Study on CePO4 Modified PANI/RGO Composites to Enhance the Anti-Corrosion Property of Epoxy Resin

This manuscript presents a modification method by using nanofillers for simultaneously improving the barrier and corrosion inhibition in epoxy coatings. In this method, polyaniline (PANI) nanofibers are first grown on reduced graphene oxide (RGO) using an in situ polymerization reaction, and then cerium phosphate (CePO4) nanograins are directly modified onto polyaniline/reduced graphene oxide (PANI/RGO) composites using a hydrothermal reaction. A new hydrophobic and corrosion-resistant PANI/RGO/CePO4 nanocomposite is successfully prepared. Physical and chemical characterization was performed by Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–Vis), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (SEM). PANI/RGO/CePO4 nanomaterials were compounded into epoxy resin and sprayed on Q235 carbon steel, and their corrosion resistance performance was tested by using AC impedance spectroscopy and salt spray tests. The results show that PANI/RGO/CePO4 nanocomposites improve the barrier properties of epoxy resin. In addition, X-ray photoelectron spectroscopy (XPS) before and after corrosion showed that the cerium ions and phosphate ions released from CePO4 in the composite had a corrosion inhibition effect. It forms cerium oxide and iron phosphate corrosion inhibition films on mild steel and cuts off direct contact between the electrolyte and the substrate. This nanomaterial-loaded epoxy coating can greatly improve the composite's anti-corrosion ability.