(Al 2 O 3 -SiO 2 ) sf /AZ91D镁基复合材料微弧氧化膜的制备及电化学阻抗谱分析 制备及电化学阻抗谱分析
摘要
A thick protective ceramic coating on 33% (Al2O3-SiO2)sf/AZ91D (volume fraction) magnesium matrix composite was prepared by the microarc oxidation (MAO) technique in silicate electrolyte. SEM, EDS and XRD were employed to analyze the surface morphology, composition and phase constituent of the coating, furthermore, the microhardness profile of the coating was also measured. The electrochemical corrosion properties of magnesium matrix composite before and after the MAO surface treatment were evaluated by electrochemical impedance spectroscopy (EIS), and the equivalent circuits corresponding to different immersion times were suggested. The results show that the fiber-reinforced composite surface is completely covered by the MAO coating. The ceramic coating mainly consists of MgO and Mg2SiO4 phases. The maximum microhardness of coating is up to