Effect of the polymer layers and bilayers on the corrosion behaviour of mild steel: Comparison with polymers containing Zn microparticles

• Published in: Progress in organic coatings 2005-12, Vol.54 (4), p.285-291
• Main Authors: Herrasti, P., Recio, F.J., Ocón, P., Fatás, E.
• Format: Article
• Language: English
• Subjects: Applied sciences; Bilayers; Coatings. Paints, varnishes and inks; Corrosion; Corrosion mechanisms; Exact sciences and technology; Metals. Metallurgy; Polyaniline; Polymer industry, paints, wood; Polypyrrole; Uses; Zn microparticles
• ISSN: 0300-9440; 1873-331X
• DOI: 10.1016/j.porgcoat.2005.07.001

Electrodeposition methods have been used to obtain polypyrrole and polyaniline polymer layers, bilayers and blends of these polymers on carbon steel by passivation of the steel surface in the electrodeposition solution (oxalic acid and monomer) between −0.5 and 0.3 V versus Ag/AgCl and subsequent electrodeposition using different techniques (potentiodynamic, galvanostatic and potentiostatic). The results obtained indicate that prepassivation gives rise to adherent polymer layers with excellent corrosion resistance. Of all the bilayers obtained, the best results are yielded with those in which polyaniline is deposited as the base for the deposition of polypyrrole. The electrodeposition of Zn microparticles on the previously deposited polymer layers promotes a great improvement in the corrosion current in highly aggressive solutions such as NaCl due to the effect of Zn as an anodic corrosion inhibitor. The drop in the corrosion rate depends on the amount of Zn deposited on the polymer layer, up to a certain point after which the protective effect ceases to be observed.