PREPARATION OF ACICULAR PARTICLES OF ALPHA-ALUMINA

Aluminum ammonium sulfate (AA) solution (0.1 mol/l) and ammonium hydro gen carbonate (AHC) solution (1.2 mol/l) were allowed to react at room temperature. The precipitates formed were kept with the mother liquor in a closed vessel and aged at 100 degrees C, Acicular-shaped crystal line particles of Al(NH4)CO3(OH)(2), (AACH), were obtained after the e longated aging period. Acicular alpha-alumina particles were obtained through the thermal decomposition at 1300 degrees C out of the AACH pa rticles which were previously treated with a small amount of tetraetho xysilane (about 1.6 wt. % of SiO2).