Enhanced corrosion resistance and mechanical properties of nanostructured graphene-polymer composite coating on copper by electrophoretic deposition

Composite coating of reduced graphene oxide (RGO) and poly (4-vinylpyridine-co-butyl methacrylate) (PVPBM) on copper was produced by electrophoretic deposition (EPD) technique. The structural and morphological characterizations of the RGO-PVPBM coating were carried out using a Raman spectrometer and a field emission scanning electron microscope, respectively. The thermal stability of the coating was analyzed by thermo-gravimetric analysis, and the corrosion resistance properties were examined by potentiodynamic polarization measurements and electrochemical impedance spectroscopy in 3.5% NaCl solution. At optimal EPD conditions of operating voltage of 5 V and total deposition time of 15 min, a uniform crack-free RGO-PVPBM composite coating is obtained. The microscratch experiment has shown an enhancement in the crack propagation resistance of RGO-PVPBM composite coating up to 3.7 times and adhesive strength increased ~2 times compared to PVPBM coating, thereby making it a potential damage tolerance surface coating on Cu substrate. The potentiodynamic measurements clearly show that RGO-PVPBM acts as a protective coating for Cu in 3.5% NaCl solution. The corrosion inhibition efficiency for RGO-PVPBM coating was calculated to be 95.4% which clearly indicates that the tailored RGO-PVPBM composite is an excellent barrier coating to ion diffusion and corrosive electrolyte with considerably enhanced corrosion resistance.