镀锌及锌合金层低毒、无毒钝化工艺

Research Progress of Low Toxic and Nontoxic Passivation Processes for Electroplated Zinc and Zinc Alloy Coatings

综述了国内外镀锌及锌合金层主要的低毒无毒钝化工艺。介绍了镀锌及锌合金层钝化原理和钝化体系。讨论了镀锌及锌合金层无六价铬钝化工艺的特点,包括三价铬盐钝化、钼酸盐钝化、稀土钝化、钛盐钝化、硅酸盐钝化、钨酸盐钝化和有机物钝化等,并针对各种钝化工艺的特点提出了有待完善的方面。通过分析讨论镀锌及锌合金层低毒、无毒钝化工艺,从成本和性能两个因素比较得出三价铬钝化技术是最有可能被接受的六价铬替代品,其次为钼酸盐钝化。指出了六价铬钝化工艺的替代势在必行,以及无毒或低毒、高耐蚀性和低成本的镀锌及锌合金层钝化工艺是今后的研究方向。

A review was given on the progress of the research on low toxic and nontoxic passivation processes for electroplated zinc and zinc alloy coatings.Thus the principle and liquid systems for the passivation of electrodeposited zinc and zinc alloy coatings were briefed.The features of low-valence chromium and chromium-free passivation processes were summarized,with the chromium(Ⅲ),molybdate,rare additives-,titanium salt-,silicate-,tungstate-,and organic compound-based passivation processes to be highlighted.Moreover,some suggestions were provided with respect to the improvement of various passivation processes used for the zinc and zinc alloy coatings.It was supposed that the passivation process operating on chromium(Ⅲ)salt could be the most promising substitute to chromium(Ⅵ) passivation process harmful to environment and human body.At the same time,the molybdate passivation process could be another substitute to the high-valence chromium process.With a view to the severe damage of the chromium(Ⅵ)passivation process to environment and human body,it was suggested to considerably strengthen the study on low toxicity or nontoxic chromium(Ⅵ)free passivation processes for the electrodeposited zinc and zinc alloy coatings.