Modeling the uniaxial compaction of pharmaceutical powders using the mechanical properties of single crystals. I: Ductile materials.

A model is presented which uses the Vickers microindentation hardness of ductile crystals such as sodium chloride to predict the uniaxial compaction behavior of compacts. A general approach first developed in the materials science field to predict the densification of particulate matter under hydrostatic loading was followed. However, modifications to account for the effects of particle geometry and the closed-die loading conditions were considered. Using the standard microindentation hardness value of sodium chloride, the model predicted the densification behavior of this material at a punch displacement rate of 1 mm/min. Densification at higher compaction rates was predicted by considering the effect of deformation kinetics on the hardness. Secondary factors which affect compaction, such as particle size effects and die-wall friction, are also briefly discussed.