An Evaluation of Sphericity of Convex Particle

Abstract

Digital image processing technique with various threshold levels was applied for a single particle to collect three-dimensional parameters such as particle volume and sphericity. The volume of a sampled particle measured from various directions was different because of the extrusions on the surface. However, the cross-sectional shapes of a particle were reflected on the images obtained by varying the threshold levels since the minimum volume measured by the present technique was in agreement with the volume obtained through the measurement of buoyancy with an accuracy of 0.1 cubic millimeter. Subsequently, in order to evaluate the three-dimensional shape of fractioned particles, the degree of deviation from a sphere, the normalization of which gives the sphericity, was introduced. The practical usefulness of present technique was demonstrated for a spherical aluminum dioxide granule.