Boron nitride and ZIF-67 composite material to improve the long term corrosion resistance of epoxy resin coating

During the solidification, the solvent in the organic epoxy resin coating evaporates, causing micropores and cracks inside the coating, resulting in poor corrosion resistance. To solve the problem, perfluorooctane trethoxy silane (PFTS) was used to modify the cobalt-based organic framework (ZIF-67) loaded with the corrosion inhibitor 2-mercaptobenzothiazole (MBT) to synthesise PHBN-ZIF@MBT composite nanomaterial. Afterwards, this nanomaterial was mixed with epoxy resin to form PHBN-ZIF@MBT composite coating. The PHBN-ZIF@MBT composite has good barrier properties and corrosion inhibitor-releasing ability. The contact angle of the coating increased from 78.35°to 116.8°after soaking, and the adhesion increased by 82.6 %. The electrochemical impedance spectroscopy showed that the PHBN-ZIF@MBT composite coating still had a high impedance of 1.90×108 Ω cm2 at low frequency after 28 days of immersion. It is proved in this work that the excellent corrosion resistance of the coating is attributed to (1) the barrier property of PHBN-ZIF@MBT composite; (2) the controllable release of MBT disregarding the change of pH; (3) ZIF-67 increasing the cross-linking density through its catalytic activity of curing epoxy resin.