Effect of SO42- on the corrosion behavior of cerium-based conversion coatings on galvanized steel

被引:46
作者
Kobayashi, Yasuyuki [1 ]
Fujiwara, Yutaka [1 ]
机构
[1] Osaka Municipal Tech Res Inst, Dept Elect Mat, Joto Ku, Osaka 5368553, Japan
关键词
cerium; corrosion protection; conversion coating; sulfate ion; galvanized steel;
D O I
10.1016/j.electacta.2005.11.043
中图分类号
O646 [电化学、电解、磁化学];
学科分类号
081704 ;
摘要
The cerium-based conversion coatings on galvanized steel were investigated and the influence of SO42- on the corrosion behavior was evaluated. The coatings were prepared by a simple immersion of galvanized steels in an aqueous solution composed of cerium nitrate and sodium sulfate. The corrosion behavior was studied by means of potentiodynamic polanzation measurements and neutral salt spray tests. The addition Of SO42- to the coating solution considerably improved the corrosion resistance of the conversion coatings. Atomic force microscope observation shows that deposits prepared from the solution with SO42- have smaller crystalline size than those prepared without SO42-. The results of X-ray photoelectron spectroscopy and titration curves demonstrate that SO42- ions are incorporated in the coating during the conversion process. This indicates that SO42- acts as a grain refiner and/or growth inhibitor, thus enhancing the corrosion resistance. (c) 2005 Elsevier Ltd. All rights reserved.
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页码:4236 / 4242
页数:7
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