Three-dimensional granular dynamics simulations of polydisperse and bidisperse nanopowders compaction processes

Nanopowder uniform compaction processes are simulated by the three-dimensional granular dynamics method. The interaction of particles in addition to wide-known contact laws involves the dispersion forces of attraction and possibility of interparticle solid bridges formation, which have a large importance for nanopowders. Different model systems are investigated: monosize systems with particle diameter of 10, 20 and 30 nm; polydisperse systems corresponding to the log-normal particle size distribution law with different width; bidisperse systems with different content of small (the diameter is 10 nm) and large (30 nm) particles. The deviations of compact density in polydisperse systems from the density of corresponding monosize system are found to be minor. Non-monotone dependence of compact density on the weight fraction ωm of small particles is revealed in the bidisperse systems, where the density maximum is found to be about 7-8% in the vicinity of ωm = 0.35.