Generation of γ-Al₂O₃ Microparticles by Hybrid Electrochemical-Thermal Method and its Zn-γ-Al₂O₃ Composite Coating for Corrosion Protection

Microcrystalline alumina (γ-Al₂O₃) powder was successfully synthesized by hybrid electrochemical-thermal method. The as-synthesized powder was calcined for an hour at temperatures ranging from 60°C to 900°C. The crystallite size, morphology, and chemical state of the synthesized powders were characterized by powder XRD, TG-DTA, XPS, SEM/EDAX, TEM and FT-IR spectral methods. The effect of calcination temperature on crystallite size and morphology was assessed. Scanning electron photomicrographs show a cauliflower like morphology and EDAX measurement showed its chemical composition. Thermal behavior of as-synthesized product was examined. The TEM result revealed that, the particles are cauliflower in nature with diameter of 0.2–0.5 μm. The crystallite size increased with increase of calcination temperature. The electrochemically generated γ-Al₂O₃ powder was used to fabricate Zn-γ-Al₂O₃ composite thin films and its corrosion behavior was analyzed by anodic polarization, tafel extrapolation and electrochemical impedance spectroscopy. The results indicate that the Zn-γ-Al₂O₃ composite thin films have potential applications to corrosion protection.