• 청정기술
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• 제28권3호
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• pp.218-226
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• 2022

최근 선진국들은 수소경제 및 탄소중립 사회로의 전환을 위해 수소에너지의 수요가 급격히 증가하고 있으며, 이산화탄소(CO₂)를 배출이 없는 친환경적인 수소(H₂) 생산 기술에 대한 관심이 높아지고 있다. 본 연구에서는 암모니아(NH₃) 분해 수소 제조를 위해 루테늄 알루미나(Ru/Al₂O₃) 분말 촉매와 함께 알루미나 졸(alumina sol)의 무기바인더(inorganic binder)와 메틸 셀룰로오스(methyl cellulose)의 유기바인더(organic binder)를 사용하여 딥 코팅(dip coating) 방법으로 루테늄 알루미나 메탈 모노리스 코팅 촉매를 제조하였다. 딥 코팅을 위한 촉매 슬러리의 최적 비율로 촉매와 무기바인더의 중량 비율을 1:1로 고정하여 유기바인더 0.1일 때 1회 딥 코팅 시 촉매 코팅양은 61.6 g L^-1이다. 이때 메탈모노리스 표면에 코팅된 촉매 층의 균일한 두께 (약 42 ㎛)와 결정상을 주사전자현미경(Scanning Electron Microscope, SEM)과 X-ray 회절분석(X ray diffraction, XRD)을 통해 확인하였다. 또한, 암모니아 분해 수소 제조의 최적 공정조건을 찾고자 반응표면분석법(Response Surface Method, RSM)을 이용하여 반응온도와 공간속도의 독립변수에 따른 암모니아 전환율에 대한 수치 최적화 회귀식 모델을 계산하였다. 이러한 결과로부터 암모니아 분해 수소생산을 위한 상업적 규모의 공정운전 기본설계 자료로 활용이 가능하다.

• 한국수소및신에너지학회논문집
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• 제17권1호
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• pp.69-74
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• 2006

Thick film $H_2$ sensors were fabricated using $SnO_2$ loaded with $Ag_2O$ and $PtO_x$. The composition that gave the highest sensitivity for $H_2$ was in the weight% ratio of $SnO_2 : PtO_x : Ag_2O$ as 93 : 1 : 6. The nano-crystalline powders of $SnO_2$ synthesized by sol-gel method were screen printed with $Ag_2O$ and $PtO_x$ on alumina substrates. The fabricated sensors were tested against gases like $H_2$, $CH_4$, $C_3H_8$, $C_2H_5OH$ and $SO_2$. The composite material was found sensitive against $H_2$ at the working temperature $130^{\circ}C$, with minor interference of other gases. The $H_2$ gas as low as 100 ppm can be detected by the present fabricated sensors. It was found that the sensors based on $SnO_2-Ag_2O-PtO_x$ system exhibited the high performance, high selectivity and very short response time to $H_2$ at ppm level. These characteristics make the sensor to be a promising candidate for detecting low concentrations of $H_2$.

• Korean Chemical Engineering Research
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• 제49권6호
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• pp.726-731
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• 2011

F-T 반응이 공업적으로 활용되기 위해서는 촉매의 대량 합성 및 성형체의 기계적 강도가 매우 중요한 변수로 적용될 수 있다. 따라서 본 논문에서는 F-T 합성반응용 촉매로 잘 알려진 Fe 계열 촉매의 성형체 제조를 위한 바인더의 영향을 알아보기 위한 연구를 수행하였다. 촉매 바인더로는 무기바인더와 유기바인더를 사용하여 촉매 성형체를 제조하였다. 무기바인더 및 유기바인더의 종류와 함량에 따른 성형촉매의 물리화학적 특성을 XRD, BET, PSD, TPR, UTM으로 분석하였으며, F-T 합성 반응성에 대한 영향을 관찰함으로써 최적의 성형 촉매 제조 조성을 확립할 수 있었다.

• 한국세라믹학회지
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• 제38권9호
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• pp.834-838
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• 2001

고체 전해질로 많이 사용되는 이트리아로 안정화된 입방정형(cubic) 지르코니아의 기계적 강도를 향상시키기 위하여, 단사형(monoclinic) 지르코니아(m-$ZrO_2$)를 원료로 지르코니아　 안정화시키는 이트리아와 지르코니아의 낮은 기계적 강도를 향상시켜 주기 위한 알루미나를 Yag($Y_3Al_5O_{13}$)졸의 형태로 첨가하여, 졸 형태로 첨가된 이트리아와 알루미나가 입방정 지르코니아 소결체의 기계적, 전기적 특성에 미치는 영향을 조사하였다. 17.8 wt% Yag(6.3mol% $Y_2O_3$)가 첨가된 경우 파괴인성은 3.62MPa${\cdot}m^{1/2}$, 파괴강도는 447MPa로 8mol%의 이트리아로 안정화된 지르코니아(TZ8Y)의 1.44MPa${\cdot}m^{1/2}$, 270MPa에 비하여 기계적 특성이 현저히 향상되었으나, 950$^{\circ}$C, 공기분위기에서의 전기전도도는 0.057${\Omega}^{-1}cm^{-1}$로 TZ8Y에 비해 반 정도로 낮아졌으며, 21.6wt% Yag(8.0mol% $Y_2O_3$)가 첨가된 경우에는 파괴인성은 2.93MPa${\cdot}m^{1/2}$, 파괴강도는 388MPa로 TZ8Y에 비하여 향상되었고, 전기전도도는 0.076${\Omega}^{-1}cm^{-1}$을 나타내었다.

• Journal of Korean Vacuum Science & Technology
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• 제4권4호
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• pp.93-96
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• 2000

Microchannel plates (MCPs) have been developed by introducing new materials and process technologies. Main body was made of alumina by programmable punching, laminating, and firing. The channel walls of pore arrays of an MCP were deposited with thin films by electroless copper plating and sol-gel process. Our MCP has advantages such as easy fabrication, durability, high temperature endurance, and applicability to the large size comparing with the conventional MCPs. Experiments on the brightness of an MCP incorporated FED revealed that the FED with a MCP is three to four times brighter than a conventional FED. Moreover, the focusing in a FED is improved. Incorporating an MCP into a FED is one of promising methods to enhance the characteristics of the FED. In addition, amplification yield of the MCP is measured for varying the aspect ratio and the input current.

• Transactions on Electrical and Electronic Materials
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• 제10권2호
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• pp.49-52
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• 2009

Barium strontium calcium titanate powders were prepared with the sol-gel method. Ferroelectric $(Ba_{0.54}Sr_{0.36}Ca_{0.1})TiO_3$(BSCT) thick films were fabricated by the screen-printing method on alumina substrate. Then we investigated the structural and dielectric properties of the BSCT thick films at different sintering temperatures. The thermal analysis showed that the BSCT polycrystalline perovskite phase formed at around $660^{\circ}C$. The X-ray diffraction analysis showed a cubic perovskite structure with no second phase present in all of the BSCT thick films. The average grain size and the thickness of the specimens sintered at $1450^{\circ}C$ were about $1.6{\mu}m$ and $45{\mu}m$, respectively. The relative dielectric constant increased and the dielectric loss decreased as the sintering temperature was increased; for BSCT thick films sintered at $1450^{\circ}C$ the values of the dielectric constant and the dielectric loss were 5641 and 0.4%, respectively, at 1 kHz.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.180-181
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• 2009

$(Ba_{0.6},Sr_{0.3}Ca_{0.1})TiO_3$ powders, which were prepared by sol-gel method using a solution of Ba-acetate, Sr-acetate and Ca-acetate and Ti iso-propoxide, $(Ba_{0.6},Sr_{0.3}Ca_{0.1})TiO_3$ array thick films doped with 0.1 mol% $MnCO_3$ and $Yb_2O_3$ (0.1~0.7 mol%) were fabricated by the screen printing method on the alumina substrate. And the structural and electrical properties as a function of $Yb_2O_3$ amount were investigated. The thickness of all (Ba,Sr,Ca)$TiO_3$ thick films was approximately 60mm. The Curie temperature of doped with 0.1 mol% $Yb_2O_3$ specimen was $45^{\circ}C$, and the dielectric constant and at this temperature was 1062.

• 한국세라믹학회지
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• 제42권6호
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• pp.384-390
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• 2005

[ ${\alpha}-Al_2O_3$ ] precursor was synthesised by sol-gel method using aluminum sulfate, sodium sulfate and sodium carbonate as law materials. The flaky ${\alpha}-Al_2O_3$ crystals were prepared by heating using precursor about $1,050^{\circ}C$. In this study, the effect of some transition-metal sulfate ($FeSO_4,\;SnSO_4,\;ZnSO_4$) addition have been investigated. When iron sulfate was added, it could see that act on impurities in crystal growth process. In case of tin sulfate, distribution of Platelets was very broad. When flaky ${\alpha}-Al_2O_3$ crystals were prepared zinc sulfate addition, thickness, size, and distribution of platelets was suited to industrial application. The average diameter of flaky ${\alpha}-Al_2O_3$ crystals was about 20 $\mu$m, and its thickness was about 0.3 $\mu$m. Increasing addition of zinc sulfate, thickness of ${\alpha}-Al_2O_3$ platelet was decreased.

• 센서학회지
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• 제15권3호
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• pp.168-172
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• 2006

Potentiometric $CO_{2}$ sensors were fabricated using a NASICON ($Na_{1+x}Zr_{2}Si_{X}P_{3-X}O_{12}$, 1.8 < x < 2.4) thick film and auxiliary layers. The powder of a precursor of NASICON with high purity was synthesized by a sol-gel method. By using the NASICON paste, an electrolyte was prepared on the alumina substrate by screen printing and then sintered at $1000^{\circ}C$ for 4 h. A series of $Na_{2}CO_{3}-CaCO_{3}$ auxiliary phases were deposited on the Pt sensing electrode. The electromotive force (emf) values were linearly dependent on the logarithm of $CO_{2}$ concentration in the range between 1,000 and 10,000 ppm. The device attached with $Na_{2}CO_{3}-CaCO_{3}$ (1:2 in mol.%) showed good sensing properties in the low temperatures.

• 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 $CO_2/N_2\;at\;30^{\circ}C$.