Dissolution of Cerium from Cerium-Based Conversion Coatings on Al 7075-T6 in 0.1M NaCl Solutions

Abstract

Cerium-based conversion coatings (CeCCs) were immersed in 0.1 M NaCl for ∼500 h over a range of pH (2.0–5.7) to investigate the dissolution of cerium species. Dissolution was detected by UV–vis spectroscopy only in the pH 2 solution. Similar cerium concentrations were detected from the dissolution of as-deposited and phosphate post-treated CeCCs. Solubility diagrams for Ce(OH)3, Ce(OH)4, CeO2, and CePO4 showed that only Ce(OH)3 was soluble in acidic conditions. Although pKsp(CePO4) ≈ pKsp(Ce(OH)3), the dissolution of the post-treated CeCCs was slightly higher than the as-deposited CeCCs. Thus, corrosion protection of CeCCs is not provided solely by dissolution of cerium species.

Department(s)

Materials Science and Engineering

Research Center/Lab(s)

Peaslee Steel Manufacturing Research Center

Keywords and Phrases

Pitting Corrosion; Aluminum; Oxide Coating; Rare Earth Materials; Anodic Dissolution; Passive Films

International Standard Serial Number (ISSN)

0010-938X

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2012 Elsevier, All rights reserved.

Publication Date

01 Jul 2012

Link to Full Text

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