• Journal of the Korean Ceramic Society
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• v.49 no.5
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• pp.427-431
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• 2012

The $TiO_2$ foam synthesized using freeze-casting is a promising photocatalyst and photovoltaic electrode for a variety of energy applications, because the freeze-casting technique is easy to use, cheap, and suitable for mass-production. Despite its several advantages, little scientific information is available on the processing and morphology of the $TiO_2$ foams processed by freeze-casting. In particular, no systematic study has been performed on the microstructural evolution and morphological change of the rutile-phase $TiO_2$ foams during sintering. Therefore, in the present study, several $TiO_2$ foam samples were produced using the freeze-casting technique, which were then sintered at a relatively high temperature of $1200^{\circ}C$ for 1, 2, and 4 h to compare the morphological changes in the microstructure and to understand the effects of processing parameters of the rutile-phase $TiO_2$ foams. The foam ligament size increased near linearly with increasing sintering time whereas the average pore size decreased only slightly with increasing sintering time, with changes in particle morphology from sphere to rod and complete phase transformation from anatase to rutile.

• International Journal of Advanced Culture Technology
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• v.3 no.1
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• pp.21-30
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• 2015

Ceramic foams are prepared as positive images corresponding to a plastic foam structure which exhibits high porosities (85-90%). This structure makes the ceramic foams attractive as a catalyst in a dry reforming process, because it could reduce a high pressure drop problem. This problem causes low mass and heat transfers in the process. Furthermore, the reactants would shortly contact to catalyst surface, thus low conversion could occur. Therefore, this research addressed the preparation of dry reforming catalysts using a sol-gel catalyst preparation via a polymeric sponge method. The specific objectives of this work are to investigate the effects of polymer foam structure (such as porosity, pore sizes, and cell characteristics) on a catalyst performance and to observe the influences of catalyst preparation parameters to yield a replica of the original structure of polymeric foam. To accomplish these objectives industrial waste foams, polyurethane (PU) and polyvinyl alcohol (PVA) foams, were used as a polymeric template. Results indicated that the porosity of the polyurethane and polyvinyl alcohol foams were about 99% and 97%. Their average cell sizes were approximate 200 and 50 micrometres, respectively. The cell characteristics of polymer foams exhibited the character of a high permeability material that can be able to dip with ceramic slurry, which was synthesized with various viscosities, during a catalyst preparation step. Next, morphology of ceramic foams was explored using scanning electron microscopy (SEM), and catalyst properties, such as; temperature profile of catalyst reduction, metal dispersion, and surface area, were also characterized by $H_2-TPR$ and $H_2-TPD$ techniques, and BET, respectively. From the results, it was found that metal-particle dispersion was relatively high about 5.89%, whereas the surface area of ceramic foam catalysts was $64.52m^2/g$. Finally, the catalytic behaviour toward hydrogen production through the dry reforming of methane using a fixed-bed reactor was evaluated under certain operating conditions. The approaches from this research provide a direction for further improvement of marketable environmental friendly catalyst production.

• Journal of the Korean Ceramic Society
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• v.41 no.7
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• pp.555-559
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• 2004

Ceramic foams were prepared by a self-blowing process of a polysiloxane with A1$_2$O$_3$ as a filler. The release of water and ethanol vapor during the condensation reaction of the polymer triggered the pores in the polymer melt. The size. interconnectivity and shape of the pores in the ceramic foams were strongly dependent on the viscosity of the polymer melt, which could be varied by the content and size oi the filler. When the content of the filler inceased and the size of the filler decreased. the size of the pores were decreased and the thickness between the pores were increased. In the addition, the viscosity of polymer melt increased by the pretreatment at 130$^{\circ}C$ for Ire intermolecular cross linking thereby stabilizing the foam structure. The density and compressive strength of the ceramic foams were affected by the heating rate during the blowing process.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.156.1-156
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• 2003

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.68.1-68
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• 2003

• Journal of the Korean Ceramic Society
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• v.50 no.2
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• pp.93-102
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• 2013

Macro porous ceramics possessing controlled microstructures and chemical compositions have increasingly proven useful in the industrial sphere. Their sintered structures have found application in both established and emerging, areas such as thermal insulation in buildings, filtration of liquids and molten materials, refractory insulation, bone scaffolds and tissue engineering. Stable ceramic foams can be formed by wet chemical methods using inorganic particles(e.g., $Al_2O_3$ or $SiO_2$). The wet foams are dried and sintered with improved porosity and mechanical properties. This review examines the different techniques used to prepare porous ceramics from ceramic foams, focusing on the explanation of this versatile method of direct foaming from the past to the present. Comparisons of the processes and the processing parameters are explained with the produced microstructures.

• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.463-466
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• 2011

Wet foams formed through direct foaming were stabilized using various concentrations of amiphiphilic particles that could control pore size and porosity. These porous materials showed moderate strength upon compression with high porosity. Bubble size and wet foam stability were tailored by amphiphile concentration, particle concentration, contact angle, and pH of the suspension to obtain crack-free porous solid after sintering. Closed and open pores were obtained with sizes of 30~300 ${\mu}m$ and porosities of over 80%.

• Proceedings of the Korean Ceranic Society Conference
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• 2004.04b
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• pp.43.3-43.3
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• 2004

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.14.2-14
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• 2003

• Journal of the Korean Ceramic Society
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• v.49 no.3
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• pp.236-240
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• 2012

The reticulated carbon foam have been used for their excellent properties in terms of thermal management which is getting important in industrial field currently. In this study, we measure the mechanical properties of the reticulated carbon foam which is heat-treated at various temperature from the prepared low-density phenol foam. Simultaneously, we observe microstructures with high resolution transmission microscope and measure the residual oxygen content of carbon foams to figure out the relationship between the apparent change of properties such as weight loss and linear shrinkage during heat treatment. In conclusion, the carbon foam heat-treated at $1400^{\circ}C$ shows the highest strength, and the mechanical behavior is believed to be strongly related to the creation of nano-size graphite crystals from the amorphous carbon during heat treatment. On the other hand, it is turned out that the weight loss occurred at the temperature under $1400^{\circ}C$ comes from the elimination of oxygen in the form of $CO_2$ or CO, but no evidence is found on weight loss mechanism at the temperature above $1400^{\circ}C$.