锌镀层钼酸盐-氟盐金色钝化膜性能及形成过程的研究

Study on the Properties and Formation Process of Zinc-Plated Molybdate-Fluoride Gold Passivation Film

为给钼酸盐钝化工业化生产提供理论指导,采用钼酸盐作为主成膜剂对镀锌低碳钢进行钝化处理,探讨不同组分对钝化效果的影响以及最佳工艺钝化膜的形成过程。利用硫酸铜点滴试验和电化学分析,探讨钝化膜的耐腐蚀性能;通过SEM/EDS对比分析,得到不同工艺钝化膜的微观形貌及表面元素特征。结果表明:最佳钝化液工艺配方为20 g/L Na2MoO4、5 g/L NaNO3、5 g/L KF;F-作为活性剂活化锌,促进显色反应的进行,最终使钝化膜外观呈金色;最后推出了最佳工艺下钝化膜的形成过程:钝化液中的F-活化了镀层中的锌使其形成Zn2+,随后Zn2+、Fe3+、MoO<sup>2-4、OH-、H+相互反应形成了H2MoO4·H2O、Zn MoO4、Fe(OH)3、Zn(OH)2,最后得到金黄色钝化膜。

In order to provide theoretical guidance for the industrial production of molybdate passivator,the molybdate was used as the main film-forming agent to passivate the galvanized low-carbon steel.The influence of different components on the passivation effect and the best process for the passivation film formation were discussed.Subsequently,the copper sulfate drop test and electrochemical analysis were used to explore the corrosion resistance.By using the SEM/EDS comparative analysis,the morphology and surface element characteristics of passivation films prepared with different processes were obtained.Results showed that the optimal process formula was as follows:20 g/LNa2MoO4,5 g/L NaN O3and 5 g/L KF.As an active agent to activate zinc,the fluoride ion promoted the color reaction to endow the passivation film with golden color,and the formation of passivation film under optimal process was deduced in the end.Namely,the F-in the passivation solution activated the Zn in the films into Zn2+,and then the interaction of Zn2+,Fe3+,MoO42-,OH-and H+formed H2MoO4·H2O,ZnM oO4,Fe(OH)3 and Zn(OH)2,which obtained the golden yellow passivation film finally.