Application of EIS and SECM Studies for Investigation of Anticorrosion Properties of Epoxy Coatings containing ZrO2 Nanoparticles on Mild Steel in 3.5% NaCl Solution
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The effect of corrosion protection performance of epoxy coatings containing zirconium oxide (ZrO2) nanoparticles on carbon steel was analyzed using scanning electrochemical microscopy (SECM) and electrochemical impedance spectroscopy (EIS). Localized measurements such as oxygen consumption and iron dissolution were observed using SECM in 3.5% NaCl in the epoxy coated sample. Line profile and topographic image analysis were measured by applying −0.70 and +0.60 V as the tip potential for the cathodic and anodic reactions, respectively. The tip current at −0.70 V for the epoxy coated sample with ZrO2 nanoparticles decreased rapidly, which is due to cathodic reduction of dissolved oxygen. The EIS measurements were conducted in 3.5% NaCl after wet and dry cyclic corrosion test. The film resistance (R f) and charge transfer resistance (R ct) values were increased by the addition of ZrO2 nanoparticles in the epoxy coating. SEM/EDX analysis showed that oxides of Zr were enriched in corrosion products at a scratched area of the coated steel after corrosion testing. Focused ion beam-transmission electron microscope analysis confirmed the presence of the nanoscale oxide layers of Zr in the rust of the steel, which had a beneficial effect on the corrosion resistance of coated steel by forming protective corrosion products in the wet/dry cyclic test.
KeywordsCorrosion Epoxy coating ZrO2 Nanoparticle EIS SECM
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