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

• Published in: Journal of the American Ceramic Society 2012-07, Vol.95 (7), p.2298-2306
• Main Authors: Chandrappa, Kodihalli G., Venkatesha, Thimmappa V.
• Format: Article
• Language: English
• Subjects: Calcination; Cauliflowers; Corrosion prevention; Crystallites; Morphology; Protective coatings; Transmission electron microscopy; Zinc
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/j.1551-2916.2012.05248.x

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.