金属包装饮料罐的腐蚀行为研究

发布时间：2019-03-01 10:31

【摘要】：金属包装饮料罐因其密封性好、保质期长而被广泛使用在饮料行业中。而金属包装罐的缺点之一就是易腐蚀。金属包装罐的腐蚀会致使饮料受污染或劣变从而威胁人们的身心健康,食品安全问题也越来越突出。目前,金属包装罐的腐蚀机理尚不明确。因此,研究金属包装饮料罐的腐蚀行为和失效机理,预测金属包装饮料罐的耐蚀寿命,这对于减少食品安全问题的发生具有极其重要的意义。首先,对金属包装饮料罐原材料马口铁在酸性饮料中的腐蚀电化学行为进行了探讨。结果表明,浸泡初期,锡层腐蚀电流密度很高,达到40μA/cm2。浸泡中期,基体碳钢开始暴露出来,仍以锡层溶解为主。浸泡后期,碳钢腐蚀速度为14μA/cm2,其能够承担的耐蚀寿命很短。大约经过1个月的浸泡,锡层完全溶解。研究了酸性饮料罐罐体马口铁和罐底铝之间的电偶腐蚀倾向,结果表明Sn-Al电偶对的电偶电位差为100mV左右,电偶电流为16μA/cm2左右。电偶腐蚀行为以Sn的腐蚀过程为主,属于弱电偶腐蚀行为,可以忽略电偶腐蚀对金属包装饮料罐货架寿命的影响。四种相同工艺生产的马口铁钝化前后耐蚀性能的研究表明本文中使用的马口铁并未进行高效钝化。而采用我们的钝化方法对马口铁进行钝化后,四种马口铁的耐蚀性明显提高,其中F1马口铁钝化效果最为明显,表明我们采用的钝化方法是合理和有效的。镀锡量测定结果表明,F3马口铁镀锡量误差最小。在酸性饮料中彩印铁的耐蚀性研究表明,经过11个月的浸泡后,彩印铁的涂层电阻远大于106Ω·cm2,表明彩印铁环氧酚醛涂层此时仍然具有防护能力：低电位阴极极化加速彩印铁涂层劣化过程与自然腐蚀状态下彩印铁涂层劣化过程具有很好的相关性,表明低电位阴极极化加速方法可以对彩印铁的耐蚀寿命进行预测。其次,在大批次饮料实罐样品的基础上,通过统计分析,建立了以实罐涂层电阻Rc和Fe元素浓度为变量的金属包装饮料罐耐蚀寿命预测模型。该模型属于机理型模型。运用该模型解析了红牛饮料罐防护体系在饮料液作用下逐渐劣化和失效的两个阶段：第一阶段是涂层快速渗水阶段。第二阶段是涂层下渗入介质积累和腐蚀积累阶段。模型的转折参数Rc.tp和[Fe]tp分别表示涂层渗水已到达金属表面的涂层电阻和口味劣化的临界铁元素浓度值。从金属饮料包装空罐加速耐蚀实验结果中可以看出,低电位加速腐蚀试验结果与自然条件下饮料罐涂层失效过程的结果和模型行为一致,表明低电位阴极极化加速涂层失效试验与自然腐蚀试验具有良好的相关性。两者结合可用于预测金属包装饮料罐的耐蚀质量水平,可作为日常检测方法。
[Abstract]:Metal-packed beverage cans are widely used in the beverage industry because of their good sealing and long shelf life. And one of the disadvantages of the metal packaging tank is that it is easy to corrode. The corrosion of metal packaging can lead to contamination or deterioration of drinks, which threaten people's physical and mental health, and food safety problems are becoming more and more prominent. At present, the corrosion mechanism of metal packaging tank is not clear. Therefore, it is of great significance to study the corrosion behavior and failure mechanism of metal-packed beverage cans and to predict the corrosion-resistant life of metal-packed beverage cans, which is of great significance to reduce the occurrence of food safety problems. Firstly, the corrosion electrochemical behavior of metal packed drinking pot raw material tinplate in acidic beverage was discussed. The results show that the corrosion current density of tin layer is very high at the initial stage of immersion, which is up to 40 渭 A / cm2.. In the middle of immersion, the matrix carbon steel began to be exposed, still mainly dissolved in tin layer. At the later stage of immersion, the corrosion rate of carbon steel is 14 渭 A / cm2, and the corrosion-resistant life of carbon steel is very short. After about 1 month of immersion, the tin layer completely dissolved. The galvanic corrosion tendency between tinplate and aluminum in acid beverage tank was studied. The results show that the couple potential difference of Sn-Al pair is about 100mV and the galvanic current is about 16 渭 A / cm2. The corrosion behavior of Sn is mainly in the corrosion process, which belongs to weak galvanic corrosion. The influence of galvanic corrosion on shelf life of metal packaging beverage can be ignored. The study of corrosion resistance before and after passivation of four kinds of tinplate produced by the same process shows that the tinplate used in this paper has not been passivated efficiently. After passivation with our passivation method, the corrosion resistance of four kinds of tinplate was improved obviously, and the passivation effect of F1 tinplate was the most obvious, which indicated that the passivation method we used was reasonable and effective. The results of tin plating show that the error of tinning amount in F3 tinplate is the smallest. The corrosion resistance of color printing iron in acid beverage shows that after 11 months' immersion, the coating resistance of color printing iron is far greater than 106 惟 cm2,. The results show that the color printing iron epoxy phenolic coating still has the protective ability at this time: the low potential cathodic polarization accelerates the deterioration process of the color printing iron coating and the degradation process of the color printing iron coating under the natural corrosion condition has a good correlation with the degradation process of the color printing iron coating under the natural corrosion condition. The results show that the low-potential cathodic polarization acceleration method can predict the corrosion-resistant life of color-printed iron. Secondly, on the basis of a large number of solid beverage can samples, a corrosion-resistant life prediction model for metal packaging beverage cans is established, which takes the concentration of Rc and Fe elements as variables, based on the statistical analysis of the coating resistance of the real cans. The model belongs to the mechanical model. This model is used to analyze the two stages of gradual deterioration and failure of the protective system of Red Bull Beverage Tank under the action of beverage liquid. The first stage is the rapid infiltration stage of coating. The second stage is the accumulation of infiltration media and corrosion accumulation under the coating. The transition parameters of the model, Rc.tp and [Fe] tp, respectively, indicate the coating resistance and the critical iron concentration of poor taste when the coating has reached the surface of the metal. From the experimental results of accelerated corrosion resistance of metal beverage packaging empty cans, it can be seen that the results of low potential accelerated corrosion test are consistent with the failure process and model behavior of the coating of beverage cans under natural conditions. The results show that there is a good correlation between low potential cathodic polarization accelerated coating failure test and natural corrosion test. The combination of the two methods can be used to predict the corrosion resistance quality of metal packed beverage cans and can be used as a routine test method.
【学位授予单位】：中国海洋大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TB484.4;TG172

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