工艺参数对铝合金微弧氧化膜层蛇纹石含量的影响

为探究工艺参数对铝合金微弧氧化膜层中蛇纹石含量的影响,采用微弧氧化技术,分别在双向恒压、单向恒压和单向恒流模式下,在添加蛇纹石微纳米颗粒的电解液中进行试验,在ZL109铝合金表面原位生长陶瓷层。采用SEM、EDS及XRD对膜层进行分析。结果表明:在单向恒压和单向恒流模式下制得的微弧氧化膜层的蛇纹石含量相比双向恒压模式分别提高了92%和113%;微弧氧化膜层中的蛇纹石含量随电流的增加而增加,随频率的增加而降低,随电解液中蛇纹石微纳米颗粒浓度的增加而增加;试验过程中试样与电解槽之间的电场产生的电泳效应,使得在电解液中呈电负性的蛇纹石微纳米颗粒移动到试样表面,在接触到试样表面熔融态的高温氧化物时,蛇纹石微纳米颗粒表面熔化而粘合在试样表面,经电解液冷却复合到了微弧氧化膜层中。

Effects of Process Parameters on Content of Serpentine in Micro-arc Oxidation Coatings on Aluminum Alloy

In order to investigate the effects of process parameters on the content of serpentine in the micro-arc oxidation (MAO) coatings on aluminum alloy, the ceramic coatings on the ZL109 aluminium alloy surface were prepared by the MAO process in the electrolyte adding serpentine micro-nano particles under bidirectional constant voltage, unidirectional constant voltage and unidirectional constant current mode, respectively. The MAO coatings obtained were analyzed by SEM, EDS and XRD. The results show that the content of serpentine in the MAO coatings prepared by unidirectional constant voltage and unidirectional constant current mode increases by 92% and 113%, compared with the coatings that prepared by the bidirectional constant voltage mode. The content of serpentine in the MAO coatings increases with the increase of the current, decreases with the increase of the frequency, and increases with the increase of the concentration of the serpentine micro-nano particles in the electrolyte. The electronegative serpentine micro-nano particles in the electrolyte move to the surface of the sample due to the electrophoretic effect produced by the electric field between the sample and the electrolytic tank during the test, and its surface is melted and conglutinated to the surface of the sample when exposed to high temperature oxide on the surface of the sample, then it is cooled by the electrolyte and incorporate into the MAO coatings.