Surface area reduction during the sintering of alumina

Surface area reduction trajectories of two well characterized calcined alumina powders were analyzed over a range of thermal profiles. Surface area reduction trajectories were confirmed to be independent of initial green density. Variations in trajectory were explained through experimental demonstrations of blended coarse and fine particle alumina systems. This work demonstrates that (1) nanoparticles do not appear to assist conventional sintering, because the nanoparticle surface area drops precipitously with minimal increase in density; and (2) the initial compact density does not contribute, nor control, surface area reduction during alumina sintering.