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International Journal of Corrosion
Volume 2012, Article ID 760284, 9 pages
http://dx.doi.org/10.1155/2012/760284
Research Article

Deposition of Cerium-Based Conversion Coatings on Aluminum Alloy 380

Materials Research Center and Department of Materials Science and Engineering, Missouri University of Science & Technology, Rolla, MO 65409, USA

Received 11 May 2012; Revised 18 July 2012; Accepted 23 July 2012

Academic Editor: Ingrid Milošev

Copyright © 2012 Ci Lin 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

Cerium-based conversion coatings were deposited on as-cast aluminum alloy 380 substrates by a spontaneous immersion process. In this study, the effects of rinsing temperature prior to immersion in the coating deposition solution were studied with respect to the surface morphology, electrochemical response, and corrosion resistance of the coatings. Panels rinsed at 25C prior to coating had large cracks and holes in the coating. In contrast, panels rinsed at 100C prior to coating had a uniform coating morphology with fewer, smaller cracks. Electrochemical testing revealed that coatings deposited on substrates rinsed at 100C had higher impedance (~80 kΩ·cm2) and lower corrosion current (~0.34 𝜇A/cm2) compared to coatings deposited on substrates rinsed at 25C, which had 10 kΩ·cm2 impedance and 2.7 𝜇A/cm2 corrosion current. Finally, ASTM B117 salt spray testing showed that rinsing at 100C prior to coating resulted in cerium-based conversion coatings that could resist the formation of salt tails for at least 8 days.