Self–Foamed Cellular Ceramics from Silicone Resins with a Zeolite Surface

Scheffler, Michael; Gambaryan‐Roisman, Tatiana; Zeschky, J.; Scheffler, Franziska; Greil, Peter

doi:10.1002/9780470294758.ch23

Cited by 11 publications

(12 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The latter case results in the formation of hydrogen (H 2 ) gas that can be used as to “self blow” the system to obtain porous components23242829. In the present experiments, the heat applied from the bottom of the aluminum mold initiated the crosslinking reactions, simultaneously the gas bubbles nucleated probably with the aid of LDH particles (both as a surface and water including source), expelled from the heated surface and moved into the cooler zone till reaching to the upper surface (atmospheric).…”

Section: Resultsmentioning

confidence: 99%

“…In the present experiments, the heat applied from the bottom of the aluminum mold initiated the crosslinking reactions, simultaneously the gas bubbles nucleated probably with the aid of LDH particles (both as a surface and water including source), expelled from the heated surface and moved into the cooler zone till reaching to the upper surface (atmospheric). Additional experiments (not shown for the brevity) in which the crosslinking was conducted in the oven (uniform heating) instead of hot-plate directional heating, foams with no aligned porosity were obtained222428. This implies that the formation of aligned channels was caused by the temperature gradient from bottom to top resulting in simultaneous curing and gas release together with the coalescence of gas bubbles during raise, yielding larger channels on the top.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Gradient-Hierarchic-Aligned Porosity SiOC Ceramics

Vakifahmetoğlu

Zeydanlı

Innocentini

et al. 2017

Sci Rep

View full text Add to dashboard Cite

This work describes a simple technique to produce porous ceramics with aligned porosity having very high permeability and specific surface area. SiOC-based compositions were processed from blends of three types of preceramic polymer and a catalyst, followed by curing and pyrolysis. The heating applied from the bottom of molds promoted the nucleation, expansion and rising of gas bubbles, and the creation of a ceramic matrix with axially oriented channels interconnected by small round pores. The samples were analyzed by SEM, tomography, BET, water immersion porosimetry and permeation to gas flow. The resulting bodies presented levels of open porosity (69.9–83.4%), average channel diameter (0.59–1.25 mm) and permeability (0.56–3.83 × 10−9 m2) comparable to those of ceramic foams and honeycomb monoliths, but with specific surface area (4.8–121.9 m2/g) typical adsorbents, enabling these lotus-type ceramics to be advantageously used as catalytic supports and adsorption components in several environmental control applications.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Gradient-Hierarchic-Aligned Porosity SiOC Ceramics

Vakifahmetoğlu

Zeydanlı

Innocentini

et al. 2017

Sci Rep

View full text Add to dashboard Cite

show abstract

“…The foaming process of those open-cellular materials from silicone resins was developed for the manufacture of ceramic foams and is described in ref. [22][23][24] As photocatalytic active filler particles Aerosol TiO 2 P25 (Degussa GmbH, Hanau, Germany) with a specific surface area of 50 AE 15 m 2 Á g À1 and an average particle size d 50 of 21 nm was used.…”

Section: Materials Processingmentioning

confidence: 99%

Novel‐Type Inorganic Foams from Preceramic Polymers with Embedded Titania Nanoparticles for Photo‐Catalytic Applications

et al. 2011

View full text Add to dashboard Cite

Photocatalytic active silica‐based foams were prepared by embedding nanotitania (anatase) into a self‐foaming glass particle‐loaded preceramic polymer and then thermally converting it in air into a silica‐based material. The foaming behavior of the mixture was found to be influenced by the volume fraction of the filler materials, resulting in open‐cellular or fused composite materials. Transformation from the anatase modification into the rutile modification is prevented even at 800 °C by the formation of SiOTi bonds. The composite foam structure with embedded nanotitania was tested in methylene blue decomposition under UV irradiation and it was found to have higher photocatalytic activity compared to unsupported nanotitania.

show abstract

“…Therefore, particles, compounds or other substances are often added to metallic foam to increase the apparent liquid viscosity and to slow down the rupture process (Banhart 2001;Yang & Nakae 2003). Ceramic foams are produced from polymer melts by the condensation and the reaction products formed during cross-linking (Scheffler et al 2002). The dynamics of the polymer foams are strongly dependent on the temperature.…”

Section: Introductionmentioning

confidence: 99%

The thinning of lamellae in surfactant-free foams with non-Newtonian liquid phase

Brush¹,

Roper²

2008

J. Fluid Mech.

View full text Add to dashboard Cite

Thinning rates of liquid lamellae in surfactant-free non-Newtonian gas-liquid foams, appropriate for ceramic or polymer melts and also in metals near the melting point, are derived in two dimensions by matched asymptotic analysis valid at small capillary number. The liquid viscosity is modelled (i) as a power-law function of the shear rate and (ii) by the Ellis law. Equations governing gas-liquid interface dynamics and variations in liquid viscosity are derived within the lamellar, transition and plateau border regions of a corner of the liquid surrounding a gas bubble. The results show that the viscosity varies primarily in the very short transition region lying between the lamellar and the Plateau border regions where the shear rates can become very large. In contrast to a foam with Newtonian liquid, the matching condition which determines the rate of lamellar thinning is non-local. In all cases considered, calculated lamellar thinning rates exhibit an initial transient thinning regime, followed by a t −2 power-law thinning regime, similar to the behaviour seen in foams with Newtonian liquid phase. In semi-arid foam, in which the liquid fraction is O(1) in the small capillary number, results explicitly show that for both the power-law and Ellis-law model of viscosity, the thinning of lamella in non-Newtonian and Newtonian foams is governed by the same equation, from which scaling laws can be deduced. This result is consistent with recently published experimental results on forced foam drainage. However, in an arid foam, which has much smaller volume fraction of liquid resulting in an increase in the Plateau border radius of curvature as lamellar thinning progresses, the scaling law depends on the material and the thinning rate is not independent of the liquid viscosity model parameters. Calculations of thinning rates, viscosities, pressures, interface shapes and shear rates in the transition region are presented using data for real liquids from the literature. Although for shear-thinning fluids the power-law viscosity becomes infinite at the boundaries of the internal transition region where the shear rate is zero, the interface shape, the pressure and the internal shear rates calculated by both rheological models are indistinguishable.

show abstract

Self–Foamed Cellular Ceramics from Silicone Resins with a Zeolite Surface

Cited by 11 publications

References 0 publications

Gradient-Hierarchic-Aligned Porosity SiOC Ceramics

Gradient-Hierarchic-Aligned Porosity SiOC Ceramics

Novel‐Type Inorganic Foams from Preceramic Polymers with Embedded Titania Nanoparticles for Photo‐Catalytic Applications

The thinning of lamellae in surfactant-free foams with non-Newtonian liquid phase

Contact Info

Product

Resources

About