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  4. Unidirectional solution-based freeze cast polymer-derived ceramics: influence of freezing conditions and templating solvent on capillary transport in isothermal wicking
 
Zitierlink DOI
10.26092/elib/2481
Verlagslink DOI
10.1007/s10853-019-04310-0

Unidirectional solution-based freeze cast polymer-derived ceramics: influence of freezing conditions and templating solvent on capillary transport in isothermal wicking

Veröffentlichungsdatum
2019-12-23
Autoren
Schumacher, Daniel  
da Rosa Braun, Pedro Henrique  
Wilhelm, Michaela  
Rezwan, Kurosch  
Zusammenfassung
Porous SiOC monoliths were prepared by solution-based freeze casting of polysiloxane at constant freezing temperature or constant freezing front velocity. Dendritic and prismatic pore structures were obtained by using cyclohexane and tert-butyl alcohol as solvent, respectively. Gradients in freezing velocity lead to gradients in pore window size, whereas a constant freezing velocity (3.3–6.8 µm/s) generates homogeneous pore structures. The water permeability varies from 1.12 × 10−13 to 1.03 × 10−11 m2 and correlates with the pore window diameter (10–59 µm) and the porosity (51–82%). In wicking tests, the gradient in pore window size is clearly reflected by a pronounced decrease in the wicking speed. Contrary, a homogeneous pore structure results in wicking curves which are closer to the prediction according to the Lucas–Washburn equation. However, this theoretical approach based on the three parameters, pore window size, porosity and permeability, is insufficient to describe complex three-dimensional pore structures. Besides the porosity, the pore morphology was found to be a major influencing factor on the wicking. The filling of secondary dendrites slows down the wicking into the dendritic structure. Fastest wicking was observed for a prismatic pore structure at low freezing front velocity (6.6 µm/s) and high porosity (78%), whereas slowest wicking occurred into the dendritic structure with high porosity (76%) and constant freezing temperature (− 20 °C). The knowledge of the relationship between structural properties and the resulting wicking behavior can address a variety of pivotal applications in chemical engineering for capillary transport.
Schlagwörter
Mimenima
Verlag
Springer
Institution
Universität Bremen  
Fachbereich
Zentrale Wissenschaftliche Einrichtungen und Kooperationen  
Institute
MAPEX Center for Materials and Processes  
Dokumenttyp
Artikel/Aufsatz
Zeitschrift/Sammelwerk
Journal of Materials Science  
Band
55
Startseite
4157
Endseite
4169
Zweitveröffentlichung
Ja
Dokumentversion
Postprint
Lizenz
Alle Rechte vorbehalten
Sprache
Englisch
Dateien
Lade...
Vorschaubild
Name

D. Schumacher, P.H. da Rosa Braun, M. Wilhelm, K. Rezwan, Unidirectional solution-based freeze cast polymer-derived ceramics_influence_2019_accepted_version_Deckblatt_pdfa1.pdf

Size

2.11 MB

Format

Adobe PDF

Checksum

(MD5):bec98913d20aba8aabbf36cc440b3e13

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