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Unidirectional Freezing of Ceramic Suspensions: In Situ X‑ray Investigation of the Effects of Additives

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journal contribution
posted on 2014-01-08, 00:00 authored by Benjamin Delattre, Hao Bai, Robert O. Ritchie, Joël De Coninck, Antoni P. Tomsia
Using in situ X-ray radiography, we investigated unidirectional freezing of titanium dioxide suspensions. We showed how processing additives, which are generally used for ice-templating, strongly modified freezing dynamics during the solidification process. We observed and identified different freezing regimes by varying the amount of dispersant, binder, or poly­(ethylene glycol) (PEG). We demonstrated that because each regime corresponds to a given final structure understanding the particle motion and redistribution at the ice-front level was essential. We also examined the transition from a random particles-entrapment regime to a well-defined lamellar regime and proposed and discussed two mechanisms by which additives might affect the solidification process.