电解液组成及工艺条件对镁合金微弧氧化过程的影响

在含有NaAlO2的电解液中以恒电流方式对镁合金进行微弧氧化。研究了电解液中NaAlO2、甘油、NaF的浓度以及电流密度和氧化时间对镁合金微弧氧化过程中电压-时间曲线和氧化膜厚度的影响。结果表明:电解液中只含有NaAlO2时即可产生火花放电现象,但得到的氧化膜较薄;甘油的加入可明显抑制尖端放电现象,NaF的加入可以显著增加氧化膜厚度,随着电流密度的增大,微弧氧化所需起火时间迅速缩短,而击穿电压并无明显变化,氧化膜厚度明显增加。采用扫描电子显微镜观察了镁合金微弧氧化陶瓷膜的微观形貌,在微弧氧化膜的表面存在明显的孔洞和放电通道,这些通道呈熔融状态结合在一起。

Effect of Constituents of Electrolyte and Operating Condition on Micro-arc Oxidation Process of Mg Alloys

Magnesium alloys were treated with micro-arc oxidation in a solution containing NaAlO2 at a constant applied current density.The effect of concentration of NaAlO2,glycerol,NaF in electrolyte and current density and oxidation time on voltage-time response of micro-arc oxidation process and coating thickness was also investigated.The results showed that sparks could be seen at the anode surface when the electrolyte only contained NaAlO2,the addition of glycerol can obviously restrain point discharge,the addition of NaF increased the coating thickness considerably.With the increase of the current density,ignition time of micro-arc oxidation become shorter.While the break voltage had no obvious change,and coating thickness increased obviously.The surface morphology of micro-arc oxidation coating was observed by scanning electron microscopy(SEM).The results showed that obvious pores and discharged tunnels which were melting and combined together can be seen on the coating surface.