• 한국환경과학회지
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• 제7권5호
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• pp.669-677
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• 1998

A porous $\alpha$-alumina tube of 2.5 mm O.D. and 1.9 mm I.D. was used as the support of an inorganic membrane. Macropores of the tube, about 150 nm in size, were plugged with silica formed by thermal decomposition of tetraethylorthosilicate at $600^{\circ}C$. The forced cross-flow CVD method that reactant was evacuated through the porous wall of the support was very effective in plugging macropores. The H$_2$ permeance of the prepared membrane was of the order of $10^{-8}/ molㆍs^{-1}/ㆍm^{-2}/. Pa{-1}$/, while the $N_2$ permeance was below $10^{-11}/ molㆍs^{-1}/ㆍm^{-2}/ㆍPa^{-1}$/ at $600^{\circ}C$. This was comparable to that of silica-modified Vycor glass whose size was 4 nm.

• 멤브레인
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• 제11권3호
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• pp.124-132
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• 2001

고온에서 수소 분리 회수를 목적으로 silica/alumina 복합 막을 합성하였다. 막의 선택 투과 성능을 향상시키기 위해, sol-gel법에 의한 silica 및 alumina층을 중간층으로 도입하고, 그 위에 강제유동 CVD법에 의한 silica를 합성하였다. Sol-gel법에 의해 ${\alpha}$-alumina tube에 합성한 ${\gamma}$-alumina 및 silica 막은 Knudsen 확산 영역의 많은 mesopore를 포함하고 있어서 수소 선택 분리 막으로는 적합하지 못했다. 하지만, sol-gel법에 의해 합성한 silica/${\gamma}$-alumina층에 강제유동 CVD법으로 silica를 합성한 결과, 질소 투과 영역의 세공이 완전히 제거되어, 높은 수소 선택성을 가지는 복합 막이 형성되었다. 그 막은 온도에 따라 수소 투과 속도가 증가하여 $450^{\circ}C$에서 $5.57{\times}10^{-8}molm^2s^LPa^1$의 수소 투과 속도와, 9.52 kJ/mol의 활성화 에너지를 나타냈다. 분자체 효과에 의해 질소 투과가 완전히 배제되고, 수소만 선택적으로 투과되는 silica/alumina 복합막이 성공적으로 합성된다.

• 멤브레인
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• 제25권1호
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• pp.15-26
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• 2015

본 연구에서는 기공의 크기가 큰 다공성 지지체를 $3{\sim}4{\mu}m$, 150 nm의 크기를 갖는 ${\alpha}$-알루미나 입자를 물과 실리카-지르코니아 용액에 각각 분산시키는 방법으로 표면 개질을 하였다. $3{\sim}4{\mu}m$ 크기의 알루미나 입자가 분산된 용액을 이용하여 금속 지지체 및 알루미나 지지체에 코팅하였을 때, 코팅횟수가 증가할수록 지지체의 표면의 큰 기공이 감소하였고, 여기에 150 nm 크기의 알루미나 입자가 분산된 용액으로 추가 코팅을 하면 작은 크기의 알루미나 입자가 기공 사이사이에 들어가면서 지지체를 좀 더 매끄럽게 개질하는 역할을 하는 것을 확인하였다. 특히 실리카-지르코니아 용액을 분산매로 하여 표면 개질을 한 경우, 알루미나 입자가 실리카-지르코니아 층에 촘촘하게 박힌 모양으로 고정이 되어 지지체 개질에 효과적임을 확인하였다. 이러한 방법으로 제조된 실리카-지르코니아 분리막의 기체투과도는 상온에서 각각 $1.8-8.4{\times}10^{-4}mol{\cdot}m^{-2}{\cdot}s^{-1}{\cdot}Pa^{-1}$, $3.3-5.0{\times}10^{-5}mol{\cdot}m^{-2}{\cdot}s^{-1}{\cdot}Pa^{-1}$이며 수소/질소 선택도는 Knudsen 분포를 보였다. 표면 개질된 지지체에 다양한 분리층을 형성하는 방법으로 무기 분리막 응용에 이용할 수 있을 것으로 예상된다.

• 한국세라믹학회지
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• 제51권6호
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• pp.544-548
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• 2014

Aluminum nitride was synthesized using a carbothermal method from mesoporous alumina having a high surface area (> $1,000m^2/g$) as an aluminum source and CNTs (carbon nano tubes) as a carbon source. In this case the mesoporous alumina was used as the starting material instead of ${\alpha}-Al_2O_3$ with the expectation that the mesopores in mesoporous alumina act as channels for N2 gas and elimination of CO generated as by-product. It is also expected that the synthetic temperature should be lower compared to the use of ${\alpha}-Al_2O_3$ as a starting material due to its high surface area. The crystallinity of the produced aluminum nitride was studied by XRD and FT-IR, and the microstructure was investigated by FE-SEM. Also the purity of the aluminum nitride was analyzed through N/O determinator and ICP analysis.

• Macromolecular Research
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• 제15권6호
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• pp.565-574
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• 2007

In this study, five representative, commercially available polymers, Ultem 1000 polyetherimide, Kapton polyimide, phenolic resin, polyacrylonitrile and cellulose acetate, were used to prepare pyrolyzed polymer membranes coated on a porous {\alpha}-alumina$ tube via inert pyrolysis for gas separation. Pyrolysis conditions (i.e., final temperature and thermal dwell time) of each polymer were determined using a thermogravimetric method coupled with real-time mass spectroscopy. The surface area and pore size distribution of the pyrolyzed materials derived from the polymers were estimated from the nitrogen adsorption/desorption isotherms. Pyrolyzed membranes from polymer precursors exhibited type I sorption behavior except cellulose acetate (type IV). The gas permeation of the carbon/{\alpha}-alumina$ tubular membranes was characterized using four gases: helium, carbon dioxide, oxygen and nitrogen. The polyetherimide, polyimide, and phenolic resin pyrolyzed polymer membranes showed typical molecular sieving gas permeation behavior, while membranes from polyacrylonitrile and cellulose acetate exhibited intermediate behavior between Knudsen diffusion and molecular sieving. Pyrolyzed membranes with molecular sieving behavior (e.g., polyetherimide, polyimide, and phenolic resin) had a $CO_2/N_2$ selectivity of greater than 15; however, the membranes from polyacrylonitrile and cellulose acetate with intermediate gas transport behavior had a selectivity slightly greater than unity due to their large pore size.

• 한국환경과학회지
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• 제9권4호
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• pp.311-318
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• 2000

To improve $CO_2$pemselectivity, a modified silica membrane was prepared by chemical vapor deposition with tetraethoxysilane(TEOS)-ethanol-water, and TEOS-ethanol-water-HCI solution at 300-$600^{\circ}C$. The silica was effectively deposited in the mesopores of a ${\gamma}$-alumina film coated on a porous $\alpha$-alumina tube by evacuating the reactants through the porous wall. In this membrane, $CO_2$interacts, to some extent, with the pore wall, and $CO_2$/$N_2$selectivity then exceeds the value of the Knudsen diffusion mechanism, while the membrane derived from TEOS alone has no $CO_2$selectivity. The silica membrane prepared from TEOS-ethanol-water-HCI solution showed that $CO_2$permeance was $2.5$\times$10^{-7}mol/s^{-1}.m^{-2}.Pa^{-1} at 30{\circ}C$ and $CO_2$/$N_2$selectivity was approximately 3. The $CO_2$permeance and selectivity was improved by enlarging the surface diffusion with modification of chemical affinity of the silica pores.

• 한국세라믹학회지
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• 제33권6호
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• pp.700-708
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• 1996

TiO2 membranes for microfiltration were prepared on $\alpha$-alumina support tube by slurry coating. The coating layer was obtained by flowing TiO2 slip on the inner surface of the alumina support. TiO2 membranes were heat-treated at 9$25^{\circ}C$ for 2 hrs. The thickness of the unsupported membrane was about 10${\mu}{\textrm}{m}$. The mean pore diameter of the membranes were 0.09 and 0.15${\mu}{\textrm}{m}$ respectively and the pure water flux was 900~1,200ι/m2.hr at room temperature and 1 bar. For a possible application of oily wastewater treatement an kerosene/wa-ter emulsion was separated in terms of flux and removal efficiency. In 60 min of operating time the flux of TiO2 membranes was 50~100 ι/m2.hr and removal efficiency was over 97% at 3kgf/cm2 of operating pres-sure and 600 ml/min of flow rate. TiO2 membranes could be recycled by reheat treatments at $600^{\circ}C$ for 2 hrs.

• 마이크로전자및패키징학회지
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• 제23권4호
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• pp.57-61
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• 2016

대용량 전력저장용 황화나트륨 기반의 전지를 개발함에 있어서 베타 알루미나 고체 전해질 튜브와 알파 알루미나 셀 캡 간의 물리적 접합을 위해서는 세라믹-세라믹 접합용 씰링 글라스 후막 페이스트가 필요하다. 본고에서는 글라스 프릿 분말의 입도, 열처리 조건이 씰링 글라스의 열처리 후 미세구조 특히 기공율과 그 분포에 미치는 영향을 연구하였다. 씰링 글라스 분말의 입자가 클수록 열처리 후의 글라스의 미세 조직상에서의 기공율 및 기공의 수가 감소하였으며, 열처리 온도가 증가 할수록 기공의 수가 감소하는 반면 기공의 크기는 증가함을 확인하였다. 이로써 글라스 씰란트의 제조에 있어서, 글라스 페이스트용 글라스 프릿 분말의 입자 크기와 씰링 열처리 온도의 적절한 선정에 의해 글라스 씰링부의 미세구조에서 기공율과 기공의 분포 및 기공의 수를 제어할 수 있음을 보여주었다.

• 한국세라믹학회지
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• 제30권3호
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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$0^{\circ}C$.

• 한국재료학회지
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• 제11권7호
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• pp.622-624
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• 2001

The CVD film of methoxysilane derived from diphenyldimethoxysilane(DPDMS) was formed on the outer surface of a porous ${\alpha}-alumina$ support tube coated(via dipping-drying-calcining) with a boehmite sol(0.3 mol-Al/L). The resulting silica membrane($500^{\circ}C,\;P_{fe}\;=\;130\;Pa$) showed a permeance of $5.18{\times}10^{-8}\;mol\;{\cdot}\;m^{-2}{\cdot}s^{-1}{\cdot}Pa^{-1}\;for\;CO_2$ and a permselectivity of 13.35 for $CO_2/N_2\;at\;30^{\circ}C$.