(1. 蘭州理工大學 省部共建有色金屬先進加工與再利用國家重點實驗室，蘭州 730050；
2. 蘭州理工大學 材料科學與工程學院，蘭州 730050)
摘 要: 在硅酸鹽電解液體系中，采用不同的陰陽極距離制備鎂合金微弧氧化膜層。通過TT260數(shù)字式渦流測厚儀、SEM、EDS和XRD分別檢測膜層厚度、微觀結(jié)構(gòu)、元素及相組成。采用Image-J軟件分析膜層表面孔隙率，利用電化學實驗研究膜層耐蝕性能。基于波形圖建立對應于微弧氧化系統(tǒng)的負載等效電路模型，并通過計算等效負載的數(shù)值和仿真，進一步分析其與膜層耐蝕性的關(guān)系。結(jié)果表明：隨陰陽極距離的增加，膜層表面微孔孔數(shù)增多，孔徑減小，孔隙率由26%逐漸降低到19%；膜層總體厚度隨距離的增加呈減少趨勢，但在距離為200 mm時略有增大；膜層耐蝕性呈先變好再變差的趨勢，即在距離為10 mm時，膜層的耐蝕性最差；距離為200 mm時，膜層的耐蝕性最好，兩者的腐蝕電流密度相差3個數(shù)量級。經(jīng)過計算和仿真驗證了負載模型的正確性，且計算的等效電阻R1與膜層耐蝕性具有對應關(guān)系，等效電阻R1值越大膜層耐蝕性越好，為現(xiàn)場評估膜層耐蝕性提供了依據(jù)。
關(guān)鍵字: 鎂合金；微弧氧化；陰陽極距離；微觀結(jié)構(gòu)；耐蝕性；負載模型
（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
