Dissolution of cerium from cerium-based conversion coatings on Al 7075-T6 in 0.1 M NaCl solutions

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• 作者：Simon Joshi ; ^{sjwt5@mail.mst.edu} ; Elizabeth A. Kulp ; William G. Fahrenholtz ; Matthew J. O&rsquo ; Keefe
• 关键词：C. Pitting corrosion ; Aluminium ; C. Oxide coating ; A. Rare earth elements ; C. Anodic dissolution ; C. Passive films
• 刊名：Corrosion Science
• 出版年：2012
• 期刊代码：28_0010938x
• 类别：ch
• 出版时间：July, 2012
• 卷：60
• 期：Complete
• 页码：290-295
• 文件大小：688 K

摘要

Cerium-based conversion coatings (CeCCs) were immersed in 0.1 M NaCl for 鈭?00 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 pm>Km>_sp(CePO₄) 鈮?#xA0;pm>Km>_sp(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.