Effects of Graphene-Based Fillers on Cathodic Delamination and Abrasion Resistance of Cataphoretic Organic Coatings

Abstract

This study aims to demonstrate the excellent protective performance of functionalized graphene oxide (fGO) flakes in acrylic cataphoretic coatings. The filler content provides an important contribution in improving the chemical and mechanical resistance of the acrylic matrix. The morphology of the fillers was first investigated by optical and electron microscopy, analysing the distribution of the fGO flakes within the polymer matrix. After that, the flakes were added to the cataphoretic bath in different concentrations, resulting in four series of samples. The cathodic delamination of the coatings was assessed with cathodic polarization cycles and with measurements carried out with a scanning Kelvin probe. Finally, the abrasion resistance at the macroscopic and microscopic level was studied by scrub testing and scratching atomic force microscopy analysis, respectively. The incorporation of fGO at the optimized concentration of 0.2 wt.% greatly increases the cathodic delamination resistance of the acrylic matrix, resulting in an effective barrier against the effects of absorbed aggressive substances. Graphene-based fillers also enhance abrasion resistance, thanks to their high mechanical strength. Thus, this work demonstrates the great protective benefits that can be obtained when using fGO flakes as reinforcing fillers in cataphoretic coatings.

Graphene-Based Reinforcing Filler for Double-Layer Acrylic Coatings

“…The cataphoretic layers were reinforced by means of functionalized graphene oxide (fGO) powder, synthetized according to the procedures performed in previous works [ 47 , 58 , 59 , 60 ].…”

“…The first, called C, was deposited from the pure acrylic bath. The second, labelled CfGO, was instead reinforced introducing fGO flakes in the cataphoretic bath following the optimized conditions presented in the previous works [ 47 , 60 ] where the addition of 0.2 wt % of fGO in the cataphoretic bath was proven to significantly improve the protective performance of the acrylic matrix. Therefore, the fGO powder was added into the cataphoretic bath, which was stirred for 30 min with an ultrasound probe to facilitate the distribution of the graphene-based filler.…”

“…This work is inspired by previous results [ 47 , 60 ], in an attempt to create multifunctional coatings, exploiting the different properties of graphene-based fillers. In this sense, we have deposited double layer coatings, each of which has particular functions and properties.…”

“…In fact, the fGO fillers caused an improvement in the corrosion resistance properties of the acrylic coating, together with a strong decrease in the permeability features of the polymer matrix. In addition, the barrier effect introduced by the flakes increased the cathodic delamination resistance of the composite coating, whose surface abrasion resistance was strengthened thanks to the high mechanical resistance features of graphene [ 60 ].…”

“…However, graphene, if properly treated, has proven to be an excellent reinforcing filler, to be used also in cataphoretic processes. These works [ 47 , 59 , 60 ] paved the way for the possibility of adding different types of fillers in cataphoretic baths, exploiting their versatility.…”