Self-healing behavior of Epoxy-based Double-layer Nanocomposite Coatings modified with Zirconia Nanoparticles

This work reports the self-healing behavior of epoxy reinforced ZrO2 double-layer nanocomposite coatings to alleviate the deleterious effects of corrosion in the oil and gas industry. The corrosion inhibitor (imidazole) and self-healing agent (polyethyleneimine) were separately loaded into zirconia nanocarrier. The epoxy used as the matrix was reinforced with modified Zirconia and applied on pre-treated steel substrate as pre and top layer. The pre-layer was Zirconia modified with imidazole reinforced into epoxy, and the top layer was Zirconia, modified with polyethyleneimine, reinforced into epoxy. Both layers worked independently to provide double protection to the steel substrate. TEM analysis validated that ZrO2 was 15-25 nm in size with spherical morphology. FTIR analysis results confirmed the chemical interactions and bonding among various chemical species. UV-vis analysis proved the pH and time-dependent release of inhibitor and self-healing agent. Self-healing behavior of the double-layer epoxy-based coating was validated through SEM, which revealed the healing of scratched area within 96 h. EIS analysis performed in 0.61 M NaCl solution demonstrated better corrosion protection of double-layer coatings on steel as compared to blank epoxy and single-layer coatings. This improved corrosion inhibition and resistance are attributed to the efficient release of corrosion inhibitors and self-healing agents from ZrO2 nanoparticles in response to the change in the external stimuli. These coatings can be considered a new route for protecting against corrosion in the oil and gas industry and marine applications.