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Formation mechanism and properties of nonchromium
color passivation for zinc coating |
Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093, China |
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Abstract Galvanization can significantly improve corrosion resistance property of steel. However, the easy corrosion in humid environment can lead to losing protection to steel. In order to improve the corrosion resistance property, the chromiumfree silicate color passivation film was prepared on A3 steel with galvanized layer. Xray photoelectron diffraction spectra (XPS), scanning electron microscopy (SEM), electrochemical work station and neutral salt spray tests were used to investigate the composition, forming process and corrosion resistance. The results show that the obtained passivation film consists of Zn4Si2O7(OH)2·2H2O, SiO2, ZnO and Zn(OH)2. The neutral salt spray test can reach 75 hours, which is equal to commercial Cr3+ passivation.
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Received: 25 February 2014
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