锌表面混合稀土转化膜的阻抗研究

Study of Impedance of Rare Earth Conversion Coating on Galvanizing Coating

稀土转化能有效地改善镀锌层的耐蚀性能,某些条件下比低铬钝化效果更好,是代铬钝化的重要研究方向。为此,对镀锌件分别进行了低铬钝化和混合稀土转化处理。通过电化学测试,对比了镀锌层表面2种钝化膜的交流阻抗谱,比较分析了其腐蚀前后的交流阻抗谱及外观的变化,并考察了温度和处理时间对稀土转化膜阻抗的影响。结果表明,混合稀土能够在镀锌层表面形成耐蚀性优良的转化膜,此膜层受处理时间和温度的影响明显。

Low-Cr passivation coating and mixed rare earth conversion coating were prepared on the surface of galvanized wares. The electrochemical impedance spectra and appearance of the two types of passivation coatings before and after corrosion tests were investigated by conducting electrochemical measurements,and the effects of temperature and time on the impedance of the coatings were explored. Results indicate that the mixed rare earth is able to form conversion coatings with good corrosion resistance atop galvanizing coating,and the corrosion resistance of the rare earth conversion coatings is highly dependent on temperature and time.