(1. 兰州理工大学 省部共建有色金属先进加工与再利用国家重点实验室，兰州 730050；
2. 兰州理工大学 材料科学与工程学院，兰州 730050)
摘 要: 在硅酸盐电解液体系中，采用不同的阴阳极距离制备镁合金微弧氧化膜层。通过TT260数字式涡流测厚仪、SEM、EDS和XRD分别检测膜层厚度、微观结构、元素及相组成。采用Image-J软件分析膜层表面孔隙率，利用电化学实验研究膜层耐蚀性能。基于波形图建立对应于微弧氧化系统的负载等效电路模型，并通过计算等效负载的数值和仿真，进一步分析其与膜层耐蚀性的关系。结果表明：随阴阳极距离的增加，膜层表面微孔孔数增多，孔径减小，孔隙率由26%逐渐降低到19%；膜层总体厚度随距离的增加呈减少趋势，但在距离为200 mm时略有增大；膜层耐蚀性呈先变好再变差的趋势，即在距离为10 mm时，膜层的耐蚀性最差；距离为200 mm时，膜层的耐蚀性最好，两者的腐蚀电流密度相差3个数量级。经过计算和仿真验证了负载模型的正确性，且计算的等效电阻R1与膜层耐蚀性具有对应关系，等效电阻R1值越大膜层耐蚀性越好，为现场评估膜层耐蚀性提供了依据。
关键字: 镁合金；微弧氧化；阴阳极距离；微观结构；耐蚀性；负载模型
（1. State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China;
2. School of Material Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China）
Abstract:The micro-arc oxidation coatings were prepared on AZ31B magnesium alloys in silicate-containing electrolyte at different anode-cathode distances. The thickness, microstructure, elements and phase composition of the coatings were measured by TT260 digital eddy current thickness gauge, SEM, EDS and XRD. The surface porosity of the coatings was analyzed by Image-J, and the corrosion resistance of the film was investigated by electrochemical experiments. Based on the waveform diagram, the equivalent circuit corresponding to the micro-arc oxidation system was established, and the equivalent load value was calculated to analyze the relationship between equivalent load value and corrosion resistance of the film. The results show that, with the increase of anode-cathode distances, the number of micro-pores increases while the size of micro-pores decreases, and the porosity gradually decreases from 26% to 19%. The film thickness decreases generally with the increase of the distance, but increases slightly at the distance of 200 mm. While the corrosion resistance of the film shows a tendency to become better first and then worse, that is, the corrosion resistance of the coating is the worst at the distance of 10 mm, and the corrosion resistance is the best the distance of at 200 mm. Their corrosion current density differs by three orders of magnitude. The calculated equivalent resistance R1 has a corresponding relationship with the corrosion resistance of the coatings. The greater the equivalent resistance R1, the better the corrosion resistance, which can be used to evaluate the corrosion resistance of the film layer on site.
Key words: magnesium alloy; micro-arc oxidation; anode-cathode distance; microstructure; corrosion resistance; load model
