Experimental study on the time change in fluidity and particle dispersion state of alumina slurries with and without sintering aid

The time change of the fluidity and particle dispersion state of alumina slurries with and without a sintering aid were investigated. The apparent viscosity of the slurry was measured at certain intervals. The hydrostatic pressure of the slurry, which represents the particle dispersion state, was also measured. We showed that the pH value, adsorbed amount of dispersant, and Mg ion concentration of the slurry hardly changed with time even though the apparent viscosity of the slurry increased with time. We suggest that the time change in the apparent viscosity, that is, the behaviour in which the apparent viscosity of the slurry increased with time, occurs when the electrostatic repulsion force is insufficient to maintain the particle dispersion state for a long time, such as shortage in the dispersant to its saturated amount.