Enhancing Corrosion Inhibition Performance of Steel Bars with Modified MgAl-NO₂-Layered Double Hydroxide Preparation Methods

This study focuses on the synthesis of MgAl-NO₂-layered double hydroxides (LDHs) using different methods and evaluates their effectiveness as corrosion inhibitors for carbon steel in marine concrete exposed to chloride ions. By comparing the co-precipitation, ion exchange, and calcination–rehydration methods, the corrosion resistance properties of the LDHs in simulated concrete pore solutions were evaluated. X-ray diffraction analysis and electrochemical tests were conducted to analyze the LDHs’ behavior during chloride ions sorption. Results showed that the co-precipitation method synthesized LDHs with the highest chloride sorption capacity at 2.73 mmol/g, while the ion exchange method exhibited superior anti-corrosion performance on carbon steel, along with the highest crystallinity levels. The LDHs prepared can be directly added to marine engineering concrete as an additive to provide rust inhibition for the steel. Overall, this study provides insights into the development of new steel corrosion inhibitors, which could be used in marine structures, e.g., marine concrete. It also recommends a co-precipitation method with potential for industrial-scale production and cost-effectiveness.