Effect of Main Particle Diameter on Improving Particle Cohesiveness in a Fine Particle Admixing System

Abstract

One of the techniques used to improve particle cohesiveness is the admixing of nano-particle to main particles. However, the mechanism for this improvement in cohesiveness has not been clarified yet. In the present study, we focused on compressed packing as one of the operations that is affected by particle cohesiveness, and we investigated the effects of the main particle diameter on the improvement in the cohesiveness. The main and admixed particles were 397, 1566 nm and 8, 21, 62, 104 nm in diameter, respectively. The main and admixed particles were mixed for various mass ratios, and compressed packing fractions for the mixed particles were measured. SEM images were used to analyze the coverage diameter and the surface coverage ratio of the admixed particles on the main particles. As a result, the improvement in the cohesiveness was obtained easily when the diameter ratio (=main particle/ admixed particle) increased. This was explained by the linking rigid-3-bodies model applying the principle of leverage. Furthermore, the surface coverage ratio showing the most improvement increased with main particle diameter. This was explained by the contact probability of the main particles based on the curvatures in the main particle surface.