| Wet ground and washed Bayers alumina of micron and submicron
order formed agglomerates when the powder was calcined at sufficiently
high temperatures. The agglomerates became increasingly
stronger with increasing temperature of calcination. Grinding, leaching
with acid and finally washing with distilled water caused surface
hydration which was evidenced by loss in weight on ignition and
pycnometric density of alumina powders calcined at different temperatures.
Pore volume reduction of agglomerates thus formed at
temperatures above 1100°C caused remarkable improvement in the
packing density of alumina bodies using the calcined powders. However,
in order that a good alumina body may be formulated, the use
of fused alumina grains seemed to be unavoidable. |
