2198铝合金硫酸-己二酸阳极氧化膜耐蚀性

以2198铝-锂合金为研究对象,在硫酸-己二酸电解质溶液中进行阳极氧化,并对氧化后的试样进行沸水封闭处理。采用场发射扫描电子显微镜(FE-SEM)和原子力显微镜(AFM)对氧化膜的表面和截面的形貌进行观察。通过电化学阻抗谱(EIS)、塔菲尔(Tafel)曲线和浸泡实验来分析阳极氧化膜的耐蚀性能。结果表明铝-锂合金在阳极氧化过程中由于含铜合金相的影响,形成的氧化膜孔洞不完整出现连通现象;电化学测试结果表明封闭之后的氧化膜的耐蚀性明显提高,并且随着浸泡时间的延长拟合等效电路发生改变,同时多孔层和阻挡层的阻抗值在降低,说明在浸泡的过程中氧化膜的结构发生改变,耐蚀性降低。

Corrosion resistance of sulfuric-adipic acidic film for 2198 aluminum alloy

2198 Al-Li alloys were anodized in sulfuric-adipic acid bath, and then protected by boiling water sealing treatment. The surface morphology and cross-sectional morphology of the anodic film were evaluated by field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM).The corrosion properties of the anodic film were analyzed by electrochemical impedance spectroscopy (EIS), Tafel curve and immersion test. The anodic samples were respectively immersed in sodium chloride solution for different time, then EIS was used to analyze the corrosion behavior. The results show that some holes of the anodic film are connected because of the copper alloy phases. The result of EIS shows that the corrosion resistance of the anodic film after sealing treatment increases obviously, equivalent circuit changes with extension of immersion time, and the impedance of the porous and barrier layers decreases, so immersion process could change the structure of the anodic film and decrease the corrosion resistance.