Corrosion Characteristics of Zn-TiO2 Nanocomposite Coatings Fabricated by Electro-Codeposition Process abstract
Zn based composite coatings reinforced with
TiO2 nanoparticles were fabricated via electrodeposition with 5, 10, and 15 g/L
TiO2 concentration under variant current densities of 0.08, 0.1 and 0.12 A/cm2. Field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), x-ray diffraction analysis (XRD), weight loss measurements, salt spray technique, anodic polarization, and eventually potentiodynamic polarization tests were conducted and the corresponding findings were discussed. Rising the electrodeposition current density from 0.08 to 0.12 A/cm2 for both pure Zn and Zn-TiO2 coatings led to deposit more and smaller crystals and with incorporation of
TiO2 nanoparticles, the
morphology changed from hexagonal crystals to flake type grains. Increasing the
TiO2 concentration from 5 to 15 g/L, steadily lowered the
TiO2 incorporate rate (vol.%). Accordingly, the same smoothness and even more uniformity with smaller crystallites was observed at 15 g/L compared to that of 5 g/L. Weight loss measurements, salt spray tests and anodic polarization test showed remarkable superior corrosion resistance of Zn-TiO2 (5 g/L) than that of pure Zn coating. An increas in icorr (µA/cm2) from 0.08 to 0.1 A/cm2 occurred, followed by a decrease from 0.1 to 0.12 A/cm2 for pure
zinc coating. By increasing the current density from 0.08 to 0.12 A/cm2 for Zn-TiO2 coating, a steadily decrease of icorr was observed. Furthermore, by rise of
TiO2 (%C) from 5 to 15 g/L, icorr experienced a significance increase that could be ascribed to the remarkable reduction in
TiO2 vol.%. Ultimately, the optimum corrosion resistance belonged to the electrodeposited Zn-TiO2 (5 g/L) coating deposited 0.12 A/cm2 exhibiting the lowest amount of icorr of 2.7 µA/cm2 equal to 1.6 mpy.