Synergistic effect of a one-pot synthesised kaolinite–cerium melamine cyanurate hybrid for an improved metal protective coating

Abstract

This paper presents the cerium–melamine cyanurate (CeMC) complex as an anticorrosive pigment prepared by one-pot synthesis. Further, kaolinite is integrated to prepare KCeMC to improve the barrier performance of the anticorrosive coating. The effectiveness of the synthesised pigment-loaded epoxy coatings was assessed using electrochemical impedance spectroscopy in a 3.5 wt% NaCl solution. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) confirmed the release of the cathodic inhibitor Ce³⁺, which forms a protective layer over defective areas of the coating. A five-fold increase in the initial coat resistance was observed compared to the pristine epoxy, as measured by electrochemical impedance spectroscopy (EIS). A 1 wt% KCeMC loaded epoxy coating reveals better durability among all the synthesised pigment loaded coatings. The impedance results exhibited remarkable long-term durability, maintaining a high coating resistance of 7.70 × 10⁹ Ω cm² after 2 months of immersion in a saline medium. The improved protective properties of the epoxy coating containing KCeMC are attributed to the synergistic effects of cerium inhibition along with the barrier performance provided by kaolinite and melamine cyanurate.