Multifunctional coatings made by addition of functionalized graphene oxide flakes in cataphoretic electrodeposition process

Graphene is a material object of studies in the field of composite materials, exploiting its excellent electrical, thermal and mechanical properties. In recent years it has been attracting a strong interest in the organic coatings, as it allows to create multifunctional layers. Graphene flakes, in fact, can act as a barrier to the passage of aggressive ions, improving the corrosion protection of the coating, and at the same time increasing the conductivity of the organic layer. In this work the cataphoretic electrodeposition process was used for the realization of coatings, as this method guarantees to obtain layers with good adhesion properties, in a simple and economic way. The graphene, as raw material, has been subjected to nitric acid oxidation treatment and functionalized with organosilane, to get a good dispersion in the acrylic cataphoretic bath. The samples’ morphology was observed under optical and electronic microscope, to study the possible defectiveness of the coatings. The behavior in an aggressive environment was evaluated by exposing the samples in salt spray chambers and their corrosion resistance properties were verified through electrochemical impedance spectroscopy measurements. The process parameters, as well as the concentration of functionalized graphene oxide inside the cataphoretic bath, have been optimized, obtaining composite coatings with excellent corrosion resistance properties. It has been verified that the graphene, if properly oxidized and functionalized, allows to improve the properties of the polymer matrix in which it is dispersed. The presence of graphene in the cataphoretic coating allows to obtain a better behavior in an aggressive environment and high guarantees from the point of view of the protection of the metallic substrate.