应用电化学阻抗谱(EIS)技术,结合扫描电镜(SEM)、能量散射X射线谱(EDS)、X射线光电子能谱(XPS)、扫描探针显微镜(SPM)等表面分析技术,研究了镀锡薄钢板在功能饮料中的腐蚀过程并探讨了腐蚀机制.结果表明:浸泡前期,EIS低频阻抗模值的增加与前31h镀锡薄钢板表面形成的腐蚀产物膜有关;随着浸泡时间的增加,EIS低频阻抗模值有所下降,这与腐蚀产物膜的部分脱落以及暴露的基底金属碳钢的腐蚀有关.镀锡薄钢板在功能饮料中浸泡24天后其表面的腐蚀产物膜由外层的富锡层和内层的富铁层组成,XPS结果表明其成分主要是Sn(Ⅱ)/Sn(Ⅳ)与柠檬酸阴离子及Fe(Ⅲ)与柠檬酸阴离子组成的化合物,其腐蚀类型主要是功能饮料中的有机酸对镀锡薄钢板的腐蚀.
In this paper,the corrosion process of a tinplate in a functional beverage was investigated using electrochemical impedance spectroscope (EIS),scanning electron microscopy (SEM),energy dispersive X-ray spectroscopy (EDS),scanning probe microscopy (SPM),and X-ray photoelectron spectroscopy (XPS),and a corrosion mechanism is proposed.We conclude that an increase in the impedance modulus at low frequency is due to the corrosion product forming on the surface of the tinplate over the first 31 h.With an increase in the immersion time a decrease in the impedance modulus at low frequency is due to the detachment of the corrosion product and the corrosion of the carbon steel substrate.X-ray photoelectron spectroscopy (XPS) results show that the corrosion product is mainly composed of a Sn(Ⅱ)/Sn(Ⅳ) citrate complex or an Fe(Ⅲ) citrate complex.Furthermore,the corrosion product film is first enriched with Sn and then enriched with Fe after immersion in functional beverage for 24 d.We propose that the tinplate is mainly corroded by the organic acids that exist in functional beverages.