Effect of Interparticle Potential on Forming Solid, Spherical Agglomerates during Drying

The effect of the interparticle potential on the shapes of the agglomerates obtained by drying slurry droplets has been investigated using aqueous alumina slurries formulated in the dispersed and weakly attractive (dispersed + added salt) states. For the dispersed slurry, the droplets dried to irregular shapes with hollow centers. When just the right amount of salt was added to produce an attractive, but nontouching, particle network, the droplets dried as solid spheres. These results are discussed by relating both the nature of the particle network (repulsive or weakly attractive), the slurry rheology, and the consolidation mechanics of the networks to the requirements for maintaining a spherical geometry and uniform density during droplet drying.