A comparative study of the corrosion protective properties of chromium and chromium free passivation methods
A comparative study of the corrosion protective properties of chromium and chromium free passivation methods
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DOI：
10.1016/j.surfcoat.2007.06.001
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发表时间：
2007-11-25
影响因子：
5.4
通讯作者：
Hornstrom, Sven-Erik
中科院分区：
文献类型：
--
作者：
Berger, Robert;Bexell, Ulf;Hornstrom, Sven-Erik
对热镀锌钢白锈保护的常用钝化方法进行了研究。钝化是基于三价铬或无铬。铬酸盐基转化涂层用于参考。测试经处理的板的白色防锈性和可涂性。用扫描俄歇电子能谱和X射线光电子能谱监测转化膜的表面化学。涂层厚度采用俄歇电子溅射深度剖面法测量，钝化层采用供应商推荐的厚度，因此显示出较大的变化。铬钝化层（无铬）的厚度约为75 nm。涂层中含有活性离子：（HO+）-O-3、Ti 4+、Mn 2+、Zn 2+、PO 4 3-。基于三价铬（Cr-III）的钝化层厚度约为30 nm，并含有活性离子：H3O + Cr3+、PO43-、F。铬酸盐基钝化层（Cr-VI）厚度约为5 nm，含有活性离子Cr 6 +/Cr 3+、F-。无铬钝化层和Cr-III钝化层在腐蚀测试中显示出相似的白色防锈保护。虽然没有完全达到铬-Ⅵ钝化的水平，但耐蚀性良好。来自涂漆板的测试结果表明，粉末涂料在所有三种钝化上都工作良好。溶剂型涂料在基于三价铬的钝化上效果最好。对于所有三种钝化，水性涂料在克利夫兰湿度测试中显示出差的抗起泡性。在该测试中，用六价铬钝化显示出比无铬酸盐钝化稍好的结果。(C)2007 Elsevier B.V.保留所有权利。
Commercially available passivation methods for white-rust protection of hot-dip galvanized steel have been investigated. The passivations were either based on trivalent chromium or chromium free. A chromate based conversion coating was used for reference. The treated panels were tested with regard to white rust protection and paintability. The surface chemistry of the conversion coatings was monitored with scanning Auger electron spectroscopy and X-ray photoelectron spectroscopy. Coating thicknesses were measured using Auger electron sputter depth profiling.The passivations were applied with a thickness recommended by the supplier and thus showed large variation. The thickness of the chromium passivation (Cr-free) is approximately 75 nm. The coating contains the active ions; (HO+)-O-3,Ti4+, Mn2+, Zn2+, PO43-. The passivation based on trivalent chromium (Cr-III) is approximately 30 nm thick and contains the active ions; H3O+ Cr3+, PO43-, F. The chromate based passivation (Cr-VI) is approximately 5 nm thick and contains the active ions Cr6+/Cr3+, F-.The Cr-free and the Cr-III passivations showed similar white rust protection in the corrosion tests. The corrosion resistance was good although it did not fully reach the level of the Cr-VI passivation. The results from the tests of the painted panels showed that the powder paint worked well on all three passivations. The solvent born paint worked best on the passivation based on trivalent chromium. The water born paint showed poor resistance to blistering in the Cleveland humidity test for all three passivations. In this test the passivation with hexavalent chromium showed slightly better results than the chromate free passivations. (C) 2007 Elsevier B.V. All rights reserved.