镁合金新型氟钛酸盐电解液体系微弧氧化电参数的优化

Optimization of electrical parameters of micro-arc oxidation using novel fluotitanate electrolyte on Mg alloys

采用新型氟钛酸盐电解液对AM60镁合金进行微弧氧化处理,通过改变电流密度、氧化时间、频率和占空比4种电参数进行对比研究,采用SEM(扫描电子显微镜)观察材料的表面及截面形貌,采用EDX(能量色散X射线光谱仪)以及XRD(X射线衍射仪)确定其化学成分和相组成,通过极化曲线和阻抗谱对材料的耐蚀性进行评价。最终确定其最佳电参数如下:电流密度3 A/dm2、氧化至420 V、频率800 Hz、正占空比30%。所形成氧化膜表面的微孔在成膜过程被原位封闭,有效地解决了微弧氧化膜疏松多孔的问题。在最佳工艺条件下获得的微弧氧化膜自腐蚀电流密度可以达到1×10-7 A/cm2,其耐蚀性能优于传统电解液制备的微弧氧化膜的耐蚀性能。

A new fluotitanate electrolyte was used for preparing microarc oxidation （MAO） film on AM60 Mg alloys. Four electrical parameters, including current density, oxidation time, frequency and duty cycle, were investigated for determining the optimum parameters. The surface and cross-section morphologies were characterized by SEM （Scanning electron microscopy）. The chemical composition and phase structure were analyzed by EDX （Energy dispersive X-ray spectroscopy） and XRD （X-ray diffractometry）. The corrosion resistance was evaluated by polarization and EIS （Electrochemical impedance spectroscopy） measurements. The optimal electrical parameters are determined as follows：current density 3 A/dm2, oxidation at constant current to 420 V, frequency 800 Hz and positive duty cycle 30%. The micro-pores on the surface of the film are in-situ sealed during the film formation process, thus avoiding the porous structure as the traditional MAO film. The corrosion current density of the MAO film under the optimum processing conditions can reach 1×10^-7 A/cm^2, which is superior to the corrosion resistance of traditional MAO films.