Revestimentos de nanocompósitos de fusion-bonded epoxy com óxido de grafeno reduzido em aço carbono : análises tribológicas e eletroquímicas

Abstract

In this work, the influence of the addition of reduced graphene oxide (RGO) to the Fusion-Bonded Epoxy (FBE) matrix was evaluated. The analyzes of thermogravimetry (TG), spectroscopy in the infrared region with Fourier transform (FTIR), Raman spectroscopy, scanning electron microscopy (SEM) were used to characterize the starting materials. Mixtures of the FBE + RGO system in powders were produced in concentrations of 0.1; 0.3; 0.5; and 1.0% w / w, in a planetary ball mill. The plates were heated in an oven at 204 ° C and the deposited material went through the process of fusion, adhesion and curing on the steel substrate. The curing of the material was evaluated and confirmed through the analysis of differential exploratory calorimetry (DSC), according to the reference standards ISO 21809-1 and CSA Z245.20, with a glass transition temperature (Tg) of approximately 112 ° C. Optical microscopy (OM) was used to verify the presence of agglomerates in the coatings applied on the metal, indicating that the average size of agglomerates was around 5 to 15 μm in diameter. The applied coatings were characterized against adherence and hot immersion tests indicating that the addition of RGO improves the composite's adhesion to the metal, with increases of 95% and 104% for the composites with 0.5% w / w oxide reduced graphene via thermal reduction and expansion in a microwave oven (RGO-ET) and 1.0% w / w reduced graphene oxide via thermal reduction in an oven (RGO-RT), respectively. Abrasion tests were applied to the coatings, obtaining wear reduction of 7% and 11% for composites with 0.3% w / w RGO-RT and 0.5% w / w RGO-ET, respectively. Electrochemical Impedance Spectroscopy (EIE) tests, performed on FBE coatings with the introduction of a drill defect, electrochemically characterized the metal-coating interface for 21 days in saline solution 3.5% w / w NaCl. The EIE showed improvement in corrosion protection for FBE / RGO nanocomposites due to the barrier mechanism promoted by the insertion of the nanocharge.