  The present work reports the effect of adding Graphene Oxide (GO) and reduced
Graphene Oxide (rGO) in the corrosion protection provided by a water-borne
resin applied on a galvanized steel substrate. Three concentrations, 0.05, 0.1
and 0.15 (all wt%) were tested. The results were markedly affected not only by
the concentration of particles but also by their nature. Although the zeta
potential values suggested good dispersibility of the particles in the resin,
certain aggregation was observed, mainly in rGO 0.1 wt% and rGO 0.15 wt%
formulations. The electrochemical impedance spectroscopy (EIS) technique
characterised the free films' transport properties. The results suggested that
the aggregation strongly influenced the film morphology. The rGO 0.1 wt% and
rGO 0.15 wt% formulations exhibited percolating pores that facilitated the
electrolyte uptake through the films. The EIS technique was also used to study
the protective performance of the films when applied to the metallic substrate.
The results confirmed the harmful effect of the particle's aggregation. The
results were interesting for the rGO 0.05 wt% system, which displayed
long-lasting protection properties. This performance was explained considering
its good barrier properties and the zinc surface passivation by the generation
of zincite, ZnO.
