Effects of coating structures prepared under various mixing strength conditions for main and smaller admixed particles on improving compacted packing fraction

Abstract

Particle flowability can be improved by admixing with particles smaller than the original main particles. However, the effects of the admixed particle coating structure for the main particle surface on the improvement of flowability are not fully understood. In this study, we investigated the effects of coating structures prepared under various mixing strength conditions (compression force and rotational speed) on particle compaction flowability. The main and admixed particles for various mass ratios were mixed in various mixing strength conditions and the compacted packing fractions of the mixed particles were measured. SEM images and SAXS were used to analyze the surface coating ratio, coating diameter, and fractal dimension of the admixed particles on the main particle surfaces. The difference in fractal dimension calculated from the SAXS data and the coating diameter ranges of the admixed particle agglomerates obtained from SEM images showed that the improvement mainly depended on coating structures in agglomerates 30–60 nm in size of the admixed particles. An optimal coating structure for improving the compaction flowability was an average gap between agglomerates on the main particle surfaces of around 2–3 times the coating diameter. This result was explained by a linked rigid three-body model movement.