Electrochemical Investigation into the Effect of Nano-Titania on the Protective Properties of Epoxy Coatings on Mild Steel in Natural Seawater

The effect of introducing nano tinania TiO particles to the epoxy coatings on mild steel in natural seawater was analyzed using Scanning Electrochemical Microscopy SECM and Electrochemical Impedance Spectroscopy EIS Line profile and topographic image analysis were measured by applying V and V as the tip potential for the cathodic and anodic reactions respectively The tip current at V for the epoxy coated sample with TiO nanoparticles decreased rapidly due to cathodic reduction of dissolved oxygen The EIS measurements were conducted in natural seawater after wet and dry cyclic corrosion test The EIS measured the film resistance Rf and charge transfer resistance Rct values which were increased by the addition of TiO nanoparticles in the epoxy coating SEM EDX and FIB TEM analysis showed that complex oxides of titania were enriched in corrosion products at the scratched area of the coated steel and confirmed the presence of the nanoscale oxide layers of titania in the rust of the steel The formation of complex oxides of titania had a beneficial effect on the corrosion resistance of coated steel