Characterization of slurries for slip casting via constant pressure filtration: determination of the most suitable slurry property for controlling the green-body density

In slip casting, predicting the packing fraction of the slip-cast green body based on slurry characteristics is important. Thus, in this study, we measured the apparent viscosity and packing fractions of the sediment and filtered cake of aqueous alumina slurries containing dispersants and binders. In addition, the slurry was slip-cast and we measured the packing fractions of the slip-cast green body. It was demonstrated that the correlation efficient between the packing fractions of the filtered cake and the green body was extremely high, more than 0.968, while the correlation coefficients between the apparent viscosity or the sediment packing fraction, and the packing fraction of green body were 0.203–0.758. We found that the change in the particle dispersion state during constant-pressure filtration and slip casting owing to the dispersant expelled from the slurry affected the packing fractions of the filtered cake and slip-cast green body. We conclude that the packing fraction of the filtered cake is the most reliable index among all slurry properties measured in this study for predicting the packing fraction of the slip-cast green body. Constant pressure filtration of the slurry is therefore expected to be an effective method for optimizing slurry conditions in slip casting.