Characterization of nano-particle dispersion in a silica slurry

TEM observation of an in situ solidified slurry was used to characterize the dispersion and structure of nano-particle silica in a slurry. Direct observations were made by TEM to visualize the stereoscopic structure of the silica nano-particle structure in a slurry. These observations were then compared with the measured zeta potential and slurry viscosity. Flocculation is observed at pH 1-2, where the zeta potential is low, and the viscosity is high. The nano-particles form a three-dimensional network at pH 6.35, and the network structure disappears at pH 7.02. The silica nano-particles re-agglomerate at pH 8.43-10.43. Particle dispersion/aggregation changes significantly with pH although slurry viscosity is relatively constant in the range of pH 6-10. By comparing TEM observations to zeta-potential and viscosity measurements, we verified that that the observed structure reflects the actual structure in the slurry.