镀锌墨绿色钝化膜的制备与表征

Characterization and Preparation of Blackishgreen Colored Passivation Film on Galvanized Steel Sheet

在四酸溶液体系中,加入稳定剂(冰醋酸水溶液)及调色剂(银盐水溶液),对镀锌钢板进行墨绿色钝化处理;用扫描电子显微镜观察了钝化前后膜层的微观形貌,用能谱仪测定了成分,用X射线衍射仪分析了物相组成,用中性盐雾试验测试了耐蚀性。结果表明:未钝化试样表面为完整、粗糙的电镀锌层;钝化后表面变得均匀平整,呈现墨绿色,但有皲裂纹出现;钝化膜主要含铬、氧、磷、硫、锌及少量的铁元素,主要由CrPO4、Cr(OH)3、CrOOH、Cr2O3、Zn(OH)2、2ZnO.CrO3.H2O、Zn3(PO4)2.4H2O和Ag等相组成;镀锌层与钝化膜和铁基体之间的结合均较紧密,没有出现裂纹等缺陷;钝化膜耐中性盐雾腐蚀时间达400 h,满足国家与企业标准的要求。

Galvanized steel sheet was blackishgreen colored passivated in tetracid solution system with acetic acid solution as stabilizer and silver salt solution as toner. The micro-morphology of the film before and after passivation was observed by SEM. The composition of the film was tested by EDS and its phase compositon was analyzed by XRD. The corrosion resistance of the passivated film was studied by neutral salt spray test. The results show that the surface of the specimen without passivation film was complete consecutive and coarse electrodeposited zinc coating. The surface became homogeneous and smooth, and turned blackishgreen but had chap structure. The film was composed of Cr, O, P, S,Zn and a small amount of Fe element. There were phases in the film, including CrPO4, Cr（OH）s, CrOOH, Cr2Os,Zn（OH）2, 2ZnO·CrO3·H2O, Zn3 （PO4）2·4H2O and Ag. Zinc coating, passivation film and Fe matrix combined closely, and no defects appeared such as crack. The passivation film could endure neutral salt spray test for 400 h, which met the demands of national and enterprise standards.