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.