Resumen
Due to the porous surface and hydrophilic nature of epoxy resin (EP), carbon nanotube (CNT) fillers have been utilized to decrease the porosity of EP coatings and increase the resistance to corrosion inducing elements. Unfortunately, CNT has a high tendency to agglomerate, leading to a non-homogeneous dispersion of CNT in the EP coating. Hence, in this study, CNT functionalized by zinc oxide (CNT-ZnO) is evaluated to obtain a well dispersed CNT-ZnO/EP coating with enhanced corrosion resistant properties. First, CNT was pretreated with acid and further functionalized by APTS-ZnO to reduce CNT agglomeration. Subsequently, the CNT-ZnO nanohybrid was incorporated into epoxy resin via solution blending method. The composite formed was then coated on mild steel and cured at room temperature for 7 days, followed by post-curing at high temperature. The functionalization of ZnO with APTS, as well as CNT with APTS-ZnO were characterized using Fourier-Transform Infrared Spectroscopy (FTIR), while the homogeneity of the CNT-ZnO/EP coating was examined using Field Emission Scanning Electron Microscopy (FESEM). Finally, the effectiveness of the corrosion resistant coating was evaluated using the water absorption test, pull-off adhesion test, salt immersion test and electrochemical impedance spectroscopy (EIS). The FTIR analysis concluded that the functionalization of CNT was successful as it displayed functional groups inherent to ZnO-APTS as well as the acid-modified CNT compounds. Furthermore, the FESEM imaging showed a well dispersed CNT-ZnO nanohybrid across the EP matrix, which was further confirmed using energy dispersive x-ray (EDX) analysis and elemental mapping. In addition, water absorption test, salt immersion test, pull off adhesion test and preliminary EIS proved that the incorporation of 0.1 wt% CNT-ZnO into EP matrix successfully enhanced its corrosion protection performance and barrier properties.