Topological transition in pressure-assisted sintering of amorphous powders

Abstract Powders consisting of particles with amorphous molecular structure spontaneously agglomerate by particle-particle sintering, altering their flow properties and perceived quality. Sintering is also employed to deliberately form agglomerated powder structures across different industries. Here, we investigate the effect of moderate uniaxial compaction pressure on the sintering kinetics of such powders. Combining experiments and discrete element modeling, we reveal a topological transition between two distinct sintering regimes. In the low-pressure regime, surface tension dominates, leaving the extent of particle connectivity unaffected by pressure. In the high-pressure regime, the topology of the connectivity changes, driven by the spatial distribution of contact forces. We propose a dimensionless “Rumpf number” to describe the ratio between surface tension and pressure effects, thereby identifying the transition threshold. These insights into pressure-assisted sintering offer quantitative guidelines for optimizing powder processing.