不同金属杂质对碱性锌酸盐镀锌层结构及耐蚀性的影响

Influence of Different Metal Impurities on Structure and Corrosion Resis‐tance of Zinc Coating Formed in Alkaline Zincate System

碱性锌酸盐镀锌体系镀液成分简单、镀层结构致密,废水易于处理,因而有望取代氰化物镀锌。然而,由于镀液中不含强配位剂,因此镀液对杂质的敏感性较高。为了有效保证镀层质量,本文采用三维视频显微镜、电化学测试等方法系统的研究了Fe^(2+)、Pb^(2+)、Cu^(2+)等常见金属杂质离子对镀层形貌、耐蚀性及晶粒取向的影响。结果表明,铁杂质在0.05 mol/L的浓度范围内,对于镀锌层外观无明显的影响,但会降低其耐蚀性,而且会抑制锌在(110)晶面方向上的生长速度。铜离子浓度大于0.01 mol/L时降低了镀层外观质量和耐蚀性,而且降低了锌层的(110)晶面的强度,提高了其(100)与(101)的晶面强度。铅离子含量达0.001 mol/L以上会极大影响镀层外观以及耐蚀性,同时它也降低了锌层(110)晶面的强度。

Alkaline zincate plating system has the simple bath composition,the dense coating structure and the easy treatment of wastewater,so it is expected to replace cyanide zinc plating.However,the bath does not contain strong complexing agents,so it had higher sensitive to impurities.In order to ef‐fectively ensure the quality of the coating,the influence of Fe^(2+)、Pb^(2+)、Cu^(2+)and other common metal im‐purities on the morphology,corrosion resistance and grain orientation of the coating were studied by three-dimensional video microscope,electrochemical testing in this paper.The results showed that the iron impurity within the concentration of 0.05 mol/L had no obvious effect on the appearance of the zinc coating,but it would reduce the corrosion resistance of coating and inhibited the growth rate of zinc in the direction of(110).When the concentration of copper ions was greater than 0.01 mol/L,the appear‐ance quality and corrosion resistance of the coating were reduced,the strength of(110)crystal plane of zinc coating is reduced and the strength of(100)and(101)crystal planes was increased.If the content of lead ion was up to 0.001 mol/L,it would greatly affect the appearance and corrosion resistance of the coating,meanwhile it also reduces the strength of(110)crystal plane of zinc coating.