Aspectos cinéticos e desempenho anticorrosivo de HDL dopado com inibidor de corrosão

Abstract

The objective of this thesis was to develop layered double hydroxide (LDH) particles with smart action against steel corrosion and to test its performance as pigment in epoxy paint. The methodology consisted of four steps: i) evaluation of anti-corrosion efficiency and selection of corrosion inhibitors; ii) synthesis of inhibitor doped LDH; iii) formulation and performance characterization of LDH pigmented coatings; and iv) study of inhibitor release kinetics by synthesized LDHs. In the first stage, imidazole was selected for its molecular characteristics. In the second stage, two LDHs were synthesized by lamellar reconstruction: HTC-Im and HTCTe-Im. HTC-Im showed higher crystallinity according to XRD, while HTCTe-Im was characterized by the release of a larger amount of imidazole, with faster kinetics, characterized by UV-Vis spectroscopy. For this reason, HTCTe-Im was chosen to be added as pigment in an epoxy paint. In the third step, the performance in the corrosion tests did not point to clear advantages when using HTCTeIm pigment. In the fourth stage, the characterization of the ion exchange properties and the inhibitor release mechanism by HTCTe-Im and HTC-Im were performed. The HTCTe-Im + HTC-Im mixture was found to show interesting synergy, HTCTe-Im released faster and higher amounts of imidazole. HTC-Im has captured more chloride through the ion exchange mechanism.