热浸镀锌层表面偏钒酸盐–氟锆酸复合转化膜的研究  

Study on metavanadate–hexafluorozirconic acid composite conversion coating on hot-dip galvanizing coating

作　　者：许乔瑜[1] 孙霞[1] 

机构地区：[1]华南理工大学材料科学与工程学院,广东广州510640

出　　处：《电镀与涂饰》2014年第16期685-689,共5页Electroplating & Finishing

基　　金：广东省教育部产学研结合项目(201213091100312);中央高校基本科研业务费资助项目(2012ZM0011)

摘　　要：在热浸镀锌层上获得了一层连续、致密的偏钒酸盐–氟锆酸复合转化膜。分析了工艺参数对膜层耐蚀性的影响,确定了成膜的最佳工艺条件为:NaVO3 5.0 g/L,H2ZrF6 6.0 g/L,pH=1.5,成膜时间20 min。采用扫描电镜、能谱仪研究了膜层的微观形貌和元素组成,通过中性盐雾试验及电化学方法测试了膜层的耐蚀性能。与未经处理的热浸镀锌层相比,偏钒酸盐–氟锆酸复合转化膜的盐雾腐蚀面积明显减少,电化学阻抗值显著增大,腐蚀电流密度大幅降低。当成膜时间为20 min时,试样表现出最佳的耐蚀性能,并超过了单纯偏钒酸盐转化膜。A continuous and compact metavanadate- hexafluorozirconic acid composite conversion film was obtained on hot-dip galvanizing coating. The effects of process parameters on corrosion resistance of the composite coating were analyzed. The optimal film-forming conditions were determined： NaVO3 5.0 g/L, H2ZrF6 6.0 g/L, pH 1.5, and time 20 min. The micro-morphology and elemental composition were studied by scanning electron microscopy and energy-dispersive spectroscopy. The corrosion resistance of the composite conversion coating was valuated by neutral salt spray （NSS） test and electrochemical methods. The metavanadate-hexafluorozirconic acid composite conversion film features less corrosion area after NSS test, higher electrochemical impedance, and smaller corrosion current density as compared with the hot-dip galvanizing coating. The composite coating formed by treating for 20 min presents the best corrosion resistance, and superior to a pure metavanadate conversion coating.

关 键 词：热浸镀锌 氟锆酸 偏钒酸盐 复合转化膜 耐蚀性 

分 类 号：TG174.443[金属学及工艺—金属表面处理] TG178[金属学及工艺—金属学]