Avaliação do desempenho da proteção contra corrosão de revestimentos epóxi com adição de lignina por meio de ensaios acelerados e de corrosão atmosférica

Abstract

Carbon steel structures are subject to the corrosion process when exposed to the atmospheric environment, and this process becomes even more intense in the presence of marine and industrial environments. Coal tar (AH) based epoxy coatings are used for application in various industrial branches, such as oil/gas, to prevent or reduce corrosion of carbon steel structures. In some countries, the use of AH is prohibited due to its carcinogenic, toxic and bioaccumulating activity. In view of this, this work proposes the use of an epoxy resin added with lignin, a by-product from the pulp and paper industry, as an alternative to an AH-free organic coating. In this project, immersion tests in saline solution (3.5% NaCl), atmospheric corrosion tests in urban and marine-industrial environments and accelerated corrosion tests in saturated humidity and saline mist chambers were performed on organic epoxy coatings added with lignin, in the concentrations of 7.5% and 15%, developed by a previous study, to obtain information on the corrosion protection behavior of these coatings. In the implemented methodology, sets of coating samples DGEBA (used as control samples), DGEBA/7.5% Lignin and DGEBA/15% Lignin were used for each assay. The monitoring of the coatings performance was performed using the electrochemical impedance spectroscopy (EIE) technique. The coatings added with lignin showed satisfactory performance in relation to corrosion protection, compared to DGEBA, with emphasis on DGEBA/7.5% Lignin, which showed, in all tests, resistance values in the order of 10ˡˡΩ .cm² , capacitive response predominance and low degradation, while DGEBA/15% Lignin showed significant results only in specific environments.