Active Corrosion Protection by Nanoparticles and Conversion Films of Layered Double Hydroxides

The active corrosion protection of metallic substrates can be achieved by the addition of corrosion inhibitors to protective coatings. However, direct mixing of inhibitors with coating formulations can lead to important drawbacks, decreasing barrier properties of the coating and diminishing activity of the inhibitor. Nanocontainers for corrosion inhibitors were developed in this work using layered double hydroxides (LDH) as nanocarriers. The LDH were used as nanosized particles, which are then included in a sol-gel hybrid coating, and as a LDH layer directly formed on the metal surface (conversion film) and covered by a sol-gel hybrid layer. Electrochemical impedance spectroscopy (EIS) has been used for evaluation of corrosion protective properties of the coatings. The results show that the LDH with incorporated vanadate inhibitor provide efficient active corrosion protection in both cases.