PMo), was doped and the outer layer in which dodecylsulfate ion (DoS) was doped. The inner layer stabilized the passive oxide and the outer possessed anionic perm-selectivity to inhibit the aggressive anions such as chloride from penetrating through the PPy film to the substrate steel. By the bilayered PPy film, the steel was kept passive for about 200 h in 3.5% sodium chloride solution without formation of corrosion products.