Preparation of Fineα-Al_2O_3 Powders by Calcining Carbon-coveredγ-Al_2O_3 in Oxygen

A new method for the preparation of fineα-Al_2O_3 powders was reported.C/γ-Al_2O_3 composites were prepared by carbonizing starch/γ-Al_2O_3 precursors.Calcining the composites under oxygen flow in a furnace at 800℃,rapid and total transformation ofγ-Al_2O_3 toα-Al_2O_3 occurred when the carbon content was between 6wt%-13wt%.Characterized by N_2 adsorption technique and SEM observation,the particle size of the as-prepared a-Al_2O_3 powders is about 2μm.By this method,γ-Al_2O_3 can be transformed in very short time of about several minutes toα-Al_2O_3 at 800℃,which is much lower than the temperature for the commercial preparation.The method is very efficient for the rapid preparation of fineα-Al_2O_3 powders.And the simple operation and cheap raw materials for the method show that it is very promising for industrial applications.