Designing slurry conditions to control size distribution of spray-dried dense YSZ granules

This study suggests approaches to achieve the desired size and size distribution of highly dense spherical granules by investigating the effect of slurry conditions on size distribution. Highly dense spherical granules were prepared with a solid content of over 77 wt% by spray-drying the slurry. A prolonged deagglomeration time of 64 h provided adequate flowing ability by breaking up almost all aggregates and improved dispersibility, resulting in reduced granule sizes and narrow size distributions. The optimum slurry conditions for maintaining dispersibility were 1 wt% of the dispersant and a strong basic pH, which had the greatest effect on size distribution. Based on these considerations, the 10.6 µm sized 3 mol% yttria-stabilized zirconia granules were synthesized with 99.83% density, 97.17% sphericity, and uniform size with fraction yield of 80.01% at 10–20 µm. These dense granules have significantly higher hardness and modulus values of 19.19 and 206.68 GPa, respectively, than that of pellet and film types. To the best of our knowledge, the relationship between the slurries and the span of the size distribution of ceramic granules during spray-drying has been demonstrated for the first time.