Density difference in pressure‐filtrated wet cakes produced from spontaneous gelling slurries.

Pressure filtration is a key process in ceramic forming; however, the influences of density difference in different parts of a pressure‐filtrated wet cake on subsequent drying and sintering have not yet been explored. In the present work, alumina slurries dispersed by copolymers of isobutylene and maleic anhydride (PIBM) and ammonium salt of polyacrylic acid (PAANH4) were pressure filtrated to examine the impacts of density difference in the as‐prepared wet cakes. In comparison to the wet cake produced from PAANH4, the wet cake with PIBM had much higher bulk density and smaller density difference between its upper and bottom parts (height of ~23 mm). Furthermore, in order to reveal the differences between these two wet cakes, the nature of agglomerates in their slurries was investigated. The slurry with PIBM contained agglomerates with a wider size distribution, bigger average size, and higher sphericity, producing a wet cake with a higher particle packing density and more homogeneous packing structure after pressure filtration. Hence, almost no deformation occurred in a large wet cake (280 mm × 130 mm × 20 mm) with PIBM, whereas that with PAANH4 experienced a severe deformation after sintering. [ABSTRACT FROM AUTHOR]