| 摘要 |
PURPOSE:To produce spherical alumina by successively subjecting Al(OH)3 obtd. by the Bayer process to heating, hydration and thermal decomposition, further heating and interim firing, refiring the resulting Al2O3 in the presence of a specified amt. of a fluorinating agent and controlling the particle diameter. CONSTITUTION:Al(OH)3 obtd. by the Bayer process is successively subjected to heating at <=20 deg.C/min heating rate, dehydration and thermal decomposition at <=700 deg.C, further heating and interim firing at <=1,400 deg.C to form Al2O3 having <=0.5wt.% total sodium content and <=90% alpha-Al2O3 content. A fluorinating agent such as AlF3 is added to the Al2O3 by 0.05-1.0 pt.wt. (expressed in terms of F) per 100 pts.wt. of the Al2O3 and this Al2O3 is refired at 600-1,500 deg.C. The crystals are grown, the particle diameter is controlled and spherical Al23 having a low sodium content is obtd. |
