Stannate and permanganate conversion coatings on AZ31 magnesium alloy

被引:139
作者
Zucchi, F. [1 ]
Frignani, A. [1 ]
Grassi, V. [1 ]
Trabanelli, G. [1 ]
Monticelli, C. [1 ]
机构
[1] Univ Ferrara, Dept Chem, Corros Study Ctr A Dacco, I-44100 Ferrara, Italy
关键词
magnesium alloy; EIS; polarization curve; conversion coating; corrosion resistance;
D O I
10.1016/j.corsci.2007.04.011
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
The formation of stannate and permanganate-phosphate conversion coatings on AZ31 magnesium alloy was investigated in situ by EIS measurements and their protective performances were studied by different electrochemical techniques in diluted (0.05 M) sodium sulphate solution. The influence that short or long treatment times exert on the performances of such conversion coatings is discussed. While permanganate-phosphate baths always built layers characterized by penetrating cracks, long stannate baths produced layers without interconnected porosity, but were defective. This accounted for the initial greater protectiveness achieved with the stannate treatment; nevertheless, the easy penetration of the electrolytic solution through such a layer quickly decreased its corrosion resistance. (c) 2007 Elsevier Ltd. All rights reserved.
引用
收藏
页码:4542 / 4552
页数:11
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