Influência das condições de processamento cerâmico na resistência mecânica e na permeabilidade dos filtros de Al2O3-SiC

Salvini, V. R.; Innocentini, M. D. M.; Pandolfelli, V. C.

doi:10.1590/s0366-69132002000300003

Cited by 6 publications

(4 citation statements)

References 2 publications

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“…Moreover, the porosity of the glass ceramic foams corresponds to that of commercially available PU sponges, which lies around 95%, independent of the number of pores. 24 Porosity is essential for determining ceramic foam performance. Mechanical strength generally decreases with increasing porosity, while permeability is improved, so that a compromise must be found 24 when the reticulated porous glass ceramic is intended to be used as a gas filter.…”

Section: Characterisation Of Glass Ceramic Foamsmentioning

confidence: 99%

LZSA glass ceramic foams prepared by replication process

Sousa¹,

Silveira²,

Fey³

et al. 2005

Advances in Applied Ceramics

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In this study the replication process was applied to produce porous glass ceramic foams. Polyurethane (PU) sponges were impregnated by immersion in aqueous slurry of a parent glass (mean particle size around 3 mm) from the system Li 2 O-ZrO 2 -SiO 2 -Al 2 O 3 and submitted to heat treatment. From TGA and IR analyses, two main paths of thermal decomposition of PU sponges were observed at 312 and 393uC, which were associated with the decomposition products CO 2 , CO, NH 3 and isocyanide. According to linear thermal shrinkage and DTA measurements, sintering starts at around 570uC and is completed below 700uC, when crystallisation takes place. The main crystalline phases identified by XRD analysis were zirconium silicate, lithium metasilicate and b-spodumene. The morphology and properties of the glass ceramic foams obtained from PU sponges were quite similar for all samples tested. From XCT measurements, a mean cell diameter of around 260 mm and mean strut thickness of 185 mm were calculated, corresponding to a porosity of 75-78%. Compressive strength values under 500 kPa and permeability coefficient in air of about 1000 Darcy were also measured for the samples tested. LZSA glass ceramic foams can be a very interesting alternative to ceramic gas filters, owing to low temperature processing, and to superior properties such as corrosion and thermal shock resistance.

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Section: Characterisation Of Glass Ceramic Foamsmentioning

confidence: 99%

LZSA glass ceramic foams prepared by replication process

Sousa¹,

Silveira²,

Fey³

et al. 2005

Advances in Applied Ceramics

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“…In this process, a polymeric foam is used as a template and is immersed in a ceramic slurry, where it is subsequently dried and sintered, yielding a close replica of the original polymeric foam [3]. Normally, the structural properties of the ceramic filter produced by this technique are mostly dictated by the characteristics of the polymer foam, such as the porosity, the pore size, and the number of pores per linear inch (PPI) [4,5]. Thus, characterization of the foams is crucial for the determination of their suitability under specific operational conditions, including the estimation of significant properties, such as flow, and chemical and mechanical resistances [6,7,8].…”

Section: Introductionmentioning

confidence: 99%

Advanced Laguerre Tessellation for the Reconstruction of Ceramic Foams and Prediction of Transport Properties

2019

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Ceramic foams are promising, highly porous materials, with a wide range of specific surface area and low fluid flow resistance, which are well-suited for filtering applications. They are comprised mainly of macrovoids that are interconnected with struts. A branch-shaped reconstruction algorithm is introduced in the present work to reconstruct various ceramic foams from electron microscopy images using the Laguerre tessellation method. Subsequently, the reconstructed samples are used for the numerical calculation of pore structure and transport properties, including specific surface area, tortuosity, effective diffusivity, and flow permeability. Following comparison with experimental data, this reconstruction method is shown to be more reliable than typical analytical expressions that are suggested in the literature for the aforementioned structural and transport properties. Extracting the equivalent pore radius of the reconstructed domains offers improved accuracy of the analytical expressions for the permeability estimation.

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“…A atividade antioxidante (AA) no café tem sido correlacionada tanto a presença de compostos fenólicos como ácido clorogênico, quanto a vários outros compostos nitrogenados como trigonelina e cafeína, e melanoidinas. No entanto, variações na composição dos grãos utilizados e processamento afetam essa característica (HIGDON;FREI, 2006;PARRAS et al, 2007;VIGNOLI;BASSOLI;BENASSI, 2011).…”

Section: Introductionunclassified

Atividade antioxidante e estimativa do teor de melanoidinas em cafés torrados comerciais

Almeida¹,

Benassi²

2011

Sem. Ci. Agr.

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Recebido para publicação 16/09/2010 Aprovado em 22/08/2011 O café contém vários componentes bioativos, em destaque os antioxidantes, cujo consumo tem sido correlacionado a redução da incidência de doenças crônicas e degenerativas. Dentre aproximadamente 100 espécies conhecidas do gênero Coffea as mais importantes economicamente no mercado internacional são Coffea arabica (café arábica) e Coffea canephora (café conilon), usualmente encontradas como blends em produtos comerciais. O café arábica apresenta melhor qualidade sensorial. Os compostos aos quais é atribuída a atividade antioxidante (AA) das bebidas de café incluem a classe de fenóis (destaque para o 5-ACQ) e cafeína, que têm sido mais usualmente estudados, e melanoidinas, produzidas no processo de torra, para as quais dados na literatura são escassos. Diferentes métodos são utilizados para caracterizar a capacidade antioxidante de alimentos, mas não existe uma metodologia eficiente e universal de medida. Nesse trabalho, cafés torrados e moídos nacionais comercializados com diferentes denominações (37 amostras), foram analisados quanto a concentração de melanoidinas, por espectrofotometria, e atividade antioxidante pelo método ABTS e de fenólicos totais (Folin-Ciocalteau). Todos os produtos avaliados apresentaram expressiva atividade antioxidante, mas observaram-se diferenças na estimativa do teor de melanoidinas, indicando processos de torra diferenciados. Considerando-se as diferentes categorias, cafés tipo Gourmet se destacaram pelos menores valores de AA, demonstrando que além do grau de torra a espécie de café empregada influenciava a funcionalidade do produto.

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Influência das condições de processamento cerâmico na resistência mecânica e na permeabilidade dos filtros de Al2O3-SiC

Cited by 6 publications

References 2 publications

LZSA glass ceramic foams prepared by replication process

LZSA glass ceramic foams prepared by replication process

Advanced Laguerre Tessellation for the Reconstruction of Ceramic Foams and Prediction of Transport Properties

Atividade antioxidante e estimativa do teor de melanoidinas em cafés torrados comerciais

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