Anti-corrosion properties of composite inhibiting pigment based on natural calcium silicate and zinc orthophosphate in epoxy coating on aluminum alloy

The results of a study on the anticorrosion properties of a composite pigment based on calcium silicate and zinc orthophosphate, obtained by solid-phase modification in a high-energy planetary ball mill are presented. X-ray energy-dispersive analysis confirmed the presence of silicon, phosphorus, calcium, and zinc in the pigment composition. Electrochemical impedance spectroscopy revealed that introduction of the composite pigment into an epoxy coating on an aluminum alloy significantly enhances its protective properties, particularly under conditions of localized coating damage. The synergistic interaction between the pigment components promotes the formation of a stable protective layer in defect zones, effectively inhibiting the corrosion process. The highest anticorrosion efficiency was observed for the pigment with a wollastonite-to-zinc orthophosphate mass ratio of 2:3, which provided reliable protection for both damaged and intact epoxy coatings during exposure to a 0.1% NaCl solution. The results indicate that the composite pigment stabilizes the barrier properties of the coating and reduces the degradation of the paint system.