Causes of Occurrence and Methods of Prevention of Corrosion of Cans for Food Products

Abstract

The corrosion resistance and material properties of tinplate cans used in a food production facility in Serbia were analyzed to identify the causes of corrosion occurring at the junction between the lid and the can body. The composition of the steel sheet, the tin coating, the type of passive layer, and the organic coating were determined using different analytical methods (XRF, SEM/EDS, and FTIR). Corrosion resistance was determined using the EIS method and by directly immersing the samples with an artificial defect in a diluted NaCl solution. The tin coating was passivated with titanium oxide, to which an organic coating was applied. When filled cans are laced, at the joint between the lid and the can body, the organic coating is locally damaged, and subsequently, steel corrosion occurs. The insufficient thickness of the tin coating (~0.1 µm), and pour wet adhesion of the organic coating are the main causes of steel corrosion in the gap between the lid and the can body. The application of the passive layers that ensure good adhesion of the covering organic coating and application an organic coatings of the new generation that have property of self-healing is probably the promising solution for this problem.