With the progress of studies on corrosion of ferrous materials, new materials have emerged to increase corrosion protection efficiency in organic coatings using double lamellar hydroxides.
In this work, a comparative study on the influence of the addition of layered double hydroxides-HDLs, containing NO2- and NO3- anticorrosive inhibitors in the interlaminar layers, in organic coatings based on epoxy resin was carried out. The study was conducted by physicochemical characterization of nanocontentors, electrochemical measurements on coatings and standardized tests. It was evidenced that the HDLs were agglomerates, which may be partially disaggregated into ethanol. The results of Zeta potential corroborated the data of optical and scanning electronic microscopy, showing that the clusters are unstable even if dispersed in ethanol. The results of the drying-cure kinetics of the wet films obtained by the diffuse wave spectroscopy technique showed that the addition of LDH nanocontentors does not interfere with the drying-curing coating mechanism. In the electrochemical measurements the open circuit potential values were similar for both coatings, without and with addition of HDLs, and the values obtained during 180 days of monitoring were close to zero Volts (vs. Ag / AgCl with saturated KCl), indicating high corrosion protection of the epoxy coatings used. It was also found that coatings without LDH exhibit slightly lower impedance values when compared to coatings containing LDH. In all standardized tests, both coatings presented the same performance. In the tensile adhesion test, non-LDH coatings exhibited cohesive failure while HDL coatings exhibit adhesive failure, suggesting that the addition of LDH could aid in greater adhesion of the coating under the metal substrate.