Colloidal processing of sub-micron alumina powder compacts

Abstract

This study investigates the compaction and sintering characteristics of narrow-size-distributed sub-micron alumina powder compacts. Near-mono-sized powder with a mean particle size of 0.18 μm was processed colloidally and then compacted by either centrifuging or slip casting. Green densities comparable to that of dense random compacts of equal-sized spheres were obtained over the range of suspension concentrations and compacting conditions explored. The resultant compacts had a uniform green microstructure and exhibited improved sintering characteristics, as opposed to those prepared by dry pressing. Full densification was achieved in 1 h at 1275°C, yielding a final grain size of about 0.5 μm. The effects of the initial particle size and the size distribution on the compacting and sintering characteristics of colloidally processed sub-micron alumina compacts are also presented and discussed. © 1997 Elsevier Science S.A.