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为了进一步提高热浸镀锌层的耐蚀性能,利用化学转化处理方法在热浸镀锌层表面制备了高锰酸盐转化膜。研究了工艺条件对转化膜耐中性盐雾腐蚀性能的影响,确定了最佳工艺为:KMnO4质量浓度20 g/L,处理温度40°C,pH 2.5~3.0,处理时间60 min。采用扫描电镜、能谱、X射线光电子能谱、X射线衍射等技术对转化膜的表面形貌、化学成分及微观结构进行分析。结果表明,高锰酸盐转化膜主要由Zn和Mn的氧化物组成。电化学极化曲线及阻抗谱测量表明,热镀锌层经高锰酸盐化学转化工艺处理后,极化电阻增大,腐蚀电流密度减小,耐蚀性能明显提高。
In order to further improve the corrosion resistance of hot-dip galvanized coating, permanganate conversion coating was prepared on the surface of hot-dip galvanized coating by chemical conversion treatment. The effects of process conditions on the neutral salt spray corrosion resistance of the conversion coating were studied. The optimum conditions were as follows: the concentration of KMnO4 was 20 g / L, the treatment temperature was 40 ° C, pH was 2.5-3.0, and the treatment time was 60 min. The surface morphology, chemical composition and microstructure of the conversion coating were analyzed by scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The results show that the permanganate conversion coating is mainly composed of oxides of Zn and Mn. Electrochemical polarization curves and impedance spectroscopy measurements show that the galvanized layer by permanganate chemical conversion process, the polarization resistance increases, the corrosion current density decreases, the corrosion resistance significantly improved.