Characterization of a Particle by a Pair of Shape Indexes

In order to evaluate the shape characteristics of a particle in more detail, the characterization of the particle projection was discussed by a pair of shape indices: the macroscopic shape index δ and the microscopic one ζ.In the present work, δ and ζ were defined as follows. δ is the degree of circularity of the equivalent ellipse which has the same projection area and the same ratio of the maximum length to the breadth as the original particle projection, and ζ is the ratio of the perimeter of the particle projection to that of the equivalent ellipse. It expresses the degree of roughness of the particle periphery. Several kinds of model pictures and projections of granules of different shapes were characterized by the shape indices.As a result, it was concluded that the pair of shape indices, defined in the present paper, could be one of the effective measures for the shape characterization of particle.