Lima, A. C. ; Martins, A. ; Santos, E. ; BARCIA, Oswaldo Esteves ; Margarit-Mattos, Isabel Cristina Pereira .
Resumo: The objective of this work is to evaluate the anticorrosive properties of epoxy novolac coatings, pigmented with micaceous iron oxide, to which 1% and 5% w / w of three types of montmorillonites (MMTs) were added: a natural calcium (bentonite), a sodium and a sodium with chemical treatment. The literature presents MMT as an inert pigment that would be capable of improving the barrier properties of anticorrosive coatings. In the studied epoxy coating the contribution of MMTs to the barrier action depends on the type and content. The experimental methodology consists of tests of permeability to water vapor, water absorption, immersion test and salt spray. Complementary tests include Foster swelling, mass loss and electrochemical impedance. It was seen that the chemical treatment improved the barrier effect but impaired the adhesion of the coating. It was found that with 5% of any type of MMT, the epoxy coating had underfilm corrosion inhibiting action. It is a moderate action as it does not extend to incision areas. Therefore, MMTs are not inert pigments and, even at low levels such as 5%, can contribute to further improve coating performance that is already considered noble; the epoxy novolac pigmented with micaceous iron oxide.
