电场辅助AZ91D镁合金碳酸水溶液化学转化工艺

摘要

开发一种在 AZ91D 镁合金表面制备镁合金镁铝水滑石膜的电场辅助新工艺。该工艺可有效缩短镁铝水滑石转化膜的成膜时间。扫描电镜结果表明：短时间的电场辅助处理可在镁合金表面形成一层连续、致密的镁铝水滑石膜，但长时间处理会使膜层出现局部脱落现象。电场辅助处理2 h试样(EF1+1h)的腐蚀电流密度比镁合金基体低约2个数量级，交流阻抗测试和浸泡腐蚀试验结果均表明，该膜层能有效地保护镁合金。%A new method for synthesizing Mg−Al hydrotalcite conversion coating on AZ91D Mg alloy was developed by the application of electric field (EF). By using EF technique, the formation time of the coating can be significantly reduced. The SEM results indicate that a continuous and compact Mg−Al hydrotalcite coating is formed on the surface of Mg alloy after short time EF treatment. However, a long time treatment would make the coating partially exfoliate. The corrosion current density (Jcor ) of the coated sample (EF1+1 h) is approximately two orders of magnitude lower than that of Mg alloy substrate. The test of electrochemical impedance spectroscopy (EIS) and immersion corrosion also suggest that the coating can effectively protect Mg alloy against corrosion.