Evaluation of the Anticorrosion Performance of Calcium Phosphate Core/Shell Coatings

Core-shell is a structure for obtaining high-performance, economical, and eco-friendly anticorrosive compounds. Ca-Phosphate core-shell is prepared by depositing an exterior layer of expensive efficient anticorrosive additive phosphates on a bulk of less expensive additive carbonate. The new core-shell was characterized using X-ray diffraction (XRD) and scanning electron microscopy/energy-dispersive X-ray (SEM/EDX) to clarify its structure; the results establish the presence of phosphate ions on the surface of carbonate. After estimation, the different percentages of core-shell were dispersed in an alkyd resin. The corrosion protection performance of core-shell coatings was investigated using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) in 3.5 wt. % NaCl. The PDP and EIS results revealed that core-shell has high anticorrosive properties. The protection efficiencies were calculated to know the best coating concentration. The core-shell has excellent protective efficiencies up to a concentration of 0.5wt%. The efficiencies are 97.4 and 98.9% at 0.5% for EIS and PDP, respectively. Contact angle measurements assessed the hydrophobicity of the coating. SEM illustrated that the protective coating isolates the surface from chloride attack.