Effect of nanopowder deagglomeration on the densities of nanocrystalline ceramic green bodies and their sintering behaviour

摘要

The agglomeration of nanoscaled powders ingeneral in general decreases the density if green bodiespressed from those nanopowders. Depending on the strengthand morphology of the agglomerates different densitiescan be achieved. It is shown that in the case of ceramicnanopowders as alumina and yttria-stabilised zirconiawhich are produced by laser ablation technique or in thecase of alumina also by physical vapour synthesis processthe stronger agglomerates can easily be cracked by a shortmilling procedure. Green bodies pressed from theconditioned nanopowders exhibit up to 15% largerdensities than bodies made from unmodified nanopowders.Due to the decreased porosity in those specimens thesintering activity is significantly increased andtherefore ceramics of up to 99% of the theoretical densityhaving median grain diameters less than 500 nm can bemanufactured under simplified processing conditions.