Internal cohesion of agglomerates: II. An elementary approach for assemblies of weakly agglomerated 3d-clusters

The fundamental feature of powder constituted of aggregated particles is their cusp structure, which is reproduced by the simpler geometry of fractal clusters generated on lattice. The average internal cohesion of three-dimensional (3d)-agglomerates formed by assemblage of clusters of mass i and j (the clusters being previously obtained using the algorithms of the diffusion- or reaction-limited aggregation processes) was determined by the set of the numbers P(v, i, j) of the interagglomerate links ensured by v connections. This number was obtained from inspection of all nonoverlapping configurations. The fate of the link during fragmentation was determined by setting the number m of connections, which may be broken. The mass of agglomerates sustaining fragmentation, which was found to be slightly dependent of the mass (i+j) of the final agglomerate was expressed by a Johnson–Mehl equation of the variable m. When additive (binder) is mixed with powder to induce grain agglomeration, the agglomeration model showed that only particles belonging to the external envelope of the aggregates become coated, and correlated the additive dose, aggregate characteristics (mass or mass frequency) and effective surface coating.