探究无铬钝化膜的微观形貌和成膜机理。 方法 通过电化学实验评价钝化膜的耐腐蚀性能;通过扫描电镜观察钝化膜的微观形貌,探究其与耐腐蚀性之间的关系;通过 XRD,EDS,XPS 分析钝化膜的成分及组成。 结果 电化学实验表明,镀锌板经钝化处理后,钝化膜抑制锌层的阳极反应,有效降低腐蚀速率。 SEM 分析发现,钝化膜表面的平整度与其耐蚀性能无直接关系。 XRD 不能用于分析该工艺钝化膜的元素及组成。 EDS 和 XPS 分析结果表明,钝化膜主要含有 Zn,C,O,N,Si 等元素。 结论 有机大分子构成钝化膜的主要骨架,SiO2 和硅酸盐等吸附于立体骨架结构中,形成一层致密的钝化膜,起到抑制锌层阳极反应的作用。

Objective To study the microstructure and film-forming mechanism of chromium-free passivation film. Methods The corrosion resistance property of passivation film was determined by electrochemical tests. The relationship between the smoothness of the passivation film and the corrosion resistant properties was evaluated by SEM analysis. The element and constitution of passivation film were analyzed by XRD, EDS and XPS tests. Results After passivating treatment of the galvanized sheet, the passivation film could restrain the anodic reaction of zinc layer and decrease the corrosion rate. There was no direct relationship between the smoothness of the passivation film and the corrosion resistant properties as shown by SEM analysis. The element and composition of passivation film could not be tested by XRD but could be analyzed by EDS and XPS. The passivation film mainly contained zinc, carbon, oxygen, nitrogen, silicon etc. Conclusions The organic macromolecules formed the main frame in which SiO2 and silicate were absorbed. The unique combination formed a dense passivation film which could restrain the anodic reaction of zinc layer.