Abstract: α-Al2O3 was prepared by the sintering method with industrial alumina as raw material and 5% AlF3+ 0.5%-2% H3BO3 , 5% H3BO3+ 0.2%-1.4% AlF3 and 1% AlF3+ 1% - 4% NH4Cl as compound mineralizers, respectively. The effects of different mineralizers on the structure and composition of α-Al2O3 powders were analyzed by laser particle sizer, X-ray diffraction(XRD) and scanning electron microscopy (SEM). The results show that the optimized compound mineralizers could reduce the impurities in α-Al2O3 powders. The content of Na2O in α-Al2O3 powders decreases as the amount of AlF3 and H3BO3 increases. When the amount of AlF3 and H3BO3 are 5% (mass fraction) and 2% (mass fraction), the Na2O content is 0.04% (mass fraction). In addition, the introduction of AlF3 and NH4Cl can change the morphology of α-Al2O3 into flakes, and H3BO3 can change the morphology of α-Al2O3 into spheres.
Key words: α-Al2O3 ; mineralizer; structure; composition; sintering