Preparation of macroporous alumina ceramics using wheat particles as gelling and pore forming agent

Prabhakaran, K.; Melkeri, Anand; Gokhale, N.M.; Sharma, S. C.

doi:10.1016/j.ceramint.2005.07.020

Cited by 81 publications

(44 citation statements)

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“…Many alternative gelling systems for the gel-casting of foams based on low-toxicity monomers were demonstrated by Ortega et al [5] and a low toxic epoxy resin system was demonstrated by Mao et al [6]. Gel-casting techniques utilizing environmentally friendly biopolymers as gelformers in manufacturing of ceramic foams were intensively studied: different biopolymers such as gelatin [6], proteins (ovalbumine and bovine serum albumin) [7][8][9][10], sucrose [11], agar [12], starch [13], and wheat particles [14] have recently been applied as non-toxic components for the fabrication of gel-cast ceramic foams.…”

Section: Introductionmentioning

confidence: 98%

Microstructural, mechanical and thermal characterization of alumina gel-cast foams manufactured with the use of agarose as gelling agent

et al. 2015

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Alumina gel-cast foams manufactured by using agarose as gelling agent were examined in terms of microstructural, mechanical and thermal properties. The microstructural SEM measurements of alumina foams were compared with X-ray micro tomography investigations also on the pore network. Young's modulus of alumina foams was determined by impulse excitation and ultrasonic sound velocity measurements. These two independent techniques showed similar results. Gibson and Ashby's model of completely open-cell and closed-cell foams was compared with experimental data from compression tests. The thermal conductivity measurements using laser-flash analysis were correlated with the pore network in the alumina foam structure.

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Section: Introductionmentioning

confidence: 98%

Microstructural, mechanical and thermal characterization of alumina gel-cast foams manufactured with the use of agarose as gelling agent

et al. 2015

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“…Generally used poreformers are organic and inorganic materials, which include inorganic salts such as calcium chloride, ammonium chloride, polystyrene, PMMA, Fe 2 O 3 urea, starch, wheat, etc. [1][2][3][4][5][6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Processing of silica bonded porous SiC preform for metallic composites

et al. 2015

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Porous SiC ceramics were successfully fabricated by silica bonding of SiC compacts and porogen burnout technique. Silica coating on SiC particle was carried out using TEOS hydrolysis and crystallizes during the sintering process at 1200°C, which forms a well-developed neck growth between the SiC particles. Different volume fractions of sodium chloride porogen were used to obtain varied porosity content in porous SiC ceramics from 36 to 62.47 % leading to wide-ranging compressive strength from 8.11 to 0.69 MPa. Interconnected bimodal pores were created throughout the sample due to the burnt out of salt and stacking of SiC particles. The pore size distribution of porous SiC measured using mercury intrusion porosimetry shows that average pore size due to the salt particle is around 74-110 lm and stacking of SiC particle result 4-10 lm. Direct squeeze infiltration method is successfully adopted for infiltration of 6061 aluminium molten alloy into SiC preforms with the controlled process parameters of initial preform temperature, liquid metal superheating, squeezed pressure and its rate of application and die temperature. Microstructures have shown complete infiltration of Al alloy into the pores of the SiC preform forming Al composite with good interfacial bonding aided by the presence of MgAl 2 O 4 spinel. The silica coating on SiC surface have a multifunctional role of acting as a binder for the porous preform, enhances the wettability of SiC particle with molten metal during infiltration and prevention of deleterious Al 4 C 3 interfacial reaction product.

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“…Devido às suas inúmeras aplicações, estudos têm sido desenvolvidos para incrementar as técnicas de processamento dessas cerâmicas porosas, tais como: inclusão de fase orgânica [10,11]; método da réplica da esponja polimérica [12,13]; método do gelcasting associado à aeração [14,15]; entre outras [16,17]. Dentre os métodos, o gelcasting promove a formação de um reticulado tridimensional, a partir da reação de copolimerização que, quando associado à aeração, possibilita a obtenção de uma estrutura com paredes densas, sem defeitos e ao mesmo tempo com elevada porosidade [14,15,18].…”

Section: Introductionunclassified

Análise comparativa entre diferentes ensaios porosimétricos em alumina macroporosa

et al. 2018

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RESUMOCerâmicas macroporosas de alumina (Al 2 O 3 ) são estudadas devido às suas diversas aplicações como biomateriais para implantes ósseos, ânodos para célula combustível de óxido sólido, entre outras. Nesse sentido, a distribuição, tamanho e interconexão dos poros podem determinar características físicas e mecânicas dessas cerâmicas. Assim sendo, o objetivo desse trabalho foi analisar e comparar diferentes métodos de caracterizações porosimétricas em amostras macroporosas de Al 2 O 3 . Para isso, os métodos analisados foram intrusão de mercúrio (PIM), método de Arquimedes (MA), análise de micrografias (AM) e ressonância magnética nuclear com pulsos de radiofrequência Carr-Purcell-Meiboom-Gill ( 1 H-RMN -CPMG). Amostras macroporosas de Al 2 O 3 foram obtidas pelo método de gelcasting modificado pela incorporação de esferas de polietileno, em diferentes quantidades. Os resultados foram tratados matematicamente e correlacionados pelo coeficiente de Pearson. As principais vantagens do MA foram a rapidez e a simplicidade na obtenção da porosidade aparente. No entanto, curvas de distribuição de tamanho de poros não são obtidas por esse método. As distribuições dos tamanhos dos poros obtidas por 1 H-RMN -CPMG foram semelhantes às do PIM. Essa semelhança é evidenciada pelo alto coeficiente de Pearson entre os dois métodos (r >0,962). As análises da forma e homogeneidade dos poros, bem como a porosidade aparente, foram melhores determinadas por AM. Porém, quando comparada com o método PIM, divergências quanto à distribuição de tamanho de poros foram observadas. Isso é evidenciado pelo baixo coeficiente de Pearson (r <0,048). Pode-se assim concluir que métodos não convencionais na determinação da porosidade ( 1 H-RMN -CPMG e AM) podem ser utilizados alternativamente aos convencionais (PIM e MA) na caracterização de materiais macroporosos.Palavras-chave: porosimetria, ressonância magnética, intrusão de mercúrio, análise de micrografias. ABSTRACTMacroporous ceramics of Al 2 O 3 are being studied due their diverse applications (biomaterials, anode for solid oxide fuel cells, etc.). The pore distribution, size and interconnection are important parameters that can determine physical and mechanical characteristics of these materials. The aim of this study was analyze and compare different methods of porosimetry. For this, we used the mercury intrusion porosimetry (PIM), Archimedes method (MA), micrographic analysis (AM) and nuclear magnetic resonance with CPMG radiofrequency pulses ( 1 H-RMN -CPMG). Samples of macroporous Al 2 O 3 were obtained by the gelcasting method modified by incorporation of polyethylene spheres at different amounts. The results of these porosimetry methods were treated mathematically, and then the Pearson correlation between the pore size distributions were analyzed. The main advantage of the MA was the simplicity to obtain the apparent porosity, although this method did not provide the pore size distribution. The pore size distribution obtained by 1 H-RMN -CPMG was similar to those obtained by PIM. T...

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Preparation of macroporous alumina ceramics using wheat particles as gelling and pore forming agent

Cited by 81 publications

References 20 publications

Microstructural, mechanical and thermal characterization of alumina gel-cast foams manufactured with the use of agarose as gelling agent

Microstructural, mechanical and thermal characterization of alumina gel-cast foams manufactured with the use of agarose as gelling agent

Processing of silica bonded porous SiC preform for metallic composites

Análise comparativa entre diferentes ensaios porosimétricos em alumina macroporosa

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