Development of cerium-based conversion coatings on 2024-T3 Al alloy after rare-earth desmutting

The deposition of Ce‐based conversion coatings onto 2024‐T3 Al alloy sheet was studied using Rutherford backscattering spectroscopy, scanning electron microscopy, Auger electron spectroscopy, x‐ray photoelectron spectroscopy and atomic force microscopy. The Al sheet was pretreated with an alkaline c...

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Bibliographic Details
Published in:Surface and interface analysis 2004-04, Vol.36 (4), p.290-303
Main Authors: Hughes, A. E., Gorman, J. D., Miller, P. R., Sexton, B. A., Paterson, P. J. K., Taylor, R. J.
Format: Article
Language:English
Subjects:
AES
AFM
conversion coating
RBS
SEM
XPS
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Summary:The deposition of Ce‐based conversion coatings onto 2024‐T3 Al alloy sheet was studied using Rutherford backscattering spectroscopy, scanning electron microscopy, Auger electron spectroscopy, x‐ray photoelectron spectroscopy and atomic force microscopy. The Al sheet was pretreated with an alkaline clean followed by treatment in a Ce(IV) and H2SO4‐based desmutter. The Ce(IV)‐based conversion coating solution contained 0.1 M CeCl3·7H2O and 3% H2O2 and was acidified to pH 1.9 with HCl. Upon immersion, there was an induction period that included activation followed by aluminium oxide growth over the matrix and cerium oxide deposition onto cathodic intermetallic particles and along rolling marks on the surface. After the induction period cerium oxide deposited generally across the whole surface and thickened. The strongest anodic sites initially were adjacent to the intermetallic cathodes and resulted in aluminium dissolution but also oxide thickening. Copyright © 2004 John Wiley & Sons, Ltd.
ISSN:0142-2421
1096-9918
DOI:10.1002/sia.1652