Preparation and characterization of a GPTMS/graphene coating on AA-2024 alloy

Highlights: • A KH560/graphene coating was prepared on 2024 aluminum alloy by immersing and curing. • The thickness of the composite coating increased greatly compared with silane coating. • The covalent metallic-siloxane bonds improved the adhesion force greatly. • The laminate structure increased the hardness and declined brittleness of the coating. • The composite coating showed much higher corrosion resistance in NaCl solution. - Abstract: A γ-(2,3-epoxypropoxy) propyltrimethoxysilane/graphene (GPTMS/rGO) coating on AA-2024 aluminum alloy was prepared by immersing the aluminum alloy sample in a silane/graphene oxide solution and curing in oven at 180 °C. Silanol groups were grafted onto graphene oxide sheets during hydrolysis. The graphene oxide was stacked layer by layer through silanol groups. The synthesized coating was characterized with Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectra and scanning electron microscopy. The thickness of the composite coating increased greatly compared with that of silane coating, due to the mutual riveting effect. The covalent metallic-siloxane bonds (AlOSi) improved the adhesion force greatly. The laminate structure of graphene increased the hardness and declined the brittleness over 200 °C. The GPTMS/rGO coating showed good corrosion resistance. In 3.5% NaCl solution the anodic current density of the aluminum alloy sample with GPTMS/rGO coating was reduced by several orders of magnitude compared with those of bare aluminum alloy or the sample with graphene film.