Active and passive corrosion protection coating based on NaY zeolite

The coating of a surface with organic material is the simplest and most effective method to prevent metal materials from corrosion. However, pure resin coatings are prone to corrosion, as corrodents can penetrate the metal surface via micropores. Moreover, passive corrosion resistance, achieved by adding a filler to a coating to lengthen the penetration path of the corrodent, is not sufficient to prevent corrosion. Therefore, the development of coatings with active and passive corrosion resistance properties is necessary to extend the lifetime and enhance the performance of coatings. Herein, a coating with active and passive corrosion resistance properties was designed by loading a NaY zeolite nanocarrier with the corrosion inhibitor benzotriazole (BTA), with a NaY zeolite nanocarrier loading capacity of 7.22 %. The release properties of the resulting NaY@BTA and the corrosion inhibition of BTA released under different pH conditions were investigated. The adhesion strength, contact angles (CAs), and water absorption of the composite coatings were evaluated. The coating with 0.5 % nanocarrier exhibited an adhesion strength of 4.68 MPa, a CA of 84.78°, and the lowest absorbed water content of 1.28 %. The corrosion resistance of composite coatings with different amounts of NaY@BTA was compared, with the electrochemical impedance spectroscopy data of intact and scratched coatings displaying their excellent active corrosion resistance and self-repair properties. After immersion in 3.5 % NaCl solution for 60 days, the low frequency Z_{0.01 Hz} value of EP–PU-0.5%NaY@BTA was 10¹¹ Ω.