PROCESS FOR OBTAINING ALPHA-ALUMINA POWDERS WITH SUBMICRON MEDIAN PARTICLE SIZE

摘要

A process for obtaining alpha-alumina in powder form having a particle median size distribution D50 from 0.1 to 1 micron and having coarse particles larger than 3 microns being less than 2% comprises subjecting solid powder of hydrated Al2O3, or hydrated aluminium chloride or sulphate, to a calcination treatment to transform it to alpha-phase alumina and to obtain a powder having a surface area from 2 to 12 m<2>/g; and grinding the powder.