研究了添加剂镧盐和铈盐对304不锈钢表面着色膜的影响.实验条件为:铬酸酐250 g/L,硫酸270 mL/L,硝酸镧或硫酸铈0.4 g/L,温度85℃,反应时间8～13 min.分别制备了金黄色基础着色膜、镧着色膜和铈着色膜.采用FeCl3缝隙腐蚀试验、塔菲尔极化曲线、电化学阻抗谱(EIS)等方法对着色膜的耐蚀性进行了检测.结果表明,在铬酸-硫酸着色液中加入稀土能有效提高着色膜的耐蚀性,而镧盐的效果又优于铈盐.金相显微镜观察表明,镧盐和铈盐着色膜更加均匀致密.初步探讨了稀土提高着色膜耐蚀性的机制.%The effects of La and Ce salts as additives on colored films on 304 stainless steel surface were studied. Conventional colored film, La colored film, and Ce colored film, all in gold, were prepared from a coloring bath consisting of CrO3 250 g/L and H2SO4 270 Ml/L with and without La(NO3)3·6H2O orCe2(SO4)3·8H2O 0.4 g/L at 85 ℃ for 8-13 min. The corrosion resistance of the colored films were determined by FeCl3 crevice corrosion test, Tafel polarization curve measurement, and electrochemical impedance spectroscopy (EiS). The results indicate that the addition of rare earth to chromic-sulfuric acid coloring bath improves the corrosion resistance of colored films efficiently, and La has better effectiveness than Ce. The metallographic observation show that La and Ce salts make the colored film more uniform and compact. The mechanism that results in an improvement of corrosion resistance for the colored films obtained with rare earths is preliminarily analyzed.
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