Sintering behavior of porous SiC ceramics

Chi, Weiguang; Jiang, Dongliang; Huang, Zengqi; Shi, Tan

doi:10.1016/j.ceramint.2003.10.006

Cited by 88 publications

(57 citation statements)

References 11 publications

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“…Flexural strengths of ³10 MPa at ³50% porosity 41) and ³28 MPa at 44% porosity 42) were reported for reaction bonded porous ceramics and 17 MPa at ³61% porosity for sintered porous SiC ceramics. 43) The superior strength of the porous SiC ceramics with SiC fillers obtained in the present study is due to both the lack of macroscopic defects and the presence of a rigid strut with a well-developed grain structure.…”

Section: Resultsmentioning

confidence: 79%

Effect of filler addition on porosity and strength of polysiloxane-derived porous silicon carbide ceramics

Kumar

Eom

Kim

2011

J. Ceram. Soc. Japan

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Polycarbosilane (PCS) or silicon carbide (SiC) fillers were used as fillers in fabricating partially interconnected, open-cell porous SiC ceramics by carbothermal reduction of polysiloxane-derived SiOC and subsequent sintering process. The effects of filler type (PCS or SiC), filler content (050 mass %) and sintering temperature (18001950°C) on microstructure, porosity, and strength of the polysiloxane-derived porous SiC ceramics were investigated. The spherical pore morphology was retained with SiC filler addition, while irregular cells were dominant with PCS filler addition after sintering at low temperatures. The pore morphology became mostly irregular while the grain morphology changed from a mixture of small, equi-axed grains and large faceted grains to the large faceted grains with increase in sintering temperature from 1800 to 1950°C. Porosity decreased and strength increased with increase in sintering temperature irrespective of the filler source and content. PCS filler addition continuously increased the porosity and decreased the strength, whereas the porosity decreased and strength increased beyond 30 mass % SiC filler addition in the starting composition. Less strength was recorded for the ceramics prepared with PCS fillers. It was possible to adjust the porosity from 34 to 59% and flexural strength from 16 to 96 MPa by controlling the filler type, filler content, and sintering temperature.

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Section: Resultsmentioning

confidence: 79%

Effect of filler addition on porosity and strength of polysiloxane-derived porous silicon carbide ceramics

Kumar

Eom

Kim

2011

J. Ceram. Soc. Japan

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“…When hollow microspheres were used as templates, carbothermal reduction and subsequent sintering of carbon-filled polysiloxane rendered porous SiC ceramics with a flexural strength of 60 MPa and a compressive strength of 240 MPa at ∼40% porosity [100]. For comparison, flexural strengths of ∼10 MPa at ∼50% porosity [140] and ∼28 MPa at ∼44% porosity [141] were reported in reaction-bonded porous SiC ceramics and 17 MPa at ∼61% porosity in sintered porous SiC ceramics [142]. A compressive strength of ∼160 MPa was also reported at 40% porosity in porous SiC ceramics prepared using polymer microbeads as the sacrificial templates [143].…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Processing of polysiloxane-derived porous ceramics: a review

Kumar

Kim

2010

Science and Technology of Advanced Materials

112

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Because of the unique combination of their attractive properties, porous ceramics are considered as candidate materials for several engineering applications. The production of porous ceramics from polysiloxane precursors offers advantages in terms of simple processing methodology, low processing cost, and easy control over porosity and other properties of the resultant ceramics. Therefore, considerable research has been conducted to produce various Si(O)C-based ceramics from polysiloxane precursors by employing different processing strategies. The complete potential of these materials can only be achieved when properties are tailored for a specific application, whereas the control over these properties is highly dependent on the processing route. This review deals with processing strategies of polysiloxane-derived porous ceramics. The essential features of processing strategies-replica, sacrificial template, direct foaming and reaction techniques-are explained and the available literature reports are thoroughly reviewed with particular regard to the critical issues that affect pore characteristics. A short note on the cross-linking methods of polysiloxanes is also provided. The potential of each processing strategy on porosity and strength of the resultant SiC or SiOC ceramics is outlined.

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“…Este valor é próximo aos valores apresentados em bibliografias, conforme verificado na Tabela 2. O carbono apresenta expansão em temperaturas entre 650 e 1000 ºC [28], portanto, este valor verificado experimentalmente é significativo para auxiliar na etapa de formação da espuma.…”

Section: Resultsunclassified

“…Contudo, um pequeno, mas suficiente volume de gás fica retido na matriz vítrea no início do processo de densificação a aproximadamente 600 ºC, quando a viscosidade é adequada para a retenção deste, o que resulta em elevadas porosidades em temperaturas mais altas. Além disso, a quantidade de carbono presente na CA também auxilia na formação da estrutura porosa devido ao seu comportamento expansivo (formação de gases) entre 650 e 1000 ºC [28].…”

Section: Figura 1: Curvas De Retração Linear Do Vidro De Garrafa (Vg)unclassified

Produção e caracterização de espumas vitrocristalinas a partir de resíduos sólidos

et al. 2017

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RESUMONeste trabalho, foram produzidas espumas vitrocristalinas a partir de vidros de garrafas descartadas e casca de arroz (3 a 25% em massa), como agente porogênico. Diferentes composições foram preparadas de maneira a se obter materiais com porosidade controlada para aplicações, nas quais o isolamento térmico e a não-inflamabilidade são os principais requisitos técnicos. Os pós de cada matéria-prima (resíduos) foram homogeneizados e as misturas foram então prensadas uniaxialmente (20 MPa). Os compactos obtidos foram queimados em diferentes temperaturas (700 -950 o C) e tempos de patamares (30 -120 min). As matérias-primas e as espumas vitrocristalinas produzidas foram caracterizadas de acordo com suas propriedades químicas, físicas e estruturais. Os resultados mostraram que é possível produzir espumas vitrocristalinas a partir de composições otimizadas com 85% de vidros de garrafas e 15% de casca de arroz, queimadas a 900 o C por diferentes tempos. Tais espumas vitrocristalinas apresentaram porosidade variando entre 80 e 84% enquanto a condutividade térmica e a resistência mecânica à compressão variaram entre 0,068 e 0,082 W/m.K e entre 1,1 e 1,8 MPa, respectivamente. Palavras-chave: Espumas vitrocristalinas. Casca de arroz. Isolantes térmicos. Resíduos sólidos. ABSTRACTVitrocrystalline foams from discarded glass bottles and rice husk (3 to 25 wt%) as pore forming agent were produced in this work. Different compositions were prepared in order to obtain materials with controlled porosity in applications where thermal insulation and non-flammability are major requirements. Well-homogenized powders of the formulated compositions were uniaxially pressed (20 MPa) and the obtained compacts fired at different temperatures (700 -950°C) and holding times (30 -120 min). Raw materials and the obtained vitrocrystalline foams were characterized according to their chemical, physical and structural properties. The results showed that it is possible to produce vitrocrystalline foams from optimized compositions containing 85% glass bottle and 15% rice husk, fired at 900 o C for different holding times. These vitrocrystalline foams presented porosity varied from 80 to 84% while the thermal conductivity and compressive strength varied between 0.068 and 0.082 W/m.K and from 1.1 to 1.8 MPa, respectively.

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Sintering behavior of porous SiC ceramics

Cited by 88 publications

References 11 publications

Effect of filler addition on porosity and strength of polysiloxane-derived porous silicon carbide ceramics

Effect of filler addition on porosity and strength of polysiloxane-derived porous silicon carbide ceramics

Processing of polysiloxane-derived porous ceramics: a review

Produção e caracterização de espumas vitrocristalinas a partir de resíduos sólidos

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