Desenvolvimento do revestimento epóxi/óxido de grafeno para aplicação em barra roscada

Abstract

The present work presents the investigation of the anticorrosive, tribological and hydrophobic properties promoted by the addition of graphene oxide (GO) in an epoxy matrix for application in threaded bars. In this context, the GO produced by CTNano/UFMG was characterized according to its physical-chemical and morphological characteristics and used to prepare a nanocomposite with the resin derived from the monomer diglycidyl Bisphenol A Ether (DGEBA). Three GO concentrations were tested in the epoxy system (0.1; 0.25; 0.5% m/m) and the nanocomposites were prepared via roller mill. The presence of GO in the epoxy promoted a 23°C increase in the thermal stability of the reference system (pure epoxy processed in the same way as the nanocomposites). However, studies using the differential scanning calorimetry (DSC) technique have shown a decrease in the glass transition temperature of the system with the incorporation of GO. XPS analyzes were carried out to study the interaction between DGEBA and GO and confirm the presence of the nanomaterial in the formulation. The behavior of the systems from traction and flexion mechanical requests were evaluated and the traction results show similarity between the systems under study. On the other hand, the formulation developed for the nanocomposite presented a behavior 52% more tenacious in bending conditions compared to the reference system. The coated threaded rods were initially morphologically evaluated and the homogeneity and integrity of the coatings were verified. The wettability test performed on the coated surfaces showed an increase of 26° in the contact angle for the more concentrated nanostructured system in relation to the reference. The accelerated corrosion tests in a salt spray chamber also indicated the coating manufactured with 0.5% m/m of GO as the most promising in terms of corrosion protection, demonstrating a 36% decrease in the corroded area in relation to the reference coating. The wear of the coatings was studied through a microscale abrasive wear test, in the Calotest equipment, on the surface of flat plates and showed a 31% decrease in the wear coefficient of the nanostructured system compared to the reference. Finally, the set of results reported in the present work indicated the epoxy/GO system as promising in terms of anticorrosive, tribological and hydrophobicity properties.