抄録
To evaluate rheological characteristics of surface-modified particles and powders containing a small amount of additives, the authors developed a novel shear test method for a powder bed, a rotary intrusion method with a conical rotor. In the method, a rotating circular cone having grooves on its surface intrudes into a powder bed and shears it, and the relationship between the shear torque exerting the conical rotor and the depth to which the rotor intruded, i.e., the shear characteristics curve, was measured. The apparent viscosity of a powder, which expresses a subtle change of rheological characteristics based on a slight variation of surface characteristics of particles, could be determined from the shear characteristics curves. The rheological characteristics depend strongly on the motion of particles within a shear layer because the particles move complicatedly while rotating and sliding. In this study, the influences of physical properties of particles on the rheological characteristics have been investigated by analyzing the particle motion within a shear layer during intrusion of the conical rotor, which is expressed in a three dimensional region by means of the discrete element method (DEM). By calculating the shear characteristics curves under various physical properties of particles, we have clarified that the particle motion (rotating and sliding) within a shear layer takes an important role in the determination of rheological characteristics of powder.
