预制备膜特性对铝合金微弧氧化膜层形成过程的影响

Effect of characteristics of prefab coating on formation of microarc oxidation coating on aluminum alloy

利用交流脉冲微弧氧化电源在氯化钠和不同浓度硅酸钠电解液中对LY12铝合金进行表面处理,对比研究了样品表面有无预制备膜对微弧氧化起弧及生长过程的影响规律。结果表明:铝合金样品表面形成较高阻抗值的膜层是微弧氧化起弧现象得以发生的必要条件;样品表面获取预制备膜抑制了活性电极放电并为后期电击穿提供一个易"失稳"的界面状态,有利于缩短微弧氧化起弧时间,降低起弧电压,但预制备膜厚度和阻抗值大小对起弧时间和电压影响均较小;样品表面有无预制备膜微弧氧化电压-时间曲线有着相似的变化规律,且预制备膜在后期生长过程中重新参与成膜,在相同能量输出条件下所得陶瓷层厚度明显大于无预制备膜铝合金。

LY12 aluminium alloy was processed by microarc oxidation （MAO） in NaCl and Na_2SiO_3 solutions with different concentrations of Na_2SiO_3 using AC electrical source. The effect of prefab coatings on arc starting and growth during MAO process was researched. The results show that a coating with high impedance value formed on the sample surface is a necessary condition for arc starting. The discharge of active electrode is restrained by prefab coating, which offers an unstable interface state for microarc discharge to shortening arc starting time and reducing the voltage. No significant effect of thickness and impedance of prefab coatings on arc starting time and voltage is observed. Whether the prefab coating is prepared on the sample surface, the curves of voltage-time during MAO is similar. The prefab coating is concerned with forming ceramic coating, which results in a fast growth of ceramic coating under the same energy output.