几种稀土盐封闭的铝阳极氧化试样的腐蚀行为

Corrosion Behavior of Anodized Aluminum Sealed with Several Rare Earth Metal Salts Solutions

为提高铝硫酸阳极氧化膜的抗污染和防腐蚀性能,分别采用环境友好的铈盐、钇盐和镧盐溶液对阳极氧化膜进行了封闭处理。采用动电位极化法比较了不同稀土盐封闭的铝阳极氧化试样在弱酸性NaCl腐蚀介质中的电化学行为,采用扫描电子显微镜(SEM)和能量色散谱(EDS)对封闭试样腐蚀前后的表面形貌、组成进行了表征。结果表明:在腐蚀介质的侵蚀及强电化学极化条件下,铈盐和镧盐封闭的阳极氧化膜对铝基体具有较好的保护作用,而钇盐封闭膜的保护作用则较差。这种差别的主要原因是不同稀土盐封闭过程中封闭产物的析出倾向及速率不同。

Sulfuric acid anodized aluminum specimens were sealed respectively in environmental-friendly solutions of cerium, yttrium and lanthanum salts to improve the anti-contamination and anti-corrosive properties. Potentiodynamic polarization method was employed to study the electrochemical corrosion behavior of these rare earth metal salts sealed specimens upon immersion in acidic NaCl solution. The surface morphology and chemical composition of the specimens before and after corrosion tests were examined by scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）. It reveals that the coatings sealed with cerium and lanthanum salt solutions can provide strong protection to the aluminum substrates while that sealed with yttrium salt solution can only provide weak protection. The different corrosion behavior of the three kinds of rare earth metal salts sealed specimens was mainly tion tendency and rate of the different sealing processes. determined by precipitasealing products during