Green forming with nanoparticles

The potential for green forming with nanosized yttria-doped, partially stabilised zirconia (YPSZ) powder using both uniaxial compaction and colloidal suspensions has been investigated. Green compacts were fabricated from a Y-PSZ nanopowder, a submicron powder of similar composition and combinations of the two by die pressing at varying axial stress, with the effect of a micronising milling process on the green density also being examined. Results indicated that the incorporation of the nanopowder into the submicron powder increased green density by up to 17% whilst micronising helped to achieve green densities as high as 60% of theoretical, even with the pure nanopowder. The zeta potential, viscosity and mean particle size of two different Y-PSZ nanosuspensions were measured for two different anionic polyelectrolytes, polyacrylic acid (PAA) and polymethacrylic acid (PMAA). The results showed that both led to flocculation under acidic conditions and hence increasing viscosity with increasing polyelectrolyte concentration.