(101d) DEM Simulation and Analysis of the Effects of Compression Pressure on Appropriate Adhesive Force of Admixed Particle for Improving Packing Fraction

One technique for improving particle flowability is admixing smaller particles than original material particles (main particles). However, the mechanisms by which this technique improves flowability are not yet fully understood. In this study we examined compressed packing in a particle bed, which is affected by particle flowability. In order to estimate the mechanism of improvement, we investigated the effects of the compression pressure on appropriate adhesive force of admixed particle by DEM simulation.

The diameters of main and admixed particles were 400 and 20 nm, respectively. The physical properties of the particles were set based on silica and glass materials. The Hamaker constant of the main particles was kept constant while that of the admixed particle was changed from 2×10^-27 to 1×10^-20 J. The compression pressure was changed from 0.44 Pa to 176 Pa. From the bed height after a compression, we calculated packing fractions of main particle. As a result, the adhesive force of admixed particle at which shows the most improvement packing fraction decreased with decresing compression pressure. This result suggests that the appropriate adhesive force of admixed particles was determined by the the applied compressive pressure. In addition, this result was explained by magnitude relation between two forces. One is an adhesive force between admixed particles. The other is a shear force which acts on main particles.