Anticorrosive Behaviors of Epoxy Coating Modified by Hydrophobic Nano-Silica and Graphene on Phosphatized Carbon Steel

Corrosion of carbon steel causes many losses, hazards, and contaminations to our daily life. In this article, epoxy synergistically added with hydrophobic nano-silica and graphene was prepared to provide corrosion protection for carbon steel. Graphene can act as filler to improve the corrosion resistance of epoxy, but the aggregation of graphene severely affects its application. Embedding hydrophobic nano-silica into graphene sheets contributes to the good dispersity of graphene in an epoxy matrix. Besides, SiO₂ can also act as another filler to improve corrosion resistance. Hence, the synergistical addition of hydrophobic nano-silica and graphene into epoxy can provide better corrosion resistance for modified epoxy coating. A scanning electron microscope was used to investigate the microstructures of modified epoxy coating. Coating wettability was measured by a static contact angle measurement instrument. The anticorrosive behaviors of modified coatings were measured by an electrochemical workstation. The corrosion mechanism was analyzed by equivalent circuits simulation. According to the results, the modified coating with impedance of about 10⁸ Ω·cm² (10 mHz) at 100 d immersion still showed excellent anticorrosive performance. In general, epoxy doped with hydrophobic nano-silica and graphene displays better corrosion protection than epoxy without modification.