负向电压对LA91镁锂合金微弧氧化膜耐蚀性的影响

Effect of Negative Voltage on Corrosion Resistance of Micro-arc Oxidation Ceramic Layer of LA91 Magnesium-Lithium Alloy

采用双极性脉冲电源控制变量法,分别得到不同负向电压和负向脉冲宽度下LA91镁锂合金的微弧氧化膜。通过扫描电镜和电化学方法比较不同工艺参数下合金微弧氧化膜的耐蚀性差异。结果表明:负向脉宽及负向电压大小均对微弧氧化膜耐蚀性影响较大,随着负向脉宽增大,膜层表面孔洞数量减少但孔径尺寸略有增大;当负向脉宽为65%时,微弧氧化陶瓷膜的质量较好,耐蚀性最佳;此外,过高或过低的负向电压均不利于微弧氧化膜的生长,负向电压为50 V时较为合适。

The micro-arc oxide film of LA91 magnesium-lithium alloy under different negative voltage and negative pulse width was obtained by the control variable method of bipolar pulse power supply.The corrosion resistance of alloy micro-arc oxide films under different process parameters was compared by scanning electron microscope and electrochemical methods.The results showed that the negative pulse width and the negative voltage have a great influence on the corrosion resistance of the microarc oxide film.As the negative pulse width increased,the number of pores on the surface of the film decreased but the pore size became larger.When the negative pulse width was 65%,the quality of the micro-arc oxidation ceramic film was better and the corrosion resistance was also the best.In addition,too high or too low negative voltage was not conducive to the growth of the micro-arc oxidation film.It is more suitable when the negative voltage was 50 V.