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采用浸泡法在Q235钢镀锌层表面制备三价铬钝化膜,借助扫描电镜(SEM)和X射线光电子能谱(XPS)分析了钝化膜的表面结构与成膜过程.通过Tafel曲线、电化学阻抗谱和中性盐雾实验(NSS)结果评定钝化膜的耐蚀性.结果表明,镀锌层表面光滑均匀、结构致密,无明显裂纹;钝化膜表面平整,散乱且无规律分布着大量裂纹;钝化膜主要含有Cr、O、Zn和少量的P、N等元素,并以Cr(OH)3、Zn(OH)2、Cr2O3和ZnO等化合物的共混物形式存在.钝化膜的形成过程包括镀锌层的溶解、钝化膜的生长和溶解及钝化膜的干燥3个步骤.盐雾实验表明经过三价铬钝化后的镀锌件耐蚀性提高近7倍.“,”The trivalent chromium passivation film on the surface of Zn-plated Q235 steel was fabricated by immersion method.The microstructure and corrosion performance of the passivation film were studied by means of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS),as well as polarization curve measurement,electrochemical impedance spectroscopy (EIS) and neutral salt spray (NSS) test,respectively.The results show that the Zn-coating is compact without obvious cracks but with excellent anticorrosion performance.The trivalent chromium passivation film on Zn-coating has smooth surface with a large number of cracks.The major constituents of the trivalent chromium passivation film were Zn,Cr and O,while a small amount of P and N was also detected,which probably in the form of compounds such as Cr(OH)3,Zn(OH)2,Cr2O3,and ZnO.The forming process of passivation film possibly consists of three steps such as zinc dissolution,passivation film forming and dissolution,and finally drying to become passivation film.It is noted through NSS test that the trivalent chromium passivation film can enhance the corrosion resistance of Zn-coating by c.a.7 times.