Increased Mechanical Stability and Thermal Conductivity of Alumina Reticulated Porous Ceramics (RPC) by Nanoparticle Infiltration Processing

Rannabauer, Stefan; Söffker, Gerrit-Maximilian; Scheunemann, Marcel; Betke, Ulf; Scheffler, Michael

doi:10.1002/adem.201700211

Cited by 28 publications

(25 citation statements)

References 23 publications

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“…The intrusion rate plots (incremental pore volume) have several peaks, which are representing a specific order of porosity included in replica‐foams. According to Rannabauer et al, the porosity of replica‐foams is divided by four orders of magnitude: the cell pores (1st order), the cavities inside the hollow struts (2nd order), the cracks and microstructure defects (3rd order) that are the assesses to the hollow struts, and the intrinsic materials porosity, addressed as 4th order of porosity.…”

Section: Resultsmentioning

confidence: 99%

Hierarchical‐Porous Ceramic Foams by a Combination of Replica and Freeze Technique

Schelm

Fey²,

Dammler

et al. 2019

Adv Eng Mater

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Open-porous alumina foams with additional strut porosity are fabricated by a two-step sponge-replication based manufacturing process. As the first step, open cellular ceramic foams are prepared following the Schwarzwalder sponge replication technique. Therefore, organic foam templates are coated with different aqueous alumina slurries with a solid load between 20 and 40 vol% In a second step, an additional porosity is generated inside the foam struts by freezing of the foams at temperatures between À196 and À20 C and subsequent sublimation drying. The hierarchical structure of both, cell pores and strut pores in the freeze-dried material remains intact after drying, template removal, and sintering. Size, connectivity, and morphology of the strut pores strongly depend on the solid load of the alumina slurry and on the freezing temperature. Cellular structures with a strut porosity between 50% and 60% and a total porosity exceeding 90% are prepared, which show a compressive strength in between 0.4 to 0.6 MPa. Due to the additional strut porosity, the specific surface area of freeze-dried replica foams increases from 70 cm 2 g À1 for conventionally prepared foams to 200 cm 2 g À1 for freeze-dried foams, respectively.

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Section: Resultsmentioning

confidence: 99%

Hierarchical‐Porous Ceramic Foams by a Combination of Replica and Freeze Technique

Schelm

Fey²,

Dammler

et al. 2019

Adv Eng Mater

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“…An average compressive strength σ fc of 0.15 ± 0.03 MPa and a Weibull modulus m of 5.6 were calculated ( Figure 7). e modulus m is in the expected range for brittle cellular ceramic structures [37,38]. Essentially, the low compressive strength is a consequence of the high porosity of 93.6% in the ZnO ceramic foams; accordingly, the σ fc value is in the same order of magnitude as the compressive strength of cellular alumina with a similar microstructure and porosity range (σ fc � 0.19 MPa/0.34 MPa at 94.0%/93% total porosity) [37].…”

Section: Mechanical and Ermal Properties Of Zno Ceramic Foamsmentioning

confidence: 91%

Reticulated Open-Celled Zinc Oxide Ceramic Foams: Manufacturing, Microstructure, Mechanical, and Thermal Properties

Betke

Scheffler

2019

Advances in Materials Science and Engineering

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Open-celled zinc oxide ceramic foams were prepared by the polymer sponge replication (Schwartzwalder) technique from aqueous ZnO dispersions with Sb2O3 and Bi2O3 as sintering additives, and mechanically stable ZnO foams with an average porosity of 93.6% were obtained. Their microstructure consists of ZnO grains with a Bi-containing grain boundary phase together with a Zn-Sb-O secondary phase with spinel structure. The obtained ZnO ceramic foams were characterized with respect to their morphology by computed tomography; in addition, the compressive strength and the thermal conductivity were determined, and the data were applied for modelling of the mechanical and thermal properties of the bulk ZnO strut material.

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“…[70] Alumina foams were immersed into a alumina slurry containing no binder and a solid load of 50-65 wt%. The influence of the alumina particle size in the immersion slurry as well as the microstructure of the starting foams on the infiltration success were investigated.…”

Section: Inner Strut Functionalizationmentioning

confidence: 99%

Reticulated Replica Ceramic Foams: Processing, Functionalization, and Characterization

et al. 2017

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Reticulated ceramic foams are used in a wide range of applications such as filters, catalyst supports, lightweight materials, energy absorptions materials, or as scaffolds for tissue engineering as the most common ones. Based on gaseous foaming processes of polymers, a stochastic distribution of closed pores is obtained. By reticulation processing thin foam windows are removed between cells turning a closed cell into an open cell structure. These foams are used as template for porous ceramics manufacturing: With different processing approaches, for example, with dip coating of a ceramic slurry and a subsequent (multistep) thermal treatment ceramic reticulate foams are obtained. A variety of material properties strongly depend on the cell and strut size, as well on material composition. Functionalization of ceramic foam surfaces (outer surface functionalization), for example, with zeolites or nanosized aggregates lead to an increase of the specific surface area or provides catalytic or heat storage functionality. Filling of struts (inner surface functionalization) may lead to improved mechanical stability or may provide functionalities such as electric conductivity. The present work summarizes the processing steps from the template foam to the final cellular ceramic, functionalization strategies, and the most common characterization techniques.

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Increased Mechanical Stability and Thermal Conductivity of Alumina Reticulated Porous Ceramics (RPC) by Nanoparticle Infiltration Processing

Cited by 28 publications

References 23 publications

Hierarchical‐Porous Ceramic Foams by a Combination of Replica and Freeze Technique

Hierarchical‐Porous Ceramic Foams by a Combination of Replica and Freeze Technique

Reticulated Open-Celled Zinc Oxide Ceramic Foams: Manufacturing, Microstructure, Mechanical, and Thermal Properties

Reticulated Replica Ceramic Foams: Processing, Functionalization, and Characterization

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