Al2O3 Microspheres Prepared by Cathode Plasma Electrolysis

Al2O3 microspheres were prepared by cathode plasma electrolysis (CPE) in an aqueous solution of Al(NO)3·9H2O. Compared with high-temperature calcination methods, the CPE method afforded the preparation of microspheres directly at room temperature. The results showed that regular microspheres formed under relatively high concentrations of Al(NO)3·9H2O. The microspheres, with diameters mostly in the range of 5–30 μm, consisted of γ-Al2O3 and α-Al2O3. The possible formation mechanism included the following processes: (1) Al(OH)3 intermediate was formed during the cathodic reactions; (2) plasma energized the intermediate to Al2O3; and (3) microspheres formed under the effect of the surface tension.