Impact of a tert-butyl alcohol-cyclohexane system used in unidirectional freeze-casting of SiOC on compressive strength and mass transport

Braun, Pedro Henrique da Rosa; Rezwan, Kurosch; Wilhelm, Michaela

doi:10.1016/j.matdes.2021.110186

Cited by 7 publications

(1 citation statement)

References 32 publications

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“…Ice templating is the basis of structure formation when porous materials or cellular solids are manufactured by freeze casting, a processing technique based on the directional solidification of aqueous solutions and slurries. While also other solvents, such as camphene, [ 1 ] cyclohexane, [ 1d,2 ] tert ‐butyl alcohol (TBA), [ 1d,2 ] TBA‐cyclohexane, [ 3 ] and naphthalene‐camphor, [ 4 ] have been directionally solidified and the solvent‐templated structures have been investigated, water‐based systems continue to be the most widely used for materials processing. What remains little explored and understood in the case of all solvents, to date, are the complex dynamics of solvent crystal growth and templating during directional solidification.…”

Section: Introductionmentioning

confidence: 99%

X‐Ray Tomoscopy Reveals the Dynamics of Ice Templating

Kamm,

Yin,

Neu

et al. 2023

Adv Funct Materials

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Little experimentally explored and understood are the complex dynamics of microstructure formation by ice‐templating when aqueous solutions or slurries are directionally solidified (freeze cast) into cellular solids. With synchrotron‐based, time‐resolved X‐ray tomoscopy it is possible to study in situ under well‐defined conditions the anisotropic, partially faceted growth of ice crystals in aqueous systems. Obtaining one full tomogram per second for ≈270 s with a spatial resolution of 6 µm, it is possible to capture with minimal X‐ray absorption, the freezing front in a 3% weight/volume (w/v) sucrose‐in‐water solution, which typically progresses at 5–30 µm s−1 for applied cooling rates of = 1–10 °C min−1. These time and length scales render X‐ray tomoscopy ideally suited to quantify in 3D ice crystal growth and templating phenomena that determine the performance‐defining hierarchical architecture of freeze‐cast materials: a complex pore morphology and “ridges”, “jellyfish cap”, and “tentacle”‐like secondary features, which decorate the cell walls.

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Section: Introductionmentioning

confidence: 99%

X‐Ray Tomoscopy Reveals the Dynamics of Ice Templating

Kamm,

Yin,

Neu

et al. 2023

Adv Funct Materials

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Influence of the 3D architecture and surface roughness of SiOC anodes on bioelectrochemical system performance: a comparative study of freeze-cast, 3D-printed, and tape-cast materials with uniform composition

da Rosa Braun,

Kuchenbuch,

Toselli

et al. 2024

Mater Renew Sustain Energy

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Abstract3D-printed anodes for bioelectrochemical systems are increasingly being reported. However, comparisons between 3D-printed anodes and their non-3D-printed counterparts with the same material composition are still lacking. In addition, surface roughness parameters that could be correlated with bioelectrochemical performance are rarely determined. To fill these gaps, slurries with identical composition but different mass fractions were processed into SiOC anodes by tape-casting, freeze-casting, or direct-ink writing. The current generation was investigated using electroactive biofilms enriched with Geobacter spp. Freeze-cast anodes showed more surface pores and the highest surface kurtosis of 5.7 ± 0.5, whereas tape-cast and 3D-printed anodes showed a closed surface porosity. 3D-printing was only possible using slurries 85 wt% of mass fraction. The surface pores of the freeze-cast anodes improved bacterial adhesion and resulted in a high initial (first cycle) maximum current density per geometric surface area of 9.2 ± 2.1 A m−2. The larger surface area of the 3D-printed anodes prevented pore clogging and produced the highest current density per geometric surface area of 12.0 ± 1.2 A m−2. The current density values of all anodes are similar when the current density is normalized over the entire geometric surface as determined by CT-scans. This study highlights the role of geometric surface area in normalizing current generation and the need to use more surface roughness parameters to correlate anode properties, bacterial adhesion, and current generation.

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