Corrosion resistant coating with passive protection and self-healing property based on Fe3O4-MBT nanoparticles

This work synthesized novel Fe 3 O 4 nanoparticles loaded with 2-mercaptobenzothiazole corrosion inhibitors (Fe 3 O 4 -MBT NPs), which possessed not only photothermal conversion property but also corrosion inhibition ability. The loading percentage of MBT inhibitors in the Fe 3 O 4 -MBT NPs was 9.69 wt.%. The obtained Fe 3 O 4 -MBT NPs were incorporated into a shape memory epoxy coating to achieve passive protection and self-healing property. The passive protection property of intact Fe 3 O 4 -MBT/epoxy coating was assessed using electrochemical impedance spectroscopy (EIS) measurement during immersion in 3.5 wt.% NaCl solution. The low-frequency impedance modulus at 0.01 Hz of the composite coating containing 3 wt.% Fe 3 O 4 -MBT NPs was approximately 5 times higher than that of the blank epoxy coating after 240 h of immersion, indicating the superior barrier property of the composite coating. As for the self-healing property, the scratch width on the coating surface could narrow from 80 µm to ∼5 µm after near-infrared (NIR) light irradiation for 30 s, which was ascribed to the excellent photothermal conversion property of Fe 3 O 4 NPs. EIS results verified that both the scratch closure triggered by the photothermal conversion of Fe 3 O 4 NP and the release of MBT inhibitors are beneficial for the suppression of corrosion activity within the coating scratch. The Fe 3 O 4 -MBT/epoxy coating with outstanding passive protection and self-healing property holds great potential to achieve long-term corrosion protection.