Investigation of the influence of different organics combination on processing properties of spray dried ceramic granules

To optimize the processing properties of ceramic spray dried granules for die pressing applications the use of defined kinds and combinations of chemical additives is necessary. Within this paper the effect of binder PVA, dispersant NaPA and plasticizer PEG (pure and in combinations) on resulting suspension properties as well as on mechanical and processing properties of alumina oxide granules is studied. All granules were spray dried at two different solid content levels of the suspensions (40 wt% and 68 wt%) to investigate the influence of the solid content additionally. Even though there was no effect of any additive addition on suspension properties (pH value, solid content, viscosity) at the 40 wt% level, differences concerning viscosity could be measured at 68 wt% level. Varied mechanical granule properties like size distribution, flowability, bulk and tap density as well as single granule strengths were measured depending on the added organics and solid content. The addition of PVA leads to higher granule fracture loads, whereas PEG softens the granules. The addition of a dispersant to the binder PVA leads to a wider fracture load distribution. The addition of dispersant to the plasticizer PEG shows a strength increasing effect.