Influence of Solid Loading on the Granulation of 3Y-TZP Powder by Two-Fluid Spray Drying

The influence of solid loading in the slurry composition on the morphology of 3Y-TZP granules fabricated by two-fluid spray drying was investigated for solid contents varying between 30 wt% and 50 wt%. The resulting 3Y-TZP granules showed a sphere-like shape with diameters of 40 - 70 μm. However, a donut-like shape and a few cracks were observed on the granule surfaces fabricated using the slurry with 50 wt% solid content. The green density after cold isostatic pressing at 200 MPa was 2.1 - 2.2 g/cm3, and a homogeneous fracture surface was obtained by complete destruction of granules. After sintering at 1500°C for 2 h, all specimens had relative densities of 96.2 - 98.3%. With increasing solid content, the relative density decreased from 98.3% to 96.2%, but the grain size increased from 0.3 μm to 0.6 μm. Highly sinterable zirconia granule powder could be obtained by controlling the slurry composition. Key words: Zirconia, Granule morphology, Spray drying, Sintered density