作　　者： ; ; ; ; ; ; ;

机构地区： 湖北省煤转化与新型碳材料重点实验室湖北武汉430081

出　　处： 《材料保护》 2008年第11期28-30,70,共3页

摘　　要： 为提高镀锌钢板的耐蚀性,且替代有致癌作用的六价铬钝化,采用物理共混法以水性丙烯酸树脂和硅溶胶为成膜剂,钼酸盐为缓蚀剂,添加植酸得到了无铬钝化液,并对镀锌板进行了钝化处理。通过中性盐雾腐蚀试验(NSS)确定了该钝化液的最佳组成;应用SEM分析了所得钝化膜的形貌及膜层元素组成;采用极化曲线研究了钝化膜的耐蚀性及耐蚀机理。结果表明:镀锌层经过无铬钝化液处理后耐蚀性明显提高,60hNSS后腐蚀面积仅为5%;钝化还在镀锌层表面形成了一定厚度的保护性膜层;钝化后试样的开路电位[-1054mV(vs SCE)]较未处理过的镀锌层[-1098mV(vs SCE)]有所正移,钝化膜的存在阻滞了锌层腐蚀的阴极过程。 In order to enhance the corrosion resistance of galvanized steel and replace toxic chromate,a chromate - free passivation bath for galvanized steel was formulated by physical mixing, using waterborne acrylic resin latexand colloidal silica sol as the film - forming agent, molybdate as the corrosion inhibitor, and phytic acid as the additive. The optimal composition of the bath was determined based on neutral salt spray tests (NSS). The corrosion resistance and anticorrosion mechanism of the passivation film were studied making use of polarizationcurve tests, while the appearance and element compositionof the passivation film were analyzed using a scanning electronmicroscope. Results showed that the corrosion resistance of the galvanizing coating was considerably increased after being passivated with the passivation fluid, and the percentage of corrodedarea of the passivated galvanizing coating was only 5% after uninterrupted 60 h of NSS. A protective passivation layer of a certain thickness was formed on the galvanizing coating after passivationtreatment, and the passivation layer was capable of retardingthe cathode process of the galvanizing coating, leading to a positive shift of the open - circuit potential from-1098 mV (vs SCE) of the naked galvanized steel to-1054 mV ( vs SCE) of the passivated galvanbizing coating.

关 键 词： 镀锌钢板 无铬钝化 钼酸盐 硅溶胶 极化曲线 耐蚀性

领　　域： [化学工程]