Corrosion behaviour of zinc coated with composite silica layers incorporating poly(amidoamine)-modified graphene oxide

The aim of the paper is to carry out a detailed investigation of the effect of graphene oxide-poly(amidoamine) (GO-PAMAM) incorporated in silica matrices on the corrosion behaviour of zinc. GO was modified with PAMAM dendrimer in order to improve its dispersion in the silica coatings prepared on zinc by dip-coating. Morpho-structural and physico-chemical characterization of the graphenes were made by FT-IR and Raman spectroscopy, TEM, and XRD. After incorporation, the effect of graphenes on the anti-corrosive performance of silica-coated zinc was investigated by electrochemical impedance spectroscopy. The results revealed that GO-PAMAM nanosheets dispersed in silica matrix significantly improved the corrosion resistance of the coatings. The polarization resistance R p increased from 680 to 2489 kΩ cm 2 . The performances of SiO 2 -GO-PAMAM coatings were compared with those of SiO 2 coatings incorporating GO, reduced graphene oxide (rGO), and 3-aminopropyl triethoxysilane (APTES)-modified GO. The influence of silica sol-ageing of the composite coatings was also investigated, as the polycondensation plays an important role in its anti-corrosive properties. The morphology of the composite coatings was examined by SEM, and their wettability by contact angle measurements. The protection offered by the SiO 2 -GO-PAMAM composite material is the leading. This can be associated with the GO-PAMAM’s high oxidation degree, low electrical conductivity, and by the fact that reduces the penetration of the electrolyte into the silica/zinc interface.