MIL-88A (Fe) filler with duplicate corrosion inhibitive/barrier effect for epoxy coatings: Electrochemical, molecular simulation, and cathodic delamination studies

Abstract The MIL-88A (Fe) as a MOF based on Fe+3 cations and fumaric acid was fabricated as a corrosion inhibitive filler to achieve a protective coating with duplicate active/passive inhibition properties. The polarization test indicated that the MIL-88A (Fe) saline-based extract had an inhibition effect. The formation of an inhibitive layer was seen in the EIS results for the sample immersed in the MIL-88A (Fe) extract. The slight solubility of MIL-88A (Fe) in the water (122.4 ppm total organic carbon and 2 ppm Fe+3) caused the inhibitive ions' release. The adsorption of release species from MIL-88A (Fe) scaffold on the substrate was confirmed by the theoretical (QM, MC/MD) computations. The EIS and salt spray test results obtained from scratched epoxy coated samples showed the Epoxy-MIL-88A (Fe) coating's active inhibition effect. The pull-off adhesion strength and cathodic delamination resistance were also improved in the presence of MIL-88A (Fe). The adhesion loss of epoxy coatings after 7 days of exposure to the salt spray decreased from 31.4% to 9.4%, respectively. The unscratched samples filled with MIL-88A (Fe) particles showed excellent barrier properties. The breakpoint frequency value declined from 2.4 to 0.8, and the reduction of low-frequency impedance magnitude decreased from 33% to 20%.