Corrosion-resistant composite coatings based on a graphene oxide–metal oxide/urushiol formaldehyde polymer system

Composite coatings were fabricated based on a graphene oxide–metal oxide/urushiol formaldehyde polymer (GO–TiO2/UFP, GO–SiO2/UFP and GO–Y2O3/UFP) system with modifications, and its effectiveness in corrosion protection of metal substrates was demonstrated. First, a GO–TiO2 composite was synthesized using titanium dioxide loading on GO via 3-aminopropyltriethoxysilane (APTES). The GO–Y2O3 composite was synthesized using nano-yttrium oxide intercalating into GO through two different silane coupling agents. The GO–SiO2 composite was synthesized via an in-situ two-step sol-gel process utilizing APTES and tetraethylorthosilicate (TEOS) in an aqueous ethanol solution. The morphology and structure of the GO–metal oxide composites (GO–TiO2, GO–Y2O3 and GO–SiO2) were studied. Subsequently, GO–metal oxides were incorporated into UFP to investigate the composite’s effectiveness in corrosion protection of metal substrates. Compared with GO–TiO2/UFP and GO–Y2O3/UFP, GO–SiO2/UFP showed superior alkali-resistance enhancing performance. Additionally, GO crosslinked with APTES–TiO2 via covalent bonds and the well-dispersed GO–TiO2 in UFP improved the electrochemical corrosion properties of the UFP coatings, most likely due to the obstruction of the diffusion pathways inside the UFP coating matrix, thus preventing the diffusion of penetrating species. It was revealed that the corrosion resistance of GO–TiO2/UFP composite coating was noticeably higher than GO–SiO2/UFP and GO–Y2O3/UFP composite coatings.