Evaluation of the Corrosion Resistance of Different Galvanized Steels Treated in Cerium Salt-Based Solutions
| Autor: | Yon-Kyun Song, Leif Speckert, Florian Mansfeld |
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| Rok vydání: | 2006 |
| Předmět: | |
| Zdroj: | ECS Transactions. 1:133-152 |
| ISSN: | 1938-6737 1938-5862 |
| Popis: | Various treatments based on cerium salts have been evaluated in an attempt to develop surface modification treatments for galvanized steels that can replace the presently used processes that are based on hexavalent chromium. The substrates used in this study included pure zinc, electroplated zinc and zinc-nickel as well as hot dipped zinc and zinc-iron. In initial screening tests Zn and hot dipped Zn were immersed in Ce(NO3)3 or CeCl3 + H2O2 solutions at different concentrations and treatment times. The films formed in these solutions were sealed in Na2SiO3. The effect of the substrate chemistry was studied for bare electroplated zinc, zinc-nickel and hot dipped zinc as well as samples treated in a Ce(NO3)3 solution. Based on these results a new conversion coating process for electrogalvanized (EG) steel based on a cerium nitrate solution with several additives such as colloidal silica and silane has been developed that reduces the total treatment time to 70 seconds. The treated EG sample passed the 72 h salt spray test without white rusting. Similar improvements of corrosion resistance were obtained for the other types of galvanized steel. |
| Databáze: | OpenAIRE |
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