EBS-TA@ZIF-67 Heterostructured Fillers for Enhanced Corrosion Protection and Fire Resistance of Waterborne Epoxy Coatings

Abstract In this work, a tannic acid-functionalized EBS-TA@ZIF-67 (BTZ) heterostructure was fabricated via in situ growth of ZIF-67 onto etched basalt scales (EBS) premodified with tannic acid (TA). Subsequently, the as-prepared BTZ was incorporated into the waterborne epoxy (WEP) to formulate the composite coating. It is found that the resulting composite coating, containing only 0.4 wt % BTZ, exhibits substantially enhanced overall performance. Electrochemical testing reveals that after 42 days of exposure to 3.5 wt % NaCl solution, the |Z0.01 Hz| value of the 4-BTZ/WEP coating increases by nearly 2 orders of magnitude relative to the neat WEP coating, highlighting its superior barrier capability. Furthermore, the peak heat release rate (PHRR) of the composite coating declines by 13.5% compared with the pristine WEP, reflecting markedly improved fire safety. This study demonstrates that the synergistic integration of basalt-derived scaffolds with ZIF-67 provides a viable pathway toward waterborne epoxy composite coatings with exceptional corrosion resistance and flame retardancy.