The Sevilla Powder Tester: A Tool for Characterizing the Physical Properties of Fine Cohesive Powders at Very Small Consolidations

Abstract

We present a fluidized bed apparatus that enables us to test the bulk mechanical properties such as the yield stresses and compressibility of fine cohesive powders. Every measurement is preceded by driving the powder into the bubbling regime in which the material loses memory of its previous history. Then the gas flow is set to a given value to take the powder into a well defined and reproducible initial state of low consolidation. Reverse flow is used to exert high compressive stress. A cornerstone of our technique is that the procedure is automatized, thus making results operator insensitive. Besides being a practical tool to diagnose the flowability of experimental powders, the Sevilla Powder Tester (SPT) also provides us with a powerful technique to research fundamental problems in powder mechanics.