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Compacting and aging of powders : influence of the formulation

Abstract : This study is conducted in the framework of the “PowderReg” project, funded by the European program Interreg VA GR within the priority axis 4 “Strengthen the competitiveness and the attractiveness of the Grande Région Groβregion”. Understanding the link between microscopic organization and powders flow behavior is a major step forward in establishing criteria for optimizing their transport, storage and processing properties. Whereby, better understating of powder flow behavior saves the industries from huge economic loss. Therefore, it is essential to evaluate their flowability. This work consists in experimentally studying the influence of powder formulation, particle size, as well as influence of environmental condition such as humidity on flow behaviors of powders. Five types of formulations have been analyzed: control glass bead has been used as reference powder and three types of surface formulations consisting of hydrophilic, hydrophobic and lactose coating as well as agglomerated lactose powder have been prepared. First, influence of two different sizes 100 and 500 µm on flow behavior of powders has been analyzed. Then, the powders flow behavior has been considered with different experimental equipements: FT4, Granutools and Rheometer Discover HR3. Including different techniques, such as shear cell, compressibility, rotating angle of repose, etc. The objective was to figure out the behavior of powders under different processing conditions. The, results reported that the transition from one technique to another can modify the classification of the powder flowability. Since the powders were experiencing different mechanical stresses. At the last part of this thesis, we observed the impressive influence of humidity after 80 % on flow behavior of two different size of control glass beads (40 and 100 µm). Small diameter glass bead showed lower flowability which is due to the more surface contacts of these particles. Furthermore, the comparison of flow behavior of control and hydrophobic glass beads with 100 µm size at high shear rate reported the same flowability for both samples. While at low shear rate measurements by vibrational rheology revealed higher flowability in control glass bead. The flowability of control glass bead decreased dramatically after 80 % of humid control, however hydrophobic formulated glass bead kept its flow behavior like as before with very low sensitivity to humidity. Finally, influence of addition of small quantity of water on flow behavior of control glass bead has been investigated.
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Submitted on : Tuesday, April 20, 2021 - 4:59:52 PM
Last modification on : Wednesday, November 3, 2021 - 7:10:25 AM


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Shirin Enferad. Compacting and aging of powders : influence of the formulation. Fluid mechanics [physics.class-ph]. Université de Lorraine, 2020. English. ⟨NNT : 2020LORR0214⟩. ⟨tel-03203307⟩



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