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International Journal of Corrosion
Volume 2012 (2012), Article ID 368130, 8 pages
http://dx.doi.org/10.1155/2012/368130
Research Article

Evaluation of Corrosion Behavior of Galvanized Steel Treated with Conventional Conversion Coatings and a Chromate-Free Organic Inhibitor

1Faculty of Chemical Sciences, Universidad Autonoma de San Luis Potosi, Avenida Salvador Nava No. 6, 78290 San Luis Potosi, SLP, Mexico
2Institute of Metallurgy, Universidad Autonoma de San Luis Potosi, Avenida Sierra Leona No. 550, 78210 San Luis Potosi, SLP, Mexico
3Faculty of Engineering, Universidad Autonoma de San Luis Potosi, Avenida Salvador Nava No. 8, 78290 San Luis Potosi, SLP, Mexico

Received 1 June 2011; Accepted 29 August 2011

Academic Editor: Peter C. Okafor

Copyright © 2012 Laura A. Hernandez-Alvarado et al. 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

Conventional weight loss tests and both DC and AC electrochemical techniques were used to study if an organic inhibitor containing an alkanolamine salt of a polycarboxylic acid can substitute toxic coatings as chromating and certain phosphating procedures in the protection of galvanized steel. The electrolyte used was a 0.5 M aerated NaCl solution. All tests gave concordant results, indicating that the chromate-free organic inhibitor does protect galvanized steel in this environment, even though the provided protection was less than that of the chromate conversion coating. It was observed that, after a moderate initial attack, the corrosion rate diminishes due to the appearance and growth of passivating corrosion products layers, mainly constituted by zinc hydroxychloride ( Z n 5 ( O H ) 8 C I 2 H 2 O ) and two varieties of zinc hydroxide, among other crystalline compounds.