• Journal of the Korean Ceramic Society
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• v.44 no.6 s.301
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• pp.325-330
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• 2007

High porous AlO(OH) gel is used in precursor of ceramic material, coating material and porous catalyst. For use of these, not only physiochemical control for particle morphology, pore characteristic and peptization but also studies of synthetic method for preparation of high porous AlO(OH) gel were required. In this study, high porous AlO(OH) gel was prepared through the aging and filtration process of aluminum hydroxides gel precipitated by the hydrolysis reaction of $Na_2CO_3$ solution and $Al_2(SO_4)_3$ and $Na_2SO_4$ mixed solution. In this process, optimum synthetic condition of AlO(OH) gel having excellent pore volume as studying the effect of hydrolysis pH on gel precipitates has been studied. Hydrolysis pH brought about numerous changes on crystal morphology, surface area, pore volume and pore size. Physiochemical properties of gel were investigated as using XRD, TEM, TG/DTA, FT-IR and $N_2$ BET method.

• Journal of the Korean Ceramic Society
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• v.49 no.3
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• pp.226-230
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• 2012

This paper presents a novel structure for a diesel particulate filter (DPF) with inclined gas paths, which was designed so that the gas paths offered a fluent flow of exhaust gases, and particulate matter (PM) was collected at pores formed in the body. The alumina porous filter was prepared by a conventional sintering process at $1200^{\circ}C$ for 2 h. Straight gas paths with $30^{\circ}$ of inclination from the gas flow direction were formed in the filter body. It is shown that this filter structure worked as a PM filter, in which 90.2% of soot filtration efficiency and 59.6 mbar of pressure drop were achieved.

• Journal of the Korean Ceramic Society
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• v.30 no.3
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• pp.189-198
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• 1993

A new pressurized sol-gel coating technique forming membrane layers inside pores of the porous support by the simple operation has been developed. Crack-free and reproducible nanoparticulate silica membranes supported on the porous $\alpha$-alumina tube are synthesized by pressurized coating at 600kPa for 2hr. The pore radius and N2 gas permiability at the room temperature of silica membrane layers are 8$\AA$ and 7.0$\times$10-7mol/$m^2$.s.Pa, respectively. The mechanism of N2 gas transfer through synthesized membrane layers is the perfect Knudeen flow, and the thermal stability of the silica composite membranes is excellent upto 40$0^{\circ}C$.

• Proceedings of the Membrane Society of Korea Conference
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• 2002.05a
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• pp.35-41
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• 2002

Dense oxygen ionic conducting materials can be used for oxygen separation membranes at high temperatures. However, they show relatively low permeation flux because of their large resistances. To reduce resistances and improve the oxygen permeation flux, thin dense yttria-stabilized-zirconia (YSZ)/Pd composite dual-phase membranes were fabricated by a new approach that combines the reservoir method and chemical vapor deposition (CVD). A thin porous YSZ layer was coated on a porous alumina support by dip-coating the YSZ suspension. A continuous Pd phase was formed inside pores of the YSZ layer by the reservoir method. The residual pores of the YSZ/Pd layer were plugged with yttria/zirconia by CVD to ensure the gas tightness of the membranes. The oxygen permeation fluxes through these composite membrane were 2.0$\times$10$^{-8}$ mol/cm$^2$.s and 4.8$\times$10$^{-8}$ mol/cm$^2$.s at 105$0^{\circ}C$ when air and oxygen were used as the permeate gases, respectively. These oxygen permeation values are about 1 order of magnitude higher than those of pure YSZ membranes prepared under similar conditions.

• 연구논문집
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• s.33
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• pp.147-155
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• 2003

In order to fabricate porous materials having an anisotropic thermal conductivity by aligning plate-shaped pores structure, alumina powder (AM-21, mean particle size $4\mum$) and flake crystalline graphite was used. The aligned pore structure was realized using multi-pressing process. Degree of pore orientation increased with the number of pressing and thermal conductivity, parallel to the pressing direction, decreased with the number of pressing. Thermal conductivity decreased significantly to the addition of 30vol% crystalline graphite, however, in the case of 60vol%, thermal conductivity did not decrease significantly due to the breakage of crystalline graphite. An anisotropy of the thermal conductivity increased with the content of crystalline graphite up to 30vol%. Graded pore structure was fabricated by controlling the content and size of crystalline graphite, which provides, possibly, the enhancement in mechanical strength and thermal insulation properties of the insulating bricks.

• Bulletin of the Korean Chemical Society
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• v.10 no.3
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• pp.292-297
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• 1989

In this work we have experimentally observed the physisorption isotherms for nitrogen, TMS, cyclohexane, benzene, and n-hexane adsorbed on flat aluminum foil surface and have analyzed them theoretically on the basis of the theory proposed by Chang et al. The results show that the theory by Chang et al. can provide a useful means to describe the physisorption of gases on uniform flat solid surface which is essentially important for analysis of the pore volume distribution in porous solid surface. We have also discussed the application of the results obtained in this work to the analysis of pore volume distribution in porous alumina we reported previously.

• Bulletin of the Korean Chemical Society
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• v.13 no.3
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• pp.332-334
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• 1992

An accurate method of density measurement is proposed. The method makes use of a gravimetric adsorption apparatus and is quite suitable for powdery and porous solid samples. The sample volume is determined by measuring its buoyancy with microbalance and the mass is measured in vacuum in the absence of buoyancy effect. Densities of inorganic compounds, such as alumina and perovskite, and some organic compounds are determined with the proposed method, and the results are compared with the values either determined with conventional methods or obtained from literatures.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.12a
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• pp.175-175
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• 2003

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.199.1-199.1
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• 2007

• Proceedings of the Korean Magnestics Society Conference
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• 2009.12a
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• pp.101-102
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• 2009