金属饮料罐腐蚀行为及其作用机理研究

Corrosion Behavior of Metal Cans for Drinks

用稳态极化曲线和电化学阻抗谱方法研究了镀锡板、彩印铁和实罐的腐蚀电化学行为特征.结果表明,未经钝化处理的镀锡板腐蚀电流密度接近40μA/cm2,而钝化处理后的镀锡板腐蚀电流密度降低至原来的1/10,耐蚀性显著提高.电化学阻抗测试结果表明,与彩印铁相比实罐阻抗模值下降近3个数量级,说明经过一系列制罐加工工艺后涂层的耐蚀性显著下降.因此,镀锡板进行钝化处理以及对罐底收缩部位进行涂层修复、或采用更耐加工型的涂料能够有效提高金属饮料罐的货架寿命.

Metal packaging is an industry sector of rapid development. However, the corrosion of metal cans caused by packaged corrosive drinks may shorten the service life of the cans. It was frequently seen that there were large area with corroded spots even perforations on the shrinkage area of the cans. To find out the causes of corrosion of metal cans and increase its corrosion resistance, a study on corrosion behavior of tinplates, color printing iron and filled cans was made in this paper using steady-state polarization curves and electrochemical impedance spectroscopy. The results indicated that the corrosion current density of the bare tinplate reach 40 μA/cm2, on the contrast, the corrosion current density of the passivated tinplate dropped nearly 10 times. The impedance measurement showed the same results. Electrochemical impedance test of real cans and color printing iron showed that the impedance values of filled cans dropped nearly 1000 times, compared to that of color printing iron, which revealed that after a series of can-making processes the performance of coating was detriorated significantly. It is suggested that the following measures may be the useful for improving the service life of metal cans： the passivation of tinplates or remedy of shrinkage parts of cans after making processes or application of coatings with performance much compatible to the making processes.