Influence of Mechanical Activation of Al_2O_3 on Synthesis of Magnesium Aluminate Spinel

摘要

Magnesium aluminate (MA) spinel is synthesized by reaction sintering from alumina and magnesia. The effects of mechanical activation of Al_2O_3 on reaction sintering were investigated. Non-milled a -Al_2O_3 and a - Al_2O_3 high-energy ball milled for 12h, 24h and 36h were mixed with a MgO analytical reagent according to the stoichionietrie MA ratio, respectively and pressed into billets with diameters of 20mm and height of 15 mm. The green-body billets were then sintered at high temperature in an air atmosphere. The results show that bulk density, relative content of MA. and grain size of MA increase with increasing high-energy kail milling time of Al_2O_3. However prolonged milling time over 24h has a small beneficial effect on the densification of MA. Bulk density and grain size of a sample of a-Al_2O_3 milled for 24h are 3,30g/cm~3 and 4-5 mu m, respectively.