约束阴极微弧氧化放电特性研究

利用Na₂SiO₃-KOH溶液体系,以工业纯铝为基体材料对约束阴极微弧氧化的放电特性进行了研究.考察了恒压模式下电极距离对氧化电流、电位分布及起弧电压的影响,并对电极距离与微弧氧化电能利用率间的关系进行了分析. 结果表明:对于阴阳极等约束条件下,随阴阳极距离加大,工作电流逐渐减小. 而对于仅约束阴极情况,工作电流随着阴阳极间距增加而增大. 这是由于增加阴阳极间距时,虽然约束阴极正下方试样表面的电场强度降低,工作电流减小,但远离约束电极处,阳极表面电场强度却增加,工作电流增大. 起弧电压随电极间距离的增大而升高,但阳极表面电场强度几乎保持不变. 微弧氧化陶瓷层厚度由处理中心沿半径向外逐渐变薄,且中心处陶瓷膜厚度随电极距离的增大迅速减小,电能利用率随之降低. 关键词： 微弧氧化 约束阴极 放电特性 电极间距

Discharge characteristics of confined cathode micro-arc oxidation

Confined cathode micro-arc oxidation (CCMAO) has been investigated in Na₂SiO₃-KOH solution with industrial pure aluminum as substrate materials. The effects of the electrode distance (ED) on working current, potential distribution, arcing voltage and so on have been focused on. The energy efficiency as a function of ED has also been evaluated. The results show the working current decreases with increasing ED for the same exposure area of confined cathode and anode. However, the working current increases with increasing ED with only the cathode confined. It is attributed to different electrical field on the anode surface. With increasing ED, the electrical field beneath the confined cathode decreases while that far from the cathode increases. This leads to a different total working current. The arcing voltage increases with increasing ED while the effective voltage on anode surface nearly keeps constant. The thickness of the ceramic coating produced at a small ED is much higher than that at a larger ED. The energy consumption per unit volume of oxides by CCMAO indicates that smaller ED leads to higher energy efficiency.