Characterisation of nanometric chromium coatings in metal–polymer composites

Abstract

Electrolytic chromium-coated steel (ECCS) plates are surface protected by a semi-crystalline polyethylene terephthalate (PET) polymer coating that provides mechanical and corrosion resistance properties. At the interface level, the steel is protected by a nanometric electrolytic chromium-based coating that chemically binds with the PET layer. However, axial deformations of the composite alter the chromium oxide layers, due to manufacturing surface discontinuities and the existence of detachment areas, producing adhesion failures, as well as changes in the surface and interfacial morphology of the composite, which limit its functionality. This study evaluated the correlations between delamination areas and uniaxial deformations, and assessed the effect on the chromium layers concerning protection and adherence. The results produced delamination maps, which showed the formation of microcracks on the chromium coatings, and indicated the changes that weakened the metal-polymer chemical bonds that consequently decrease the potential performance of industrial applications such as food containers.

A bulk and localised electrochemical assessment of epoxy-phenolic coating degradation

“…Under-film water accumulation can occur significantly at substrate discontinuities produced during the electrodeposition and the coil rolling process [51,52]. Grain boundaries impurities, micro-cracks, metal oxide pores and Lüders bands formations are all reasons for insufficient polymer bonding [53,54].…”

The Influence of the Roll-Laminating Process on the Bonding Quality of Polymer-Coated Steel Interface

“…The cladding PET film came from Shanghai Baowu Steel Co., Ltd (Shanghai Baowu Steel Co., Ltd, Shanghai, China). The TFS material has a three-layer structure in the thickness direction, which are strip steel, a metallic chromium layer, and a hydrated chromium oxide layer [6,7,25], as shown in Figure 1. The thickness of the hydrated chromium oxide is 135 mg/m 2 .…”

Effects of current frequency on the MAO coatings on AA7050

“…The fused alumina is 'sprayed' from the discharge channel and is rapidly solidified by the chilling action of the electrolyte. The molten oxide inside the ceramic layer is ejected from the discharge micro-pores the characteristic morphology of the solidification [13][14][15][16][17][18][19], as shown in the circle. It is apparent that in Figure 1(a), the pore diameter of the MAO coating is large, which is due to the continuous breakdown discharge of the weak surface of the MAO coating.…”