抄録
The mechanism of deagglomerant and glidant additives on the physical characteristics of powdered material has been investigated experimentally by means of several kinds of measuring methods. Limestone, sillica sand and fused alumina have been selected as powdered materials, and colloidal silica, calcium stearate and magnesium oxide as additive agents.
The results of measurement by split cell type tensile strength method reveal that the additives decrease the adhesion force of powder when the powder is strongly adhesive (limestone, Figs. 7, 8), and increase the force when it is less adhesive (fused alumina, Fig. 9).
On the contrary, the results of measurement by shear strength method make it clear that the mixing of additive agent increases the internal frictional coefficient of powdered materials regardless of the kinds of additives (Fig. 10, Table II).
From these two measuring methods, the mechanism of additive agents is assumed as follows. Ultra fine solid particles of additives are attached to the surface of larger particle, making it rough enough to increase friction coefficient and to decrease the adhesion force of large particle. In the latter case, the authors have already pointed out in a preceeding report on the measurement by centrifugal separating method3)11).
The effects of additive agent on the angle of repose and on the packing property, which are complex compound of the two fundamental characteristics of powder mentioned above, are naturally neither clearly shown nor thought to be so simple, according to the experimental results as are shown in Figs. 2∼6, Table I.
