Estudo de revestimentos anticorrosivos do tipo epóxi novolac à base do líquido da casca da castanha do caju

Abstract

Carbon steels are very susceptible to corrosion in the most diverse ways and the marine environment can be considered one of the most aggressive environments for these metals. Since it is necessary to look for ways to prevent or even mitigate this phenomenon, studies on the efficiency of anticorrosive coatings have been developed and improved over time. Thus, efforts have been made to develop coatings with anticorrosive protection capacity and that are biodegradable, ecologically friendly coatings. The coatings synthesized from cashew nut shell liquid (LCC), which are the coatings object of study in this work, are formulations with the addition of 25 %, 50 % and 75 % of LCC (which are the formulations F03, F02 and F01 respectively), which are one of these alternatives. As part of the methodology, atmospheric exposure tests were carried out in an urban environment, immersion in saline solution (3.5 % NaCl), and accelerated corrosion tests in saline mist (5 % NaCl) and saturated humidity chambers, in order to make it possible to study the corrosion protection performance of LCC-based coatings and bisphenol A diglycidyl ether (DGEBA)-based coatings, in each degradation condition considered for the evaluation of performance against corrosion. The monitoring of the degradation of the coatings was carried out using the technique of electrochemical impedance spectroscopy in order to obtain the responses in terms of impedance modulus. Among the LCC formulations analyzed, the one that obtained the best responses was the formulation with 25 % LCC. It has been shown to perform similarly to the DGEBA-based coating which is the reference coating. With Impedance Modulus values greater than 1 MΩ.cm2, the results obtained showed that the coatings with LCC presented satisfactory and similar performances to the DGEBA coating in terms of anticorrosive protection and exhibited good protective capacity in the environments simulated by the corrosion tests.