(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)
摘 要: 在硅酸盐体系中对AZ91D镁合金进行微弧氧化处理，探讨膜层致密性的研究方法，推导膜层密度的计算公式，定量分析膜层表面微孔的大小、分布及表面孔隙率随时间的变化，研究上述因素对膜层耐蚀性的影响。结果表明：成膜物质基本不随时间的变化而发生改变，使膜层的致密性可以通过密度来间接研究；随着时间的延长，膜层表面微孔逐渐变大，各微孔之间的大小差异及形状差异不断增大，膜层的表面孔隙率从8%逐渐增大到15%。处理时间为5和10 min时，膜层较致密，20 min后，膜层的致密度明显减小，时间继续延长，致密度基本保持不变。受膜层较大厚度、较高致密度、较少表面缺陷等多种优势共同存在的影响，30 min时，试样的耐蚀性最好。
关键字: 镁合金；微弧氧化；孔隙；致密性；耐蚀性
（State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals,
Lanzhou University of Technology, Lanzhou 730050, China）
Abstract:The coatings on AZ91D magnesium alloys were prepared by micro-arc oxidation (MAO) in silicate-containing electrolyte. The method to research the compactness of the coatings was discussed and a calculation formula of the density of the coatings was deduced. Meanwhile, the size and amount of the micro pores on the surface and the surface porosity of the coatings treated for different times were analyzed quantitatively. And the effect of the above factors on the corrosion resistance of the coatings was researched. The results show that, the phase composition of the coatings has no change with the extension of treatment time, so, the compactness of the coatings can be researched indirectly through the density of the coatings. With prolonging treatment time, the micro pores on the surface of the coatings become bigger constantly. The differences in size and shape of the micro pores also become more serious. The surface porosities of the coatings gradually increase from 8% to 15%. After treating for 5 and 10 min, the compactness of the coatings is large, however, after treating for 20 min, the compactness decreases greatly and basically remains unchanged. The corrosion resistance of the sample treated for 30 min is the best, because the coatings has a larger thickness, higher compactness and less surface defects on the surface.
Key words: magnesium alloy; micro-arc oxidation; micro-pore; compactness; corrosion resistance
