COLLOIDAL PROCESSING OF SUBMICRON ALUMINA POWDER COMPACTS

This study investigates the compaction and sintering characteristics o f narrow-size-distributed sub-micron alumina powder compacts. Near-mon o-sized powder with a mean particle size of 0.18 mu m was processed co lloidally and then compacted by either centrifuging or slip casting. G reen densities comparable to that of dense random compacts of equal-si zed spheres were obtained over the range of suspension concentrations and compacting conditions explored. The resultant compacts had a unifo rm green microstructure and exhibited improved sintering characteristi cs, as opposed to those prepared by dry pressing. Full densification w as achieved in 1 h at 1275 degrees C, yielding a final grain size of a bout 0.5 mu M. The effects of the initial particle size and the size d istribution on the compacting and sintering characteristics of colloid ally processed sub-micron alumina compacts are also presented and disc ussed. (C) 1997 Elsevier Science S.A.