Freeze cast fabrication of porous ceramics using tert -butyl alcohol–water crystals as template

Tang, Yufei; Qiu, Sha; Wu, Cong; Qian, Miao; Zhao, Kang

doi:10.1016/j.jeurceramsoc.2015.12.047

Cited by 54 publications

(29 citation statements)

References 27 publications

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“…Freeze casting techniques (a special sacrificial templating method) create porosity by freezing a stable suspension at low temperatures during which the freezing solvent pushes the suspended ceramic particles away from the frozen front . This near‐net shape and powerful technique has been widely used to produce bulky macroporous monoliths having different pore shapes by using water, camphene, or tert‐butyl alcohol or mixtures as the sublimate medium . Additionally, additives can influence the final pore morphology of the monolith …”

Section: Introductionmentioning

confidence: 99%

“…14 This near-net shape and powerful technique has been widely used to produce bulky macroporous monoliths having different pore shapes by using water, camphene, or tert-butyl alcohol or mixtures as the sublimate medium. [14][15][16][17][18] Additionally, additives can influence the final pore morphology of the monolith. 19 Polymer-derived ceramics (normally SiC, SiCN, SiOC, etc.)…”

Section: Introductionmentioning

confidence: 99%

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Water‐based freeze casting: Adjusting hydrophobic polymethylsiloxane for obtaining hierarchically ordered porous SiOC

et al. 2017

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The hydrophobic properties of methyl poly siloxane (MK) were pushed into the “hydrophilic” range by cross‐linking it with (3‐aminopropyl)triethoxysilane (APTES) and subsequent pyrolysis to enable water‐based freeze casting. Filler properties are investigated by varying the ratios of MK to APTES (1:1, 1:2, 1:3, 1:4, 1:5), and pyrolysis temperatures (400°C, 500°C, 600°C) for the purpose of determining an optimal set of characteristics for freeze casting. Additionally, filler selection for this purpose is facilitated by analysis of zeta potential values and vapor adsorption. It was found that water‐based freeze casting with hybrid fillers, followed by a pyrolysis step (600°C‐700°C), leads to a SiOC ceramic monolith with a lamellar pore morphology and a hierarchically ordered micro/meso/macropore structure. Samples pyrolyzed at 1000°C contain mesopores, having a SSA as high as 51.6 m2/g. The hierarchically porous structure is very promising for applications involving gas or liquid transportation.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Water‐based freeze casting: Adjusting hydrophobic polymethylsiloxane for obtaining hierarchically ordered porous SiOC

et al. 2017

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“…The dimensions of the macropores thus depend on the size of the ice crystals and are typically of the order ∼1 µm to ∼100 µm . While water is the most common solvent, alternatives such as camphene or tert ‐butyl alcohol have been used successfully, however, with different solidification temperatures and altered morphologies. With no temperature control other than that of a specific coolant, the macropore dimensions are typically graded throughout the structures being smaller at the bottom than at the top.…”

Section: Introductionmentioning

confidence: 99%

“…CHRISTIANSEN ET Al. alcohol 7 have been used successfully, however, with different solidification temperatures and altered morphologies. With no temperature control other than that of a specific coolant, the macropore dimensions are typically graded throughout the structures being smaller at the bottom than at the top.…”

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confidence: 99%

The effect of gelation on statically and dynamically freeze‐cast structures

et al. 2019

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Freeze‐casting is a technique used to produce structures with anisotropic porosity in the form of well‐defined microchannels throughout a sample. Here, this technique is used on the magnetocaloric ceramic La0.66Ca0.26Sr0.07 Mn1.05O3. We show that a dynamic freezing profile, where the temperature is decreased continuously at −10 K/min, results in homogeneous, lamellar channels with widths of ∼15 µm, while static freezing, where the temperature is kept constant at 177 K, results in channels of increasing size away from the initial ice crystal nucleation site. The effect of gelation before freeze‐casting is also investigated. Gelation inhibits ice crystal growth, which significantly changes the morphology by making channel cross sections less elongated, while additionally introducing more dendrites and ceramic bridges in the structure. The latter significantly dominates the flow path through the gelated structures, affecting the calculated tortuosity, which increases to τ ≈ 4 when compared to non‐gelated samples where calculated tortuosities are in the range of ∼1.3 to ∼3. Finally, we present a systematic and automatic approach for evaluating channel and wall sizes and calculating tortuosities. This is based on analysis of images obtained by scanning electron microscopy using a continuous particle size distribution method and the TauFactor application in MATLAB®.

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“…Porous purging materials have been widely used in the fields of metallurgy, chemical industry, environmental protection, porous burner, etc Obviously, excellent gas permeability of the porous material is one of the basic premises for its functional applications. There are many methods to prepare porous materials, including particle packing , pore‐forming agent methods, sacrificial template methods, freeze‐drying processes, and gel casting . Porous materials of particle‐packing type facile manufacturing, excellent gas permeability, and high mechanical strength.…”

Section: Introductionmentioning

confidence: 99%

Correlations between pore structure parameters and gas permeability of corundum porous materials

Xiong

Wang

et al. 2019

J Am Ceram Soc

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Corundum porous materials with different contents of calcium hexaluminate formed in situ were prepared using pure calcium aluminate cement as the calcium source. The surface fractal dimensions of the porous materials were calculated based on the experimental data of mercury intrusion. Correlations between pore structural parameters and the permeability coefficients k1 and k2 of the porous materials were then studied based on the grey system theory. The results showed that pores in the corundum porous materials have great fractal characteristics. The surface fractal dimension was a significant pore structural parameter that reflected the complexity of pore shape, pore surface, and pore‐size distribution, which had the maximum correlation coefficient with the permeability of this type of porous materials. The apparent porosity and pore‐size distribution had relatively high correlation coefficients to the permeability as well. Increasing the apparent porosity and the volume percentage of larger pores, and decreasing the volume percentage of smaller pores all benefited the permeability of the porous materials. In addition, the mean pore size and median pore size showed lower correlation coefficients to the permeability—especially for porous materials with a wide pore‐size distribution.

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Freeze cast fabrication of porous ceramics using tert -butyl alcohol–water crystals as template

Cited by 54 publications

References 27 publications

Water‐based freeze casting: Adjusting hydrophobic polymethylsiloxane for obtaining hierarchically ordered porous SiOC

Water‐based freeze casting: Adjusting hydrophobic polymethylsiloxane for obtaining hierarchically ordered porous SiOC

The effect of gelation on statically and dynamically freeze‐cast structures

Correlations between pore structure parameters and gas permeability of corundum porous materials

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