Inter-particle spacing in aqueous suspensions of nanopowders and its effects on particle packing, green body formation and fabrication of alumina

Abstract

Despite the flexibility offered by a slurry-based processing of ceramics, fabrication of high-density products from nanopowders via conventional techniques is a challenge. The rheological behavior of nanopowder suspensions and the sintering processes of nanopowders have been thoroughly studied in the literature; however, the link between has commonly been overlooked. In this study, the packing behavior of alumina nanopowders and its relation to the rheological behavior of suspensions and the final sintered densities were investigated. For this reason, the availability of inter-particle spacing in aqueous nanopowder suspensions (IPSaq) was discussed. Funk-Dinger's relation was modified by means of electric double layer and hydration layer formed around oxide powders in aqueous media. The effects of IPSaq on the green body formation and alumina fabrication were explored in terms of densities and packing behavior. It was concluded that low viscosities or high green body densities do not necessarily lead to high-density end products. Yet, the availability of interparticle spacing in liquid media is vital to obtain efficient packing and high density in sintered products.