Preparation of ultrafine α-Al_2O_3 powder by homogenous precipitation

Al(OH)3 was synthesized as the precursor by the precipitation reaction of aluminum sulfate and urea,which was calcined to get ultrafine α-Al2O3.The effects of mole ratio of CO(NH2)2 to Al2(SO4)3,initial concentrations of Al2(SO4)3,reaction temperature and reaction time on the preparation of α-Al2O3 were investigated.The structural properties of powder were characterized by X-ray diffractrometry,scanning electron microscope and DTA/TGA measurements.The results show that spherical ultrafine α-Al2O3 powder with non-aggregation and the average particle size of about 2 μm was produced under the conditions: mole ratio of CO(NH2)2 to Al2(SO4)3 is 10?1,initial concentration of Al2(SO4)3 is 0.05 mol/L,reaction temperature is 90 ℃ and the reaction time is 6 0 min.