One-step in-situ growth by one-pot method for uniform BTA@ZIF-8 layer to improve the corrosion protection of sol-gel coatings

A facile one-step in-situ growth by one-pot method for uniform BTA@ZIF-8 (1H-Benzotriazole@Zeolitic Imidazolate Framework-8) layer was developed to prepare BTA@ZIF-8/sol-gel composite coatings on the surface of AA2024-T3. Compared to 2MI (2-Methylimidazole), the much stronger adsorption between BTA and Cu-rich phase of aluminum alloy verified by adsorption thermodynamic and density functional theory calculation promoted heterogeneous nucleation of BTA@ZIF-8 crystals and uniform growth of BTA@ZIF-8 layer. The high corrosion protection of 2.6 μm thick BTA@ZIF-8/sol-gel composite coatings, 10⁶ Ω cm² |Z|_{0.01 Hz} after 30 days immersion and no corrosion pit by the naked eye after 60 days immersion in 3.5 wt% NaCl solution, was ascribed to the barrier property resulting from uniform BTA@ZIF-8 layer and pH-induced release of corrosion inhibitors 2MI and BTA from BTA@ZIF-8 particles.