开路电位测量法评价镀锌层三价铬钝化膜的耐蚀性  

Evaluation on corrosion resistance of trivalent chromium passivated zinc plating coating by measuring open-circuit potential

作　　者：黄美玲[1] 吴育忠[1] 李伟善[1] 马冲 左正勋 

机构地区：[1]华南师范大学化学学院,广东广州510006 [2]佛山南海美德耐化工原料有限公司,广东佛山528247

出　　处：《电镀与涂饰》2008年第9期29-31,共3页Electroplating & Finishing

摘　　要：用钝化剂TRI-V120、TRI-V121和SpectraMATETM25分别对碱性无氰镀锌层进行钝化,考察了钝化层在不同pH的1%(质量分数)NaCl溶液中的开路电位随时间的变化。结果表明,开路电位变化受溶液pH的影响。在pH=3时,镀锌钝化层的开路电位随时间呈规律性变化:开始电位较高,反映了完整钝化层的电极电位;随后逐渐变负,反映了钝化膜的溶解过程;最后处在锌的电极电位范围,反映了钝化膜已经完全溶解。对比盐雾试验结果后发现,从钝化膜电位变化到锌电极电位所需的时间能够反映钝化膜的稳定性,即时间越长,耐蚀性能越好。因此,开路电位测量法能够快速评价镀锌钝化层的耐蚀性。Cyanide-free alkaline zinc plating coatings were passivated with three passivators TRI-V 120, TRI-V 121 and SpectraMATETM 25, respectively. The variation of opencircuit potentials of the passivation films with time was studied in 1% （mass fraction） NaC1 solutions at different pHs. The results showed that the open-circuit potential vs. time curves are affected by pH. The variation of open-circuit potential with time is regular at pH 3. At the beginning, the potential is high, indicating the existence of a complete passivation layer on zinc surface. Then the potential decreases with time, which indicates the nearly dissolution process of the passivation layer. Finally, the potential reaches a value that is close to the electrode potential of zinc and slightly changed with time, which indicates the complete dissolution of the passivation layer. As compared with the results of neutral salt spray （NSS） test, the time for the potential change from passivation layer to zinc reflects the stability of the passivated zinc plating coating. The longer the time elapses, the better corrosion resistance of passivation layer is. Therefore, the measurement of open-circuit potential can be used to evaluate the corrosion resistance ofpassivated zinc coating simply and effectively .

关 键 词：镀锌 三价铬钝化 耐蚀性 开路电位 

分 类 号：TG178[金属学及工艺—金属表面处理]