镁合金微弧氧化-涂装体系的研究

提出了一种镁合金/微弧氧化膜/有机涂层的镁合金防护体系.在以硅酸钠为主的复合溶液中,利用双向对称脉冲电压在阴、阳极镁合金表面同时微弧电沉积陶瓷膜.利用盐雾实验比较了以镁合金微弧氧化膜为基底并涂覆环氧底漆和聚胺脂丙烯酸面漆的试样与镁合金/微弧氧化膜/有机硅、镁合金/微弧氧化膜/溶胶凝胶涂装试样的耐蚀性,并利用盐雾实验与交流阻抗谱相结合跟踪对比分析了镁合金/有机涂层、镁合金/铬酸盐转化膜/有机涂层、镁合金/微弧氧化膜/有机涂层的屏蔽性能.结果表明:采用溶胶凝胶、有机硅和有机涂层对微弧氧化膜进行涂装的方法均可进一步提高镁合金的耐蚀性,其中镁合金/微弧氧化膜/有机涂层试样可承受480h以上的中性盐雾实验,且其介质屏蔽性能优于镁合金/有机涂层和传统的镁合金/铬酸盐转化膜/有机涂层防护体系.

Painting of magnesium alloys based on microarc electrodeposition

A painting method based on a microarc oxidation (MAO) coating was applied to protect magnesium alloys. The MAO coating was simultaneously electrodeposited on the anode and cathode of AZ91D magnesium cast alloy with AC symmetric pulse method in composite silicate solution. Salt spraying tests were used to investigate the corrosion resistance of sol-gel, polysilicone, and organic epoxy primer and polyurethane acrylic topcoat coverings, which were considered as three post-coating methods to MAO specimens. After painted with epoxy primer and polyurethane acrylic topcoat, the barrier property of MAO samples was compared with that of Mg/paint and traditional Mg/chromate conversion coating (CCC)/paint specimens by salt spraying tests and electrochemical impedance spectroscopy (EIS). It was demonstrated that sol-gel, polysilicone and organic coatings all bear some validity, especially epoxy primer with polyurethane acrylic topcoat worked so well that no corrosion happened after 480 h of salt spraying. The shielding property of Mg/MAO/Paint was better than that of Mg/paint and Mg/CCC/paint.