AZ91D镁合金Mo-Mn无铬转化膜的制备与耐蚀性

发布时间：2019-02-28 09:44

【摘要】：目的通过Mo-Mn无铬转化膜提高AZ91D镁合金的表面耐蚀性。方法采用正交实验法,研究不同浓度的NaMoO4和KMnO4以及温度对转化膜的影响。优选实验参数后,考察时间对转化膜的影响。利用SEM及EDS研究转化膜的微观形貌及成分变化,测试转化膜在3.5%NaCl溶液中的极化曲线和交流阻抗谱。结果当NaMoO4和KMnO4的质量浓度分别为10,6 g/L,pH=5,温度为50℃,转化时间为40 min时,转化膜颜色较为均匀,微观裂纹相对较少,自腐蚀电位比镁基体大约提高0.075 V,自腐蚀电流密度比镁基体降低近1个数量级。当Na Mo O4和KMnO4的质量浓度分别为20,8 g/L,pH=5,温度为50℃,转化时间为40 min时,转化膜颜色最为均匀,微观裂纹相对最少,自腐蚀电位比镁基体提高大约0.047 V,自腐蚀电流密度比镁基体降低2个数量级。交流阻抗谱图显示,后一种转化膜试样的极化电阻为1450.2Ω,而镁基体的极化电阻为806.4Ω。结论 Mo-Mn无铬转化膜可以显著提高AZ91D镁合金的表面耐蚀性。
[Abstract]:Objective To improve the surface corrosion resistance of AZ91D magnesium alloy by Mo-Mn chromium-free conversion film. Methods The effects of NaMoO4 and KMnO4 at different concentrations and temperature on the conversion film were studied by orthogonal experiment. After the experimental parameters, the effect of time on the conversion film was investigated. The polarization curves and the AC impedance spectra of the conversion film in 3.5% NaCl solution were studied by means of SEM and EDS. The results show that when the mass concentration of NaMoO4 and KMnO4 is 10,6 g/ L, the pH is 5, the temperature is 50 鈩，

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