【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。更多还原

【Abstract】 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.更多还原