The Evaluation of the Dispersion Behavior of Aqueous Silicon Nitride Suspensions by the Aggregation Rate Method

The dispersion behavior of aqueous silicon nitride suspensions in the presence of polyacrylic ammonium as a dispersant was characterized using a method, which is based on the measurement of the aggregation rate. The stability factor which indicates the resistance of suspension to aggregate increased with increase in the amount of added dispersant, but it reached a limiting value in the high concentration range of the dispersant. The minimum amount of added dispersant to achieve sufficient stability was about 1mg/g-solid at pH 8-9 of a highly concentrated slurry. Both the minimum amounts obtained by the measurement of the volume of sedimentation and the apparent viscosity of a slurry agreed well. This confirmed the feasibility of using the aggregation rate method.