Colloidal processing of zirconia nanoparticles and production of sintered nanostructured ceramics

摘要

An important challenge in nanotechnology is the production of fully dense ceramic bodies of 100 run grain size microstructure from nanopowders available commercially. The aim of this work was to investigate the feasibility of producing nanostructured ceramics from commercial Zirconia nanopowders by a relatively simple low pressure casting. The Procedure entailed optimizing the process conditions for dispersion of suspension, consolidation into a green body and sintering. The widely employed transmission electron microscopy (TEM) technique for measuring the size of nanoparticles proved quite inadequate for processing of nanoparticles in ceramic fabrication, whereas laser light scattering technique provided more reliable estimates of the degree of dispersion. It was possible to prepare green bodies having relatively fine and uniform size pores from well dispersed nanodispersions when consolidated in an appropriate manner. The green compacts were sintered to nanostructured and fully dense products at significantly lower temperatures. For example, a well dispersed nanozirconia of 62 nm mean size was fabricated into a fully dense sintered compact having a grain size of less than 100 nanometers at a firing temperature of 1300_C only. On the other hand, the as received so-called nanozirconia powder, which included aggregates, could not be sintered to full density even at much higher temperatures. The work presented here highlights, perhaps more than the consolidation techniques, the importance of dispersion science in the production of nanostructured ceramics.