Phase Transition Activity Characteristics of Nanosized AlOOH in the Hydrothermal Synthesis of nanosized α-Al_2O_3

摘要

α-Al_2O_3 nanopowders were prepared by a novel synthesis process, using the nanosized α-Al_2O_3 obtained from pyrolyzing ammonium aluminum carbonate hydroxide as seeds and the self-dispersed nanosized AlOOH crystal powders as precursors. Based on their good self-dispersion in water, the α-Al_2O_3 seeds were dispersed evenly into the AlOOH sol by the new homodispersion mixing technique. This process enables the conversion of AlOOH to alumina at 190℃ (hydrothermal temperature), in which the alumina is calcined to nanosized alpha-alumina having an average length to diameter ratio of 60nm:15nm at 930℃. In the synthesis reaction for transforming the AlOOH to alumina, the effect of superfine pulverization and self-dispersion of the precursors was studied.