Combined effects of SiO2 ratio and purity on physical properties and microstructure of in situ alumina-mullite ceramic
Autor(a) principal: | |
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Data de Publicação: | 2021 |
Outros Autores: | , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Institucional da UNESP |
Texto Completo: | http://dx.doi.org/10.1111/ijac.13733 http://hdl.handle.net/11449/205986 |
Resumo: | The in situ formation of mullite (Al6Si4O13) is a complex process based on solid-state reactions strongly affected by the characteristics of Al2O3 and SiO2 sources. This study investigated the combined effects of variable SiO2/Al2O3 ratios and the presence of low-melting-point impurities on the physical properties and microstructure of in situ alumina-mullite ceramics. Two grades of synthetic amorphous silica, known as microsilica, of similar physical properties and significant differences in the content of alkali-based impurities (0.8 and 3.6 wt%), were combined with thin calcined alumina particles in different proportions (from silica-free up to stoichiometric mullite), pressed and sintered. The samples were tested for total porosity, flexural strength, and pore size distribution, and their crystalline phases and microstructures formed were investigated. Small amounts of both microsilica grades (up to 8.9 wt%) hindered the densification of the alumina-mullite matrix and favored grain growth events, increasing porosity and reducing strength. For samples containing higher microsilica loads (16.4–28.2 wt%), the impurities content significantly affected the amount of liquid phases formed. Such impurities altered the ratio and shape of the pores and the total amount of mullite after sintering. Therefore, different microstructures and levels of flexural strength and total porosity were observed. |
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Combined effects of SiO2 ratio and purity on physical properties and microstructure of in situ alumina-mullite ceramiccalcined aluminaimpuritiesin situ reactionleaching treatmentmicrosilicamulliteThe in situ formation of mullite (Al6Si4O13) is a complex process based on solid-state reactions strongly affected by the characteristics of Al2O3 and SiO2 sources. This study investigated the combined effects of variable SiO2/Al2O3 ratios and the presence of low-melting-point impurities on the physical properties and microstructure of in situ alumina-mullite ceramics. Two grades of synthetic amorphous silica, known as microsilica, of similar physical properties and significant differences in the content of alkali-based impurities (0.8 and 3.6 wt%), were combined with thin calcined alumina particles in different proportions (from silica-free up to stoichiometric mullite), pressed and sintered. The samples were tested for total porosity, flexural strength, and pore size distribution, and their crystalline phases and microstructures formed were investigated. Small amounts of both microsilica grades (up to 8.9 wt%) hindered the densification of the alumina-mullite matrix and favored grain growth events, increasing porosity and reducing strength. For samples containing higher microsilica loads (16.4–28.2 wt%), the impurities content significantly affected the amount of liquid phases formed. Such impurities altered the ratio and shape of the pores and the total amount of mullite after sintering. Therefore, different microstructures and levels of flexural strength and total porosity were observed.Materials Engineering Department São Carlos School of Engineering University of São PauloDepartment of Dental Materials and Prosthodontics School of Dentistry São Paulo State University (UNESP)International Iberian Nanotechnology Laboratory (INL)Department of Dental Materials and Prosthodontics School of Dentistry São Paulo State University (UNESP)Universidade de São Paulo (USP)Universidade Estadual Paulista (Unesp)International Iberian Nanotechnology Laboratory (INL)Salomão, RafaelFernandes, Leandro [UNESP]Spera, Natalia C. M.2021-06-25T10:24:44Z2021-06-25T10:24:44Z2021-01-01info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articlehttp://dx.doi.org/10.1111/ijac.13733International Journal of Applied Ceramic Technology.1744-74021546-542Xhttp://hdl.handle.net/11449/20598610.1111/ijac.137332-s2.0-85101870388Scopusreponame:Repositório Institucional da UNESPinstname:Universidade Estadual Paulista (UNESP)instacron:UNESPengInternational Journal of Applied Ceramic Technologyinfo:eu-repo/semantics/openAccess2021-10-22T20:28:31Zoai:repositorio.unesp.br:11449/205986Repositório InstitucionalPUBhttp://repositorio.unesp.br/oai/requestopendoar:29462021-10-22T20:28:31Repositório Institucional da UNESP - Universidade Estadual Paulista (UNESP)false |
dc.title.none.fl_str_mv |
Combined effects of SiO2 ratio and purity on physical properties and microstructure of in situ alumina-mullite ceramic |
title |
Combined effects of SiO2 ratio and purity on physical properties and microstructure of in situ alumina-mullite ceramic |
spellingShingle |
Combined effects of SiO2 ratio and purity on physical properties and microstructure of in situ alumina-mullite ceramic Salomão, Rafael calcined alumina impurities in situ reaction leaching treatment microsilica mullite |
title_short |
Combined effects of SiO2 ratio and purity on physical properties and microstructure of in situ alumina-mullite ceramic |
title_full |
Combined effects of SiO2 ratio and purity on physical properties and microstructure of in situ alumina-mullite ceramic |
title_fullStr |
Combined effects of SiO2 ratio and purity on physical properties and microstructure of in situ alumina-mullite ceramic |
title_full_unstemmed |
Combined effects of SiO2 ratio and purity on physical properties and microstructure of in situ alumina-mullite ceramic |
title_sort |
Combined effects of SiO2 ratio and purity on physical properties and microstructure of in situ alumina-mullite ceramic |
author |
Salomão, Rafael |
author_facet |
Salomão, Rafael Fernandes, Leandro [UNESP] Spera, Natalia C. M. |
author_role |
author |
author2 |
Fernandes, Leandro [UNESP] Spera, Natalia C. M. |
author2_role |
author author |
dc.contributor.none.fl_str_mv |
Universidade de São Paulo (USP) Universidade Estadual Paulista (Unesp) International Iberian Nanotechnology Laboratory (INL) |
dc.contributor.author.fl_str_mv |
Salomão, Rafael Fernandes, Leandro [UNESP] Spera, Natalia C. M. |
dc.subject.por.fl_str_mv |
calcined alumina impurities in situ reaction leaching treatment microsilica mullite |
topic |
calcined alumina impurities in situ reaction leaching treatment microsilica mullite |
description |
The in situ formation of mullite (Al6Si4O13) is a complex process based on solid-state reactions strongly affected by the characteristics of Al2O3 and SiO2 sources. This study investigated the combined effects of variable SiO2/Al2O3 ratios and the presence of low-melting-point impurities on the physical properties and microstructure of in situ alumina-mullite ceramics. Two grades of synthetic amorphous silica, known as microsilica, of similar physical properties and significant differences in the content of alkali-based impurities (0.8 and 3.6 wt%), were combined with thin calcined alumina particles in different proportions (from silica-free up to stoichiometric mullite), pressed and sintered. The samples were tested for total porosity, flexural strength, and pore size distribution, and their crystalline phases and microstructures formed were investigated. Small amounts of both microsilica grades (up to 8.9 wt%) hindered the densification of the alumina-mullite matrix and favored grain growth events, increasing porosity and reducing strength. For samples containing higher microsilica loads (16.4–28.2 wt%), the impurities content significantly affected the amount of liquid phases formed. Such impurities altered the ratio and shape of the pores and the total amount of mullite after sintering. Therefore, different microstructures and levels of flexural strength and total porosity were observed. |
publishDate |
2021 |
dc.date.none.fl_str_mv |
2021-06-25T10:24:44Z 2021-06-25T10:24:44Z 2021-01-01 |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://dx.doi.org/10.1111/ijac.13733 International Journal of Applied Ceramic Technology. 1744-7402 1546-542X http://hdl.handle.net/11449/205986 10.1111/ijac.13733 2-s2.0-85101870388 |
url |
http://dx.doi.org/10.1111/ijac.13733 http://hdl.handle.net/11449/205986 |
identifier_str_mv |
International Journal of Applied Ceramic Technology. 1744-7402 1546-542X 10.1111/ijac.13733 2-s2.0-85101870388 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
International Journal of Applied Ceramic Technology |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.source.none.fl_str_mv |
Scopus reponame:Repositório Institucional da UNESP instname:Universidade Estadual Paulista (UNESP) instacron:UNESP |
instname_str |
Universidade Estadual Paulista (UNESP) |
instacron_str |
UNESP |
institution |
UNESP |
reponame_str |
Repositório Institucional da UNESP |
collection |
Repositório Institucional da UNESP |
repository.name.fl_str_mv |
Repositório Institucional da UNESP - Universidade Estadual Paulista (UNESP) |
repository.mail.fl_str_mv |
|
_version_ |
1799965604169383936 |