Impact of graphene nanosheets on adhesion and corrosion performance of reinforced polyurethane coating for aerospace aluminium alloy 2024-T3

This investigation aims to create an integrated multilayer coating system for the surface of aerospace aluminium alloy 2024-T3. A solution-sonication mixing approach was applied to fabricate low-cost and high-efficiency layers. The coating system consisted of three main layers: pretreatment, green epoxy primer (GEP), and polyurethane (PU) top coating layer. To create the pretreatment layer, 50% graphene oxide (GOLMdis) was functionalized using a 50% 3-aminopropyltriethoxy silane coupling agent (SCA). The PU top coating layer was grafted with 1-3% wt. of GOLMdis to improve its resistance to environmental influences. Various analytical techniques such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), and Thermogravimetric analysis (TGA) were used to evaluate the properties of the PU-GO layer. The results confirmed the graft of GOLMdis onto the surface of PU, proving the existence of an interaction between the nanosheets and the polymer. The corrosion resistance performance of the multilayer coating systems was evaluated using electrochemical and adhesion tests. The 50%GO-SCA/Epoxy/2% GO-PU coating system outperforms other coating systems. It exhibited a significant improvement in the real impendence (Zre) by up to 9068 % compared to other coating systems. Moreover, only 5% of the coating was removed during the adhesion analysis. The results confirm the successful incorporation of anti-corrosion graphene oxide fillers into the multilayer coating system for corrosion protection of aerospace alloy 2024-T3.