Powders containing particles of sub-micron size are normally agglomerated, and the size and strength of the agglomerates depend on the chemical nature of the material and its surface chemistry, primary particle size and shape and their distributions, and the atmospheric environment. The dispersion of such agglomerates in liquid media involves their breakdown into primary particles and the replacement of solid/gas by solid/liquid interfaces. Maintaining a high degree of dispersion requires that flocculation of dispersed primary particles must be prevented. Sometimes flocculation is desirable, and various types of flocculated structures are possible which differ in strength.
This project aims at understanding the forces that determine powder agglomerate strength and their relation to the energy required for dispersion in liquid media in terms of both chemical (wetting) and mechanical (milling) effects, Once these are understood and the conditions for effective dispersion are established, flocculation will be induced and the strength of floes measured.