Effect of trivalent chromium based treatment on the protective properties of steel coated with polymeric film

Abstract

Three main requirements are mandatory in order to achieve optimal quality in canned food: adequate processing of the product, definition of the preserving method, and a correct alloy for the deposit. Lacquer coatings are applied on food cans to enhance corrosion protection and also with decorative purposes. In this investigation, steel coated with a Cr3+ based treatment layer and polyethylene teraphtalate polymeric film (PET), applied by coextrusion, was characterized by electrochemical impedance spectroscopy (EIS) measurements, in NaCl 0.5 M solution, to evaluate the coating corrosion resistance in this environment. The experimental results showed that this new material (tin free) has good corrosion resistance regardless of the porosity found in the polymeric film, indicating that it can be a non-polluting alternative to replace tinplate and hexavalent chromium conversion layer in the food industry, being compatible with the packed product.