马口铁三片罐耐腐蚀性能的电化学阻抗评估技术

马口铁三片罐作为食品饮料等的重要包装之一，由于其内容物多具有腐蚀性，罐体部位容易发生腐蚀，这将严重影响食品的感官、口味，严重时甚至使内容物发生变质，如变酸、变臭及罐体穿孔等。因此，研究马口铁三片罐在不同内容物介质中的腐蚀机理以及如何评价涂层体系的耐腐蚀能力，最终确立货架寿命评估体系是制罐行业的一个重要课题。相对于传统的三片罐腐蚀研究方法，电化学阻抗谱（EIS）具有较好的技术优势。EIS技术现已成为研究有机涂层防腐机理与性能的一种主要的电化学方法，一般采用三电极体系，是对研究体系施加一系列小振幅的正弦交流信号，再测量体系的响应信号，得到体系的阻抗、容抗谱，进而利用数学方法和等效电路模型等，可获得体系的多种电化学信息。马口铁三片罐的耐腐蚀性能评价特征参数和临界值范围的确定是需要首先解决的难题，可以采用开路电位、低频阻抗、特征频率、等效电路中的Rf值等进行综合判定。

Electrochemical Impedance Corrosion Resistance Assessment Technique of Three-piece Tinplate Cans

The three-piece tinplate cans are used as one of main beverage and food packaging, due to the corrosive con- tents can-body is easy to set off a corrosion as a result the flavor or appearance of contents are damaged even the contents go off with bad smell, for this reason, it is becoming a important subject in can-making industry to study the corrosion process of the three-piece tinplate can and define the corrosion resistance of coating systems at last, establish standard sys- tems to evaluate shelf life. EIS method have some of evident advantages compared with conventional corrosion study on the three piece can. more and more researchers use it to study the performance and corrosion resistance of epoxy phenolic coating, generally speaking by the way adopting to three electrodes EIS is a kind of method that the sample impose small sinus waves and gain the impedance, capacitance, mathematical method and equivalent circuits would be used in the ex- periment at the attempt of analysing and acquiring various information. The top priority for the corrosion resistance of tin- plate cans is to decide characteristic parameter and frequency range . some parameters are helpful for us to analyse like open circuit potential ,the low frequency impedance, characteristic frequency, Rf in equivalent circuits