粒子特性と充てん性

抄録

As an approach to reviewing the packing properties of fine powders, the relationships between particle characteristics such as particle size, shape, surface roughness and adsorbed matter, and static properties of powders have been studied.
In this experiment, the white alundum, zinc powder, calcium carbonate and mica powder were used as samples. The angle of repose, porosity and packing property were measured as static property of powders.
The results obtained are summarized as follows:
As particle size decreases, the angle of repose and porosity increases. But the value becomes constant under the critical size of the particles at hard coagulated powder. And it has little relation with the particles shape, surface roughness and surface adsorbed layer at the fine powders.
The packing property has been studied by the tapping compressed method. The relationship between the apparent density of powder bed and the tapping frequency can be correlated to Kuno's equation.
The packing coefficient k1 at the first stage of packing corresponds to the constant b of Kawakita's equation, that is related to the coagulation force of powder. The k1 decreases with the particle size, and take minimum value at about 3μ, and then it increases again. These results suggest that the unit particles will build up the coagulated secondary particle, and the static properties of fine powders are influenced by the characteristics of the coagulated particles.