Effect of the curing agent DETA and its interaction with a rare earth carboxylate as corrosion inhibitor in a hybrid silica-epoxy formulation

Sol–gel based coatings are used to protect metals from corrosion. They offer a barrier to the electrolyte penetration, but they do not provide active corrosion protection. Therefore, corrosion inhibitors are often added to sol–gel formulations to improve the overall corrosion behavior. Sol–gel-based coatings typically require relatively high temperatures to be properly cured, which supposes high energy consumptions and might damage some of the precursors of the formulation, including corrosion inhibitors incorporated to improve the coating’s properties. In this study, the effect of diethylenetriamine (DETA) as a curing agent, and yttrium 4-hydroxy cinnamate [Y-(4OHCin)₃] as corrosion inhibitor, on the chemistry and corrosion performance of a hybrid silica-epoxy formulation are investigated. Solid nuclear magnetic resonance and attenuated total reflectance Fourier transform infrared spectroscopy are carried out to analyze the influence of the curing agent and the corrosion inhibitor on the chemical structure of the coating. The corrosion performance is assessed by means of electrochemical impedance spectroscopy, and the results are evaluated considering the chemical study and the interaction between the different compounds.