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Optimization of ceramic slurries for spray drying yielding non-hollow granules

  • Economic industrial spray drying of ceramic slurries aims for as high as possible solids content. Investigated slurries of up to 80 wt% solids content were analyzed regarding stability while staying processable for granule production via spray drying. Preliminary stability examinations were carried out on the one hand via zeta potential measurements and on the other hand by optical centrifuge analysis for determination of suitable additive type, quantity and composition while even allowing the detection of potential side effects. The processability of the slurry for spraying has primarily been quantified by viscosity measurements. Early spray dried granules turned out to have internal voids and/or hard shells leading to defective sinter bodies and low density. Focusing on the root of these voids, the “hollow hard granules”, a controlled destabilization and flocculation was initiated by weakening electrostatic repulsion and approaching the isoelectric point. Destabilization,Economic industrial spray drying of ceramic slurries aims for as high as possible solids content. Investigated slurries of up to 80 wt% solids content were analyzed regarding stability while staying processable for granule production via spray drying. Preliminary stability examinations were carried out on the one hand via zeta potential measurements and on the other hand by optical centrifuge analysis for determination of suitable additive type, quantity and composition while even allowing the detection of potential side effects. The processability of the slurry for spraying has primarily been quantified by viscosity measurements. Early spray dried granules turned out to have internal voids and/or hard shells leading to defective sinter bodies and low density. Focusing on the root of these voids, the “hollow hard granules”, a controlled destabilization and flocculation was initiated by weakening electrostatic repulsion and approaching the isoelectric point. Destabilization, quantifiable by optical centrifugation, leaded to a change in speed of clarification as well as packing density, influencing movement speed of the phase boundary and the final height of the sediment, respectively. For sufficient destabilization, the solids content needed to be reduced in order to keep the viscosity suitable for the following spray drying procedure. The versatile controlled destabilization of the ceramic slurry finally leaded to a significantly reduced fraction of hollow granules featuring a sinter body of higher density with smaller pores and a narrower pore size distribution, additionally this destabilization approach has shown to be transferrable with excellent results to zirconia and even ZTA (zirconia toughened alumina) composite materials.zeige mehrzeige weniger

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Metadaten
Autoren/innen:Patrick Höhne
Koautoren/innen:Petra Kuchenbecker, Franziska Lindemann, Wolfgang Güther, Christian Neumann, Torsten Rabe
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2016
Organisationseinheit der BAM:5 Werkstofftechnik
5 Werkstofftechnik / 5.5 Technische Keramik
DDC-Klassifikation:Naturwissenschaften und Mathematik / Chemie / Analytische Chemie
Freie Schlagwörter:ceramics; granulation; microstructure; slurry; spray drying
Themenfelder/Aktivitätsfelder der BAM:Analytical Sciences
Analytical Sciences / Oberflächen- und Grenzflächenanalytik
Veranstaltung:International Workshop Dispersion Analysis & Materials Testing 2016
Veranstaltungsort:Berlin, Germany
Beginndatum der Veranstaltung:26.09.2016
Enddatum der Veranstaltung:27.09.2016
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:13.10.2016
Referierte Publikation:Nein