电流密度对AZ31B镁合金微弧氧化膜组织与性能的影响

Effect of Current Density on the Microstructure and Properties of Micro-arc Oxidation Coatings for AZ31B Mg Alloy

在硅酸盐电解液系统下,采用直流脉冲电源对AZ31B镁合金微弧氧化膜的组织与性能进行了研究.XRD分析显示,氧化膜主要由MgO和Mg2SiO3构成.不同电流密度下氧化膜性能的对比研究结果显示,在获得40μm厚微弧氧化膜的过程中,随电流密度的增大,槽压升高、生长速度增大;但膜层的显微硬度与耐腐蚀性降低.进一步的SEM分析结果显示,电流密度的增大,导致陶瓷膜中的孔洞增大,致密性变差,从而降低了其硬度与耐腐蚀性.

The microstructure and properties of micro-arc oxidation （MAO） coatings for AZ31B Mg alloy in silicate electrolyte were investigated under the condition of DC pulsed power supply. XRD analysis showed that the oxidized coatings were composed of MgO and Mg2 SiO3. A comparative study of the prop-erties of the coatings under different current densities indicated that in the process of obtaining the 40 μm MAO coatings the cell voltage and growth rate rose with increasing current density while the micro-hard- ness and corrosion resistance decreased. Further SEM analysis demonstrated that the increase in current density led to the enlargement of the holes on the coatings and low compactness, reducing their hardness and corrosion resistance.