Development of a New Technique for Measuring Volume Change of Dry Particulate Systems Under Very Low Confining Pressures

Abstract

A new technique has been developed to measure volume change at very low confining pressures. Such low confining stress levels may be experienced in typical powder technology applications (storage and transport of particulate systems). The aim of this technique is to obtain more accurate information on the deformation, failure and flow behavior of cohesive powders under a variety of loading conditions and deformation rates. The technique allows covering the entire pressure regime that is covered by commercially available and industrially applied powder flow testers. It bridges the gap of multiple devices, whose ranges of test conditions do not overlap, thus facilitating cross-calibration of equipment and increases confidence (and reliability) of all compaction data obtained. The investigation of the effect of initial porosity on powder flowability was chosen to test the new experimental setup. In particular, triaxial tests have been carried out on samples of different particulate systems and the results have been presented at different confining pressures and on samples of different initial porosities.