Colloquia

Summary

Polymer-coated steels are used in the packaging industry to produce a variety of products, for instance, food cans. In the can-making process, the observation of a damage mechanism that resembles scuffing could limit the process window. The types of wear mechanisms could differ based on the type of coating and also the conditions of the process. A scuffing type wear was observed in the can-making process and the failure mechanism had to be identified and whether or not it was different for the two types of coatings which are named as transparent and white coatings (for ease of identification in the report) used in the can-making production line. The white coatings had a composition of titanium dioxide added to the main (polymer) layer when compared to the composition of the transparent coatings which could give rise to differences in the properties between the two samples. The parameters to simulate the failure were decided based on the parameters like loads, temperatures, and velocities observed in the can-making process. The observed failure types and the layer undergoing failure needed to be studied based on the failure that was observed on simulation of the process in a controlled environment. Scratch testing experiments were performed in the universal mechanical tester and the damaged layers were studied under the SEM to analyze the type of damage observed in both the coatings.

The transparent coating showed adhesive wear in the polymer layer whereas the white coating showed delamination wear between the adhesive layer and the main (polymer) layer. A model was developed to explain the parameters affecting the adhesive wear in the transparent coatings and another model was developed from the DEG model to explain the wear in general in the white coatings due to insufficient data to characterize the adhesive layer. Hence, from these models, it was evident that the failure in the transparent coatings was thermally driven and the failure in the white coatings was mechanically driven.