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| ELECTROCHEMICAL CORROSION BEHAVIORS OF ARC-SPRAYED ALUMINUM COATING |
| LIU Cun, ZHAO Weimin, AI Hua, WANG Yong, DONG Lixian |
| School of Mechanical and Electrical Engineering, China University of Petroleum, Dongying 257061 |
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Abstract Aluminum was deposited on steel using arc spraying, and the corrosion electrochemical behavior of the coatings in 3.5% NaCl aqueous solution was investigated. The electron probe micro-analysis (EPMA) was used to examine composition profiles of the coating cross section after 30 day immersion. The results showed that the corrosion medium could penetrate into the coatings along the pores or inclusions, and chloride ions have penetrated into the depth of the coatings. The potentiodynamic polarization curves showed the passivation phenomenon of the original aluminum coating, which was related to the strong adhesion of jelly corrosion product Al(OH)3 and the existence of Al2O3 films. The corrosion failure process of aluminum coating was investigated by means of electrochemical impedance spectroscopy (EIS) measurements. On the basis of the impedance diagram changes during the testing, the process can be separated into four stages: initiation of cavitations, acidification and hydrogen evolution in the hole, coating as the sacrificial anode when the corrosion medium penetrates into steel substrate and rapid development of cavitation groups. Finally various models for the electrode in the corrosion process were proposed.
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Received: 25 November 2009
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Corresponding Authors:
ZHAO Weimin
E-mail: zhaowm@hdpu.edu.cn
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