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研究了一种新的AZ31B镁合金交流电微弧氧化(MAO)工艺,采用了对环境更加友好的含硅酸盐的稀碱溶液作为电解质。结果发现氧化过程分为2个阶段,膜厚与微弧氧化时间呈抛物线关系。形貌观察表明,微弧氧化膜由一个致密层和一个多孔层组成。致密层的厚度约占整个膜厚的40%,膜表面的20%均匀分布着直径1~3μm的孔。动电位极化测量显示,该新型微弧氧化膜的耐蚀性有明显提高,腐蚀电流降低了2个数量级,而自腐蚀电位正移了0.07V。盐雾试验结果同样证实微弧氧化膜的耐蚀性有大幅度提高。
A new AZ31B Magnesium Alloy AC Microarc Oxidation (MAO) process was studied, using a more environmentally friendly silicate-containing dilute alkali solution as electrolyte. The results show that the oxidation process is divided into two stages, the film thickness and the time of MAO shows a parabolic relationship. Morphology observation shows that the micro-arc oxidation film consists of a dense layer and a porous layer. The thickness of the dense layer accounts for about 40% of the total film thickness. The holes of 1 to 3 μm in diameter are uniformly distributed in 20% of the film surface. The potentiodynamic polarization measurements show that the corrosion resistance of the new MAO film is obviously improved, the corrosion current is reduced by two orders of magnitude, and the self-corrosion potential is shifted by 0.07V. Salt spray test results also confirmed that the corrosion resistance of micro-arc oxidation film has increased dramatically.