Production of grinding balls from submicron powders

Impact load level, defect anal., and manufg. sequence of grinding balls of alumina for high-purity nanodispersed powder milling are studied. For this the grinding ball material compn. should be identical with the raw material compn. to be milled. Common compaction, sintering, and final hot isostatic pressing of balls prepd. from fine dispersed (< 300 nm) powders do not lead to the required green body densities and low defective microstructure. With help of fluidized solids technique the manufg. of homogeneous, fine grained, and dense green body spheroids can be performed requiring also low sintering temps.