有机为主复合钝化的综合对比研究与展望

Comprehensive Comparative Study and Prospect of Organic-Based Composite Passivation

基于镀锌层表面无铬钝化技术,从钝化膜性质、钝化液稳定性和成膜耐蚀机理3大方面,总结了以硅烷、单宁酸和植酸为主要成膜物质的3种有机为主的复合钝化体系的优缺点。结果得出耐蚀性最优的体系为硅烷体系,且硅烷体系稳定性最好。单宁酸、植酸体系都能通过不同复配方法得到较丰富的颜色,但表面状态差。单宁酸和植酸体系耐蚀机理类似,钝化液环境导致单宁酸或植酸与Zn^(2+)反应生成配合物并形成螯环附着于基体表面,而硅烷可以分别与有机缓蚀剂、无机复配离子反应,形成Si-O-M共价键。列举了各体系的最佳配伍原则。通过综合对比得到硅烷体系作为主要成膜物质应用前景较好,其膜层耐蚀性优良、膜层结构最稳定、表面状态的缺陷最少,可与多种类型的缓蚀剂有协同缓蚀作用,得到的膜层具有良好的耐蚀性和自修复性。

Based on the chromium-free passivation technology for the galvanized layer, the advantages and disadvantages of four composite passivation systems with silane, tannic acid and phytic acid used as the main film-forming substances were summarized, from the aspects of the properties of the passivation film, the stability of the passivation solution and the corrosion resistance mechanism of the film. Results showed that the silane system had the best corrosion resistance and stability. Tannic acid and phytic acid systems could obtain rich colors through different compounding methods, but the surface conditions were poor. The corrosion resistance mechanisms of tannic acid and phytic acid were similar. The environment of the passivation solution caused tannic acid or phytic acid to react with Zn^(2+) to form a complex and form a chelate ring to attach to the surface of the substrate, while the silane could combine with organic corrosion inhibitors and inorganic complexes respectively to form the Si-O-M covalent bond. The best compatibility principles of each system were listed. This comparative study showed that the silane system had a better application prospect in being used as the main film-forming substance. Its film had excellent corrosion resistance, the most stable structure with the least defects. It could have a synergistic corrosion inhibition effect with various types of corrosion inhibitors, making the film have good corrosion resistance and self-repairability.