Permeability of Compacted Powders Determination of Average Pore Size

Abstract

With air as the diffusing medium a method and apparatus have been developed for measuring the permeability of compacted, unconsolidated powders. A formula is given for calculating the average pore diameter from the permeability and the percent of voids in the compacted powder. By establishing a simple relationship between the degree of packing, as measured by the percent voids, and the average individual pore diameter it is possible to calculate the pore size in a comminuted solid for any degree of compaction. When liquids (e.g., bitumen, sulfur, etc.) are stabilized by the addition of solid particles, the degree of packing of the particles and the dimensions of the films and masses of liquid separating them exert a profound influence on the consistency of the mixture. Thus, a knowledge of the average pore diameter of a powder as present in a solid-liquid system is of practical value. The influence of average particle size on average pore diameter was studied and data are presented for silica and slate powders.