Original paper(Vol.47 No.4 pp.388)

Binding property of r-alumina fora-alumina slurry
- Effect of specific surface area of r-alumina on hardening of slurry -

Ishikuro Tomoaki; Suzumura Akio; Ogawa Hirotaka

Abstract:The effect of the specific surface area of added r-alumina on hardening of a-alumina slurry was investigated by the measurement of the penetration resistance of a-alumina slurry. r-alumina was made by the heating of Al(OH)3 from 200 to 700 degree in vacuum. The penetration resistance increased with increasing holding time. The holding time required to reach the same penetration resistance decreased with increasing specific surface area of r-alumina, when it contained neither Al(OH)3 nor h-alumina. In the case where Al(OH)3 remained in r-alumina (heat treated below 300 degree C), the hardening of the slurry proceeded more rapidly than that of the slurry without Al(OH)3, exhibiting about the same specific surface area. When h-alumina was formed (heat treated above 600 degree, then the hardening of the slurry proceeded more slowly than that of the slurry without h-alumina.

Key Words:r-alumina, specific surface area, penetration resistance, hardening time