Kaolin-supported NiCo-LDH nanocontainers for self-healing and anti-corrosion epoxy coatings

Considerable attention has been paid to the corrosion protection of metals due to economic and environmental issues. Among the available approaches, organic-inorganic coatings remain the most practical and economical barrier technology. Nevertheless, conventional formulations frequently suffer from limited durability, inadequate adhesion, and elevated production costs, which restrict their large-scale deployment in harsh environments. In this study, kaolin served as a substrate for the hydrothermal co-precipitation of NiCo-LDH, resulting in K/NiCoLDH composites. Gallic acid (GA), an organic corrosion inhibitor , was then intercalated into the NiCo-LDH structure to form K/NiCoLDH@GA nanocontainers, which were added to an epoxy matrix to enhance corrosion resistance and self-healing capabilities. Structural characterization demonstrated the effective combination of kaolin and NiCo-LDH, and confirmed GA intercalation into the LDH interlayers. Electrochemical measurements and laser confocal microscopy revealed that K/NiCoLDH@GA effectively inhibited the corrosion of Q235 steel by providing both barrier protection and active ion exchange.The prepared K/NiCoLDH@GA/EP coating was further evaluated through long-term electrochemical tests in a simulated seawater environment, showcasing sustained protective performance. To examine self-healing behavior, an artificial scratch was introduced on the coating surface , and the repair process was monitored via scanning Kelvin probe (SKP). Results indicated that the release of GA from the nanocontainers significantly reduced localized corrosion at the defect site . Overall, the K/NiCoLDH@GA nanocontainer system offers a promising, cost-conscious pathway for designing robust and eco-friendly corrosion-resistant epoxy coatings in demanding marine environments. • A hydrothermal co-precipitation method is used to integrate NiCo-LDH onto kaolin, forming a robust nanocontainer framework. • K/NiCoLDH@GA achieved an inhibition efficiency of up to 92.6 %, effectively protecting Q235 steel in saline environments. • Embedding K/NiCoLDH@GA in an epoxy matrix significantly improves both the barrier and self-healing properties, maintaining prolonged coating integrity.