Journal of South China University of Technology (Natural Science Edition) ›› 2007, Vol. 35 ›› Issue (3): 6-10.

• Mechanical Engineering • Previous Articles     Next Articles

Microstructure and Corrosion Resistance of Ceramic Coatings Formed on Aluminum Alloy by Micro-Arc Oxidation

Du Jun  Chen Dong-chu  Li Wen-fang  Zhang Yong-jun  Peng Ji-hua   

  1. School of Mechanical Engineering , South China Univ. of Tech. , Guangzhou 510640 , Guangdong , China
  • Received:2006-01-09 Online:2007-03-25 Published:2007-03-25
  • Contact: 杜军(1975-)，男，博士，讲师，主要从事复合材料与材料表面技术的研究. E-mail:tandujun@sina.com
  • About author:杜军(1975-)，男，博士，讲师，主要从事复合材料与材料表面技术的研究.
  • Supported by:

    广东省科技计划项目(2003C103013) ;中国博士后科学基金资助项目(2005038498)

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Abstract:

In this paper , a constant-current AC power supply with an asymmetric square-wave output mode was em-ployed to form Al2O3 ceramic coatings on aluminium alloy by micro-arc oxidation. The effects of processing parame-ters, such as the current density and the oxidizing time , on the microstructure and corrosion resistance of the pre-pared coatings were then investigated. The results show that the ceramic coatings are of excellent microstructure and property when the current density and the oxidizing time are respectively about 20 AI dmz and 15~20 min , and that a fairly short oxidizing time leads to uncoated areas on the specimen , while a fairly high current density results in many micro-cracks on the coatings , which all make the corrosion resistance of the coatings decrease. Moreover , it is found that the ceramic coatings are composed of both crystalline and amorphous Al2 O3 , and that there is no striking effect of the processing parameters on the phase composition in the asymmetric constant-current square-wave output mode.

Key words: micro-arc oxidation, aluminum alloy, ceramic coating, microstructure, corrosion resistance