前处理对微弧氧化铝镁合金尺寸的影响

Effect of pretreatment on dimension of micro-arc oxidized aluminum–magnesium alloy

通过传统化学法和超声波清洗对高速动车电机C5M4铝镁合金端盖进行微弧氧化前处理，测量了端盖的尺寸变化，并研究了微弧氧化对端盖尺寸的影响。试验发现，微弧氧化后，端盖孔径变化在0．005～0．020mm之间，氧化膜厚度在0．005～0．014mm之间，说明微弧氧化对铝镁合金的尺寸影响不大。以传统的化学方法对端盖进行前处理，端盖孔径变化多在0．005～0．020mm内，部分在0．020～O．040mm之间，未能满足铝镁合金精密件对尺寸的要求。以超声波清洗技术对端盖进行前处理，端盖孔径变化则在0．005～0．010mm之间。超声波清洗对溶液温度和清洗时间的精确控制优于传统化学前处理，更适合于铝镁合金的微弧氧化前处理。

The end cover of EMU （electric multiple unit） traction motor, made of Al-Mg alloy C5M4, was pretreated by traditional chemical method and ultrasonic rinse prior to micro-arc oxidation. The effect of micro-arc oxidation on dimension of the end cover was studied by measuring its dimension variation. It was found that the pore diameter of the end cover changes in range of 0.005-0.020 mm and the thickness of oxidation film is in range of 0.005-0.014 mm, indicating that micro-arc oxidation slightly affects the dimension of Al-Mg alloy. The pore diameter varies basically within 0.005-0.020 mm and partly within 0.020-0.040 mm after pretreatment by traditional chemical method, which does not meet the requirement of dimension for Al-Mg alloy precision parts; however, it changes within 0.005-0.010 mm after pretreatment by ultrasonic rinsing. In the aspect of accurate control of solution temperature and rinsing time, ultrasonic rinsing is better than the traditional chemical pretreatment and more suitable to be used prior to micro-arc oxidation of Al-Mg alloys.