CENTRIFUGAL SLIP CASTING OF ZIRCONIA (TZP)

Tetragonal zirconia (3Y-TZP) ceramic parts were produced via centrifugal slip casting. This forming method combines the advantages of wet powder preparation with a very efficient densification technology to produce massive and near-net-shape ceramic parts. Aqueous TZP slurries with solids contents up to 42.3 vol.% and low viscosity were prepared using Darvan C as a deflocculant and ultrasonic cavitation to achieve a good homogenization. At solids loadings above 40 vol.% differential segregation effects during centrifugation are negligible. Very good particle packing with narrow pore size distributions (from r25=21.1 nm to r75=17.3 mm) were achieved. High green densities of up to 57% of theoretical density ( TD) were obtained after centrifuging at 4000 g for 90 min. High sintered densities (> 99.3% TD) were achieved at sintering temperatures as low as 1300-degrees-C with 2 h holding time. Sintered compacts have a very fine microstructure with an average grain size of 0.3 mum and narrow grain size distribution. Centrifugal slip casting has the potential to produce massive ceramic parts with reduced defect sizes and thus high reliability.