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International Journal of Corrosion
Volume 2010, Article ID 528573, 6 pages
http://dx.doi.org/10.1155/2010/528573
Research Article

Electrochemical Impedance Study of Zinc Yellow Polypropylene-Coated Aluminum Alloy

1Lab of Metal Corrosion and Protection, Beijing Institute of Aeronautics Materials, Beijing 100095, China
2School of Material Science and Engineering, Beihang University, Beijing 100083, China

Received 10 May 2009; Revised 7 October 2009; Accepted 3 November 2009

Academic Editor: Flavio Deflorian

Copyright © 2010 Zhi-hua Sun 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

Performance of zinc yellow polypropylene-coated aluminum alloy 7B04 during accelerated degradation test is studied using electrochemical impedance spectroscopy (EIS). It has been found that the zinc yellow polypropylene paint has few flaw and acts as a pure capacitance before accelerated test. After 336-hour exposure to the test, the impedance spectroscopy shows two time constants, and water has reached to the aluminum alloy/paint interface and forms corrosive microcell. For the scratched samples, the reaction of metal corrosion and the hydrolysis of zinc yellow ion can occur simultaneously. The impedance spectroscopy indicates inductance after 1008-hour exposure to the test, but the inductance disappears after 1344-hour exposure and the passivation film has pitting corrosion.