关键词: 微弧氧化, 铝合金, 陶瓷膜, 微观结构, 耐蚀性

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