Sintering of Fine Oxide Powders: II, Sintering Mechanisms

Conventional and new sintering mechanisms have been porous compacts is well-known in the ceramic literature. However, several reports have been presented recently that investigated using fine powders of CeO2 and Y2O3 of excellent sinterability. We have verified the validity of Herring’s show that particle/grain size can remain essentially constant up to a density of 92%, and such a resistance to coarsening has scaling law for 60%–84% relative density and found that it is consistent with grain-boundary-diffusion control. At been claimed to be essential for good sinterability because it signifies uniform packing. These observations also have lower densities, we have found that pores larger than the critical size, in the sense of Kingery and Francois, can still reinforced the notion that sinterability reflects the competition between densification and coarsening and that coarsening is be sintered readily. This is rationalized by a new sintering mechanism based on particle repacking concurrent with detrimental to good sinterability. However, in our study of fine CeO2 and Y2O3 powders, we have found good sinterability, particle coarsening, resulting in a higher packing factor. Very fine, surface-active powders that coarsen rapidly are regardless of coarsening behavior. Specifically, CeO2 coarsened more than Y2O3 at comparable temperatures and densities; uniquely capable of taking advantage of this new sintering mechanism, which along with their propensity to homogeniyet, compacts of both oxides could be readily sintered to full density. Coarsening was further found to begin at very early zation, accounts for their remarkable sinterability even at stages, in all cases 92%. These observations with fine powvery low green densities. ders clearly contradict the popular notion of an inverse correlation between sinterability and coarsening. Because this strong