Electrochemical, mechanical and adhesive properties of surface modified NiO-epoxy nanocomposite coatings on mild steel

Abstract

The effect of surface modification of NiO (nickel oxide) nanoparticle by (3-Mercaptopropyl) triethoxysilane (MPTES) in the epoxy-NiO nanocomposite coatings on mild steel was analyzed by electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) techniques in seawater. MPTES was treated with the nanoparticle for the proper dispersion and chemical interaction of nanoparticle with the epoxy resin. The introduction of NiO nanoparticle in the epoxy coating enhances the charge transfer resistance (Rct) as well as the film resistance (Rf). The observation of iron dissolution and oxygen consumption was carried out using an appropriate potential at the SECM tip in the NiO modified nanocomposite coated steel. The pure epoxy and epoxy-NiO nanocomposite coated samples were used to study the mechanical, adhesion, and anticorrosion properties. The analysis by field emission-scanning electron microscopy/energy dispersive X-ray analysis (FE-SEM/EDX) displayed the enriched Ni was detected in the nanocomposite coating of steel. The presence of the nano level corrosion product containing Ni was confirmed by focused ion beam-transmission electron microscopy (FIB-TEM) analysis. The high corrosion protection properties of epoxy nanocomposite coatings were due to the formation of complex nanoscale layer and chemical interactions of epoxy resin with surface modified nanoparticle in nanocomposites.