Our work describes an optimised procedure for granulating nanometric and fine micrometric particles by spray-drying to achieve ready-to-print α-Al2O3 powders. The study started by identifying raw materials suited for the process through complete characterisation of particles shape, size, and surface properties. Then, dispersion in diluted and concentrated water-based suspensions was achieved thanks to polyethyleneimine and the effect of gradual dispersant addition was assessed by determining ζ potential and aggregates size variation. Suspensions rheology was studied and modelled through Krieger-Dougherty equation to identify the maximum solid loading allowing sufficient feeding through the spray-dryer nozzle. Finally, optimisation of the granulation conditions was performed. The procedure has allowed to achieve size distributions with D90 < 50 μm and Hausner ratio <1.3 ensuring sufficient flowability. The granulated powders were printed and the porosity evolution of the samples after sintering was studied by mercury intrusion porosimetry and SEM analysis.

Tailoring α-alumina powder morphology through spray drying for cold consolidation by binder jetting

Mariani M.;Galassi C.;Lecis N.;
2022-01-01

Abstract

Our work describes an optimised procedure for granulating nanometric and fine micrometric particles by spray-drying to achieve ready-to-print α-Al2O3 powders. The study started by identifying raw materials suited for the process through complete characterisation of particles shape, size, and surface properties. Then, dispersion in diluted and concentrated water-based suspensions was achieved thanks to polyethyleneimine and the effect of gradual dispersant addition was assessed by determining ζ potential and aggregates size variation. Suspensions rheology was studied and modelled through Krieger-Dougherty equation to identify the maximum solid loading allowing sufficient feeding through the spray-dryer nozzle. Finally, optimisation of the granulation conditions was performed. The procedure has allowed to achieve size distributions with D90 < 50 μm and Hausner ratio <1.3 ensuring sufficient flowability. The granulated powders were printed and the porosity evolution of the samples after sintering was studied by mercury intrusion porosimetry and SEM analysis.
2022
Binder jetting, Alumina, Spray drying granulation
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/1228598
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