Inhibition properties of anticorrosion pigment based on a natural montmorillonite in epoxy coating on steel

Environmentally friendly anticorrosion pigments for paint coatings based on the natural montmorillonite mineral modified with zinc cations and phosphate anions were obtained by two-stage liquid phase ion exchange. It is established that the corrosion resistance of steel 20 increases in the acid rain environment with the addition of modified Zn/Р-montmorillonite using the potentiodynamic polarization method. The inhibiting efficiency of Zn/Р-montmorillonites depends on the modification, namely, the concentration of the Na3PO4 solution, and increases in the order: 0.005 M < 0.5 M < 0.05 M. The modified montmorillonite was introduced into an epoxy coating on steel. The 20 wt% content of Zn/Р-montmorillonite increases almost 6 times the protective properties of the coating, which is confirmed by the results of electrochemical impedance spectroscopy. This is associated with an improvement of barrier properties and the formation of a protective film based on zinc hydroxides and iron phosphates in defects of epoxy coating on steel surface.