Effects of highly crystalline and conductive polyaniline/graphene oxide composites on the corrosion protection performance of a zinc-rich epoxy coating

Abstract

This study reports a new strategy for providing ZRC with enhanced cathodic and barrier protection mechanisms simultaneously. For this purpose, the graphene oxide (GO) nanosheets were modified by highly crystalline and conductive polyaniline (PANI) nanofibers in the form of Emeraldine salt (ES) through an in situ polymerization of aniline in the presence of GO as an oxidant. The aniline polymerization in the presence of GO and the PANI nanofibers deposition on the GO surface were exhibited by Fourier transform infrared (FT-IR) spectroscopy and high resolution-transmittance electron microscopy (HR-TEM). In addition to these the X-ray diffraction (XRD) patterns confirmed the deposition of highly crystalline PANI nanofibers on the GO and between the GO layers. Inclusion of 0.1wt% GO and GO-PANI nanosheets into the ZRC sample remarkably enhanced its corrosion protection performance. Salt spray, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) measurements revealed that both the cathodic protection properties and barrier performance of the ZRC were improved after addition of 0.1wt% GO and GO-PANI nanosheets to the ZRC sample. The most pronounced improvement in the ZRC properties was obtained using GO-PANI. The results obtained from field-emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy and XRD analysis confirmed lower degree of zinc particles oxidation and steel substrate corrosion in the case of ZRC including GO-PANI nanosheets compared to other samples.