在硅铝复合电解液中, 采用不同的电参数在AZ91D镁合金表面制备微弧氧化膜。利用扫描电镜(SEM)观察了膜层表面微观形貌; 通过膜层测厚仪测量了氧化膜的厚度。结果表明, 随着电流密度、占空比或者氧化时间的增大, 膜层的不均匀程度都逐渐增大, 表面放电孔洞尺寸变大, 数量减少; 电流密度大于10 A/dm2或氧化时间超过15 min时, 微弧氧化过程会出现熄弧阶段; 膜层厚度随着电流密度的增加而呈现近似线性增加后趋于稳定的变化趋势; 而随着占空比或者氧化时间的延长, 膜层厚度则逐渐增大。

Ceramic coatings on AZ91D magnesium alloy were prepared by microarc oxidation with different electrical parameters in a silicate-aluminate dual electrolyte solution. Surface morphology and film thickness of the coating were characterized by scanning electron microscopy (SEM) and layer thickness meter. The results showed that the non-uniformity of the coating increased gradually with increasing the current density, duty cycle and oxidation time. The diameter of the discharge aperture increased but the number of discharge apertures decreased with increasing the current density, duty cycle and oxidation time. Extinguish arc stage appeared during the process of micro-arc oxidation when the current density was more than 10 A/dm2 or the oxidation time was more than 15 minutes. With the increase of current density, the thickness of the coating increased linearly first and then kept in a constant. Similarly, the thickness of the coating increased gradually with the increase of the duty cycle and oxidation time.