Evaluating Porosity Parameters for Porosity–Property Relations

Abstract

Porosity parameters are considered from the standpoint of a map of the volume fraction porosity (P) and the ratio of normalized radii of the pore ( r p ) and the solid particles, webs, or ligaments ( r s ) defining the pores. For pore structures derived from uniform stacking of identical spherical particles or bubbles, this “map” turns out to be a single S‐shaped curve showing (1) very significant constraints on porosity variations achievable, and (2) r p / r s contains no information not already given by P , but (3) P or r p / r s do not fully characterize the porosity. Of other interrelated porosity factors, i.e, open vs closed or inter‐ vs intragranular nature, coordination number of the pores or particles, the shape (e.g., curvature) of the pores, and the minimal solid area (i.e., minimum web cross sections or the bond area between particles) representing some porosity characteristics independent of P or r p / r s , it is concluded that the minitics solid area is the most appropriate one. For more complex ideal and real pore structures, (1) the above map starts from the ideal P vs r p / r s curve at the two extremes of P (0 and 1), but becomes a moderate band in‐between, with the ideal P vs r p / r s curve at, or near, the mean of this band, and (2) a second parameter is still needed, and the minimum solid area is still the most appropriate one.