Electrochemical analysis of molybdate conversion coating on hot‐dip galvanized steel in various growth stages |
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| Authors: | Shuang‐hong Zhang Bo Yang Gang Kong Jin‐tang Lu |
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| Affiliation: | 1. Guangzhou Special Pressure Equipment Inspection and Research Institute, Guangzhou, China;2. School of Material Science and Engineering, South China University of Technology, Guangzhou, China |
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| Abstract: | The electrochemical behavior of molybdate conversion coatings in various growth stages was investigated by electrochemical impedance spectroscopy and equivalent circuits. The chemical composition and microstructure were characterized by SEM/energy dispersive spectroscopy, atomic force microscopy, and AES. Neutral salt spray tests complemented the information. The results indicated that the growth process of the molybdate conversion coating was accompanied by the growth of micro cracks, consisting of three stages: in the early and middle stages, the protective property of the coatings increased with increasing treatment time and then decreased when the cracks developed in the last stage. On the basis of the observation of the microstructure and the analysis of the electrochemical impedance spectra of the coatings in various stages, a simplified growth process model of the molybdate conversion coating on hot‐dip galvanized steel was created. Copyright © 2017 John Wiley & Sons, Ltd. |
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| Keywords: | hot‐dip galvanizing EIS molybdate coating corrosion |
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