Enhancement of Anti-Corrosion Performance of Epoxy Coatings on Magnesium Alloys Using 8-HQ/ZIF-8@PDA Smart Nanocontainers

摘要

This study presents the construction of a smart nanocontainer system, in which 8 -hydroxyquinoline (8 -HQ) is encapsulated within zeolitic imidazolate framework-8 (ZIF -8), followed by surface polymerization with polydopamine (PDA). This nanocontainer was subsequently integrated into an epoxy resin to develop a novel anti-corrosion and self -healing epoxy coating for magnesium alloys. Experimental results demonstrate that ZIF -8, with its highly ordered microporous structure, effectively adsorbs and embeds the corrosion inhibitor 8 -HQ. In NaCl solution containing extracts from 8-HQ@ZIF-8/PDA particles, the low-frequency impedance of the sample was 3.5 times higher than that in blank saline, and the charge transfer resistance (Rct) reached 5598 Ω/ cm2 , significantly exceeding the Rct value of 168 Ω/cm2 for the blank saline sample. This substantial improvement highlights the corrosion inhibition properties of 8 -HQ/ZIF-8@PDA particles, thereby providing excellent anti -corrosion and self -healing perfor mance for magnesium alloys. Additionally, PDA, rich in hydrophilic hydroxyl and amino functional groups, serves as a superior adhesive material, capable of repairing micro -pores and cracks in the coating, enhancing the interfacial compatibility between the nanocontainer and the epoxy coating. Electrochemical impedance spectroscopy (EIS) analysis indicated that the low -frequency impedance (|Z| 10 mHz ) of the 8 -HQ/ZIF-8@PDA epoxy coating remained greater than 2×107 Ω·cm2 even after 50 days of immersion. Furthermore, after 45 days of salt spray testing, the surface of the epoxy composite coating containing 8 -HQ/ZIF-8@PDA remained intact without any corr osion spots, underscoring the coating's exceptional barrier properties and long -term corrosion resistance. This study provides a promising solution for the anti-corrosion protection of magnesium alloys.