镁合金微弧电泳复合膜层的微观结构和抗腐蚀性能

Microstructure and corrosion resistance of composite coating on magnesium alloy by microarc oxidation and electrophoresis

采用恒压模式在硅酸盐系电解液中制备镁合金微弧氧化陶瓷层,对比研究了微弧电泳和直接电泳镁合金的截面形貌、结合力大小以及抗腐性能差异.结果表明:在镁合金微弧氧化陶瓷层的表面可制备电泳有机层,简化了电泳工艺;在微弧电泳复合膜层间形成机械咬合力和化学键力,附着力等级可达1级;经800 h中性盐雾腐蚀试验后,复合膜层腐蚀增重量和样品表面的形貌均没有明显的变化;与微弧氧化陶瓷层和直接电泳有机层相比,微弧电泳复合膜层的电化学稳定性显著增强,腐蚀电流相分别减少了约5个和2个数量级.

Microarc oxidation （MAO） coatings on magnesium alloy were prepared in silicate electrolyte under constant voltage mode. Cross-section morphologies, binding force and corrosion resistance of the coatings treated by micro arc oxidation and electrophoresis or direct electrophoresis were studied, respectively. The results show that electrophoresis coating can be prepared on the surface of MAO coating, and this technique is simpler than the traditional electrophoresis. The forces of physical binding and chemical bonding of the composite coatings were formed, and the grade of binding force is NO.1. The corrosion weight and surface morphology of the composite coatings are not changed under the neutral salt spray test for 800 h. The electrochemical stability of the microarc oxidation and electrophoresis coating is better, and corrosion current is decreased by 5 or 2 grades compared by the ceramic coating or direct electrophoresis coating.