及耐蚀性的影响
(1. 兰州理工大学 甘肃省有色金属新材料省部共建国家重点实验室, 兰州730050；
2. Faculty of Engineering, The University of Auckland, Auckland 1142, New Zealand)
摘 要: 研究硅酸盐体系中电压、频率和占空比等电参数对AZ91D镁合金微弧氧化膜层的厚度、表面形貌、相组成及耐蚀性的影响，并对膜层的表面孔隙率及表面孔径进行定量分析。结果表明：电压对膜层微观结构及耐蚀性能的影响起主导作用，频率的影响次之，占空比的影响较小；随电压升高，膜层厚度、表面孔隙率及耐蚀性均增大；频率与占空比对膜层厚度的影响不大，但对表面孔隙率和耐蚀性有一定的影响；频率为800 Hz、占空比为15%时，膜层耐蚀性较好，此时所得膜层的表面孔隙率较小，分别约为8%和10%，膜层表面上孔径在1~3 μm的微孔比例都大于60%；膜层表面孔径和孔隙率的定量评价与膜层形貌分析相结合可为膜层耐蚀性的分析提供有力依据。
关键字: 镁合金；微弧氧化；电参数；孔径；孔隙率；耐蚀性
microstructure and corrosion resistance of
micro-arc oxidation coatings on AZ91D magnesium alloys
（1. State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials,
Lanzhou University of Technology, Lanzhou 730050, China;
2. Faculty of Engineering, The University of Auckland, Auckland 1142, New Zealand）
Abstract:The effects of electrical parameters, such as voltage, frequency and duty ratio on the thickness, surface morphology, phase composition and corrosion resistance of the micro-arc oxidation (MAO) coatings treated with silicate aqueous solution on the AZ91D magnesium alloys were studied. The surface porosity and surface pore size of the MAO coatings were measured. The results show that the voltage demonstrates a main influence on the microstructure and corrosion resistance of coatings, and the following is the frequency while the duty ratio plays a weak role. The thickness, surface porosity and corrosion resistance of coatings increase accordingly with enhancing voltage, but the frequency and duty ratio have certain influence on the surface porosity and corrosion resistance of coatings while it is not the case for the coating thickness. The coatings present the best corrosion resistance when the frequency is 800Hz and duty ratio is 15%, their surface porosity are about 8% and 10%, respectively, and the percentage of pore size ranging in 1−3 μm reaches more than 60%. Combining the quantitative analysis of the surface porosity and pore size with the observation of surface morphology of coatings provide useful basis for the research of the corrosion resistance of coatings.
Key words: magnesium alloys; micro-arc oxidation; electrical parameters; pore size; porosity ; corrosion resistance
