Microstructure and elastic properties of highly porous mullite ceramics prepared with wheat flour

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F60461373%3A22310%2F16%3A43902681" target="_blank" >RIV/60461373:22310/16:43902681 - isvavai.cz</a>

Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Microstructure and elastic properties of highly porous mullite ceramics prepared with wheat flour

Popis výsledku v původním jazyce

Porous mullite-based foams prepared by direct foaming with wheat flour and partial sintering at 1600 oC have been characterized via optical and electron microscopy, stereology- based image analysis, mercury porosimetry and impulse excitation. By varying the time of homogenization in a shaker from 0.1 to 10 h the porosity of the mullite foams could be varied in the range 49-88 % and the mean foam cell size in the range 105-320 ?m. Microscopic investigation and mercury porosimetry confirmed that the pore space is essentially open (interconnected) and revealed the hierarchical microstructure of the materials, consisting of large foam cells, intermediate convex pores from wheat starch burnout and small concave pores between the partially sintered ceramic particles, on all levels interconneted by cell windows or throats that are significantly smaller than the foam cells and pore cavities. Elastic properties have been determined with specimens in the form of thin circular disks, using the resonant frequencies of flexural and anti-flexural vibrations. It has been found that for samples with porosities of 78 % and higher the Young's modulus and shear modulus are very close to the power-law prediction (Gibson-Ashby relation for open-cell foams), whereas for smaller porosities the values are much lower and for porosities of 48 % even lower than our exponential relation, which indicates the dominating effect of concave pores (due to partial sintering of convex particles). Poisson ratios are close to the value 0.2 and reasonably well predicted by the linear approximation.

Název v anglickém jazyce

Microstructure and elastic properties of highly porous mullite ceramics prepared with wheat flour

Popis výsledku anglicky

Porous mullite-based foams prepared by direct foaming with wheat flour and partial sintering at 1600 oC have been characterized via optical and electron microscopy, stereology- based image analysis, mercury porosimetry and impulse excitation. By varying the time of homogenization in a shaker from 0.1 to 10 h the porosity of the mullite foams could be varied in the range 49-88 % and the mean foam cell size in the range 105-320 ?m. Microscopic investigation and mercury porosimetry confirmed that the pore space is essentially open (interconnected) and revealed the hierarchical microstructure of the materials, consisting of large foam cells, intermediate convex pores from wheat starch burnout and small concave pores between the partially sintered ceramic particles, on all levels interconneted by cell windows or throats that are significantly smaller than the foam cells and pore cavities. Elastic properties have been determined with specimens in the form of thin circular disks, using the resonant frequencies of flexural and anti-flexural vibrations. It has been found that for samples with porosities of 78 % and higher the Young's modulus and shear modulus are very close to the power-law prediction (Gibson-Ashby relation for open-cell foams), whereas for smaller porosities the values are much lower and for porosities of 48 % even lower than our exponential relation, which indicates the dominating effect of concave pores (due to partial sintering of convex particles). Poisson ratios are close to the value 0.2 and reasonably well predicted by the linear approximation.

Druh

D - Stať ve sborníku

CEP obor

JH - Keramika, žáruvzdorné materiály a skla

OECD FORD obor

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Projekt

<a href="/cs/project/GA15-18513S" target="_blank" >GA15-18513S: Příprava a charakterizace oxidové a silikátové keramiky s řízenou mikrostrukturou a modelování souvislostí mezi mikrostrukturou a vlastnostmi</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2016

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

11th International Symposium on Ceramic Materials and Components for Energy and Environmental Applications

ISBN

978-1-119-23458-6

ISSN

1042-1122

e-ISSN

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Počet stran výsledku

12

Strana od-do

83-94

Název nakladatele

American Ceramic Society (ACerS)

Místo vydání

Westerville, Ohio

Místo konání akce

Vancouver / Canada

Datum konání akce

14. 6. 2015

Typ akce podle státní příslušnosti

WRD - Celosvětová akce

Kód UT WoS článku

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