Cu-Gr-TiO2 Ternary Nanocomposite for the Application of Anticorrosion Coating: Synthesis, Characterisation and Anticorrosion Properties

Chng, Sook Ling (2022) Cu-Gr-TiO2 Ternary Nanocomposite for the Application of Anticorrosion Coating: Synthesis, Characterisation and Anticorrosion Properties. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

In recent years, nanocomposite coatings have attracted increasing attention in anticorrosion applications due to their unique characteristics. In this study, a novel ternary nanocomposite coating comprised of copper (Cu), graphene (Gr) and titanium dioxide (TiO2) nanoparticles was synthesised via simple one-step electrochemical deposition method. The graphene was prepared by more environmentally friendly electrochemical exfoliation method in a mild and neutral sodium sulphate electrolyte. The synthesised Cu-Gr-TiO2 ternary nanocomposite coating was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The synthesised graphene was also examined by SEM and EDX to ensure the success of exfoliation process. SEM revealed that the incorporation of graphene and TiO2 nanoparticles facilitated denser and more compact coating surface with less micropores. EDX showed the evidence of the formation of graphene and TiO2 nanoparticles with copper matrix. The XRD analysis also confirmed the presence of copper, graphene and TiO2 in the composite coating. TGA demonstrated high thermal decomposition stability of Cu-Gr-TiO2 composite which was attributed to the high decomposition temperature of copper and TiO2 nanoparticles. Peel-off test indicated that the incorporation of TiO2 nanoparticles improved the adhesion strength of copper coating on the mild steel surface. The anticorrosion performance of the Cu-Gr-TiO2 composite coating in acidic and saline environment was evaluated by salt spray test, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization scan. As compared to uncoated mild steel, pure Cu, Cu-Gr, and Cu-TiO2 binary composite coatings, Cu-Gr-TiO2 ternary composite coating was proved to possess the best corrosion resistance due to the synergistic effect of both graphene and TiO2 nanoparticles. In addition, Cu-Gr-TiO2 composite coating offered higher corrosion resistance in sodium chloride solution than in sulphuric acid solution. In salt spray test, Cu-Gr-TiO2 composite coating provided corrosion protection on mild steel with the efficiency of 47.73%. EIS demonstrated increased polarization resistance (Rp) of Cu-Gr-TiO2 composite coating up to 82.29% and 150.02% in 2% H2SO4 and 5% NaCl solutions respectively. Lastly, potentiodynamic polarization scan showed improved corrosion protection efficiency for Cu-Gr-TiO2 composite coating up to 45.45% and 64.10% in 2% H2SO4 and 5% NaCl solutions respectively.