Processing of zirconia nanoceramics from a coarse powder

We have merged the benefits of coarse-grained and nanocrystalline powders by the consolidation and sintering of coarse, yet nanostructured, mesoporous Y-TZP powder. The powder was composed of loosely aggregated, nanoscale crystallites, which can be seen as secondary particles or agglomerates. Their homogeneous, defect-free packing proved to be a viable pathway for the processing of zirconia nanoceramics. The powder consolidation yielded homogeneous green bodies with hierarchical heterogeneities in terms of intra- and inter-particle pore packing. The hierarchical heterogeneities had a pronounced effect on the densification and grain growth. The intra-particle pore coalescence along with a “frozen” inter-particle porosity, prolonged the pore-pinning effect, separating the densification and grain-growth mechanisms. Increased heating rates promoted the grain growth and densification via a competitive mechanism of primary crystallite ordered coalescence, while by applying pressure, the crystallite growth was completely prevented, making such a coarse powder suitable for the fabrication of zirconia nanoceramics.