Theoretical analysis of electrostatic forces between coated particles

Electrostatic forces between coated particles have been theoretically analyzed taking into account the polarization arising from the contact potential difference around the interface between the core and the coat. A simple model for a pair of dipoles is presented to clarify the fundamental electrostatic forces. Furthermore, three-dimensional arrangements of many dipoles are considered. The electrostatic forces, which depend on the arrangement of the dipoles, can be positive (repulsive) as well as negative (attractive). However, the repulsive forces can be much larger than the attractive ones. This implies that control of the polarization in coated particles leads to an improvement in the flowability and dispersibility of powder particles.