Microstructure-based discrete simulations of the compaction of refractory powder composites

This work describes an original methodology to simulate the compaction behavior of refractories by taking explicitly into account the microstructure of each composite phase. The Discrete Element Method (DEM) is used to model the composite as a mixture of fine and coarse alumina particles and graphite flakes. The binder phase is accounted for by a specific contact law which adjusts the contact rigidity according to the indentation between the coated particles. Small indentations lead to a soft response while above a critical indentation, the contact becomes stiffer. This simple model incorporates the granular behavior of the composite as well as the continuous matrix of the binder. Composites with various compositions are numerically submitted to closed-die compaction. The densification behavior during compaction depends primarily on the binder phase. The contribution of each phase to the total axial stress is investigated, thus providing new insights into the complex behavior of these composites.