Rheology of Nanometric Powders

Use of environmentally friendly processing additives for nanometric powders has tremendous technological implications. In this study, the rheology of aqueous nanometric alumina powdersuspensions and variation of viscosity with solids content and with fructose concentration were studied by rheometry. The mechanism of dramatic viscosity reduction by fructose addition is studied by differential scanning calorimetry (DSC) and thermogravimetry (TGA). The interparticle forces between the particles were investigated by colloidal probe-atomic force microscopy (CP-AFM). DSC indicates that the significant fraction of water is bound on the surface hence does not contribute to flow of the particles. It also indicates that the fructose displaces water from the particle surface and reducing the interparticle forces. The interactions between the nanometric alumina particles in water can be explained by the DLVO theory. The interaction forces (amplitude and range) between nanometric alumina particles decrease with increasing fructose concentration.