ALPHA-ALUMINA POWDER AND PROCESS FOR ITS PRODUCTION.

摘要

A process for producing alpha -alumina powder comprises calcining transition alumina and/or a transition alumina precursor which transforms to transition alumina on heating, in a gas atmosphere containing (1) a hydrogen halide, (2) a component prepared from a halogen and steam or (3) a halogen, and in the presence of seed crystals and/or a shape-controlling agent. The product alpha -alumina powder comprises particles of a substantially octahedral or eicosa-hedral shape, a pre-determined structure, and a narrow primary particle size distribution; the powder is particularly useful as a raw material for preparing abrasives, fillers, sinters or spacers.