Yi Huang,Chenyang Zhao,Yue Li,Chen Wang,Wenlin Yuan,Tao Shen,Jie Liu,Di Cheng,Chunchun Wu,Qianhong Shen,Hongliang Ding,Siyuan Chen,Hui Yang
Integration of both passive and active corrosion-protecting mechanisms is an effective method for endowing sol-gel derived coatings with long-term anticorrosion performance. To provide “smart” functionality for sol-gel coating, a novel self-healing nanocontainer is fabricated via the in-situ growth of 1H-benzotriazole-inbuilt zeolitic imidazolate framework (BTA-ZIF-8) on hydroxylated hexagonal boron nitride nanosheets (BN-OH), which exhibits efficient pH-dependent inhibitor release behavior at both acidic and alkaline media. Electrochemical measurements reveal that sol-gel coating containing the BTA-ZIF-8@BN-OH nanocontainers exhibits superior anticorrosion performance and long-term corrosion protective capability, with |Z| 0.01Hz increased by nearly three orders of magnitude (∼2 × 10 8 Ω·cm 2 ) compared to that of pure sol-gel coating after 28 days of saline solution immersion. In addition, the EIS measurements on sol-gel coating surfaces with artificial scratches show increased impedance values after prolonged immersion in saline solution, indicative of effective active inhibiting effect. This phenomenon is the result of the synergistic effect of both passive and active corrosion protection . The active protection (inhibiting effect) is provided by the on-demand release of inbuilt BTA inhibitor from ZIF-8 frameworks, whereas the passive protection (barrier performance) is achieved through the “labyrinth effect” of BN-OH nanosheets as well as the improved interfacial compatibility of nanocontainers with surrounding sol-gel matrix by surface hydroxylation of h-BN nanosheets. This nanocontainer design offers a facile strategy for fabricating self-healing sol-gel coatings with the exceptional anticorrosion properties.
Chen Wang,Chenyang Zhao,Yue Li,Jie Liu,Di Cheng,Tao Shen,Ji Zhang,Qianhong Shen,Hui Yang
The spatial distribution of functional nanofillers in anticorrosion coatings significantly influences their ability to seal micropores/cracks and enhance self-healing properties. In this study, a novel dual-responsive nanocontainer loaded with the corrosion inhibitor benzotriazole (BTA) was developed for active corrosion protection in waterborne epoxy coatings. The magnetic nanocontainers (Fe 3 O 4 @BTA-ZIF-8) were synthesized via the in-situ growth of BTA-encapsulated zeolitic imidazolate frameworks-8 (ZIF-8) on the surface of anion-modified Fe 3 O 4 nanoparticles. This unique structure endows the nanocontainers with pH responsiveness for controlled BTA release under corrosive conditions. Additionally, under an external magnetic field, the nanocontainers migrate toward the coating/metal interface, increasing the local inhibitor concentration and improving corrosion resistance. Potentiodynamic polarization tests revealed that the nanocontainers achieved an inhibition efficiency of 82.40 % on carbon steel surface after 24 h of saline immersion. Cross-sectional analysis of the composite coatings confirmed the magnetic-field-induced accumulation of nanocontainers at the coating/substrate interface, facilitating rapid and efficient inhibitor release. Electrochemical impedance spectroscopy results further revealed a low frequency impedance value (|Z| 0.01 Hz ) of 1.42 × 10 10 Ω·cm 2 for epoxy coating containing magnetically distributed Fe 3 O 4 @BTA-ZIF-8 nanocontainers after 35 d of saline immersion, over an order of magnitude higher than that of coating without magnetic modulation. Furthermore, the scratched composite coating after magnetic modulation exhibited an improvement efficiency (η) of 165.04 % after 6 h of immersion, compared to only 22.76 % for the non-modulated counterpart. These results confirm the long-term protective performance of Fe 3 O 4 @BTA-ZIF-8 within epoxy coatings under magnetic modulation. This study is the first to introduce a magnetic MOF-based nanomaterial for corrosion protection, demonstrating the potential of epoxy coatings with magnetically directed distribution and pH-responsive inhibitor release.
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