Rheology of Powders: Assessing the Robustness and Impact of Humidity, Tribocharging, Particle Size and Composition

摘要

Many powder metallurgy (PM) processes rely on powder flowability to ensure the productivity and stability of manufacturing process and the quality of the final parts. Different methods have been developed to quantify powder flow behavior under different conditions (Hall flow, Carney flow, angle of repose, powder rheometer, avalanche, etc.). Powder rheology, which measures the resistance seen by an impeller when moving through a cylinder filled with powder, has recently generated interest in the PM community. In order to use the method for quality control, certification, simulation and R&D purposes, it is important to evaluate the robustness of the method and investigate the effect of experimental conditions and particle characteristics on the measurements. This paper presents an assessment of the variability of the results using a commercial rheometer and an evaluation of the impact of humidity, measurement vessel, charging and powder characteristics (size distribution and composition) on the measurements. Results were compared with values obtained using Hall and Carney flowmeters.