The effect of different milling methods applied in the production of Al2O3 ceramics

The effects of different milling methods applied during production of a
99,7 % alumina quality from a commercial Bayer alumina powder were
studied in an interlaboratory test. Grinding and doping of the powder
with MgO was carried out by stirred ball or vibration ball milling,
with different milling media and linings of the mills. The powder
batches were consolidated by pressing, sintering and post HIPing. The
materials were characterized in different stages of the production
process in order to analyze the role of contamination by wear debris
and of the granulometry on microstructure and mechanical properties of
the final products. It could be shown, that a satisfying agreement in
the results of different laboratories was achieved for common
characterization methods. The sensitivity of the applied methods turned
out to be sufficient to detect differences in contamination and
granulometry, which lead to significant variations in microstructure
and properties of the final products.