• 공업화학
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• 제35권1호
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• pp.1-7
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• 2024

NO, CO 및 CH₄의 동시 산화를 위한 4 종의 Mn-M/Al₂O₃ (M = Cu, Fe, Co, Ce) 촉매를 제조하여 산화 활성을 비교하고, 동시 산화활성이 가장 높은 Mn-Cu/Al₂O₃ 촉매에 대해 XRD, Raman, XPS, O₂-TPD 분석을 수행하였다. XRD 분석 결과, Mn-Cu/Al₂O₃ 촉매에서는 담지된 Mn과 Cu는 복합산화물로 존재하였다. Raman 및 XPS 분석을 통해 Mn-Cu/Al₂O₃ 촉매는 Mn-O-Cu 결합의 형성 과정에서 Mn 이온과 Cu 이온 간의 전자 수수가 일어남을 알 수 있었다. XPS O 1s 및 O₂-TPD 분석을 통해 Mn-Cu/Al₂O₃ 촉매는 Mn/Al₂O₃ 촉매에 비해 이동성이 우수한 흡착산소 종이 증가했음을 알 수 있었다. Mn-Cu/Al₂O₃ 촉매의 높은 동시 산화 활성은 이러한 결과에 기인한다고 판단된다. Mn-Cu/Al₂O₃ 촉매 상에서 NO는 CO와 CH₄ 산화를 촉진하지만, NO 산화는 억제되었다. 이는 NO로부터 산화된 NO₂가 CO 및 CH₄의 산화제로 사용되었기 때문이라고 추측된다. CO와 CH₄의 산화 반응은 경쟁하지만 촉매 활성 온도가 다르기 때문에 그 효과가 두드러지지 않았다.

• 한국분말재료학회지
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• 제5권4호
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• pp.334-339
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• 1998

In purpose of introducing the inverse magnetostrictive properties into the structural ceramics, $Al_2O_3$ based nanocomposites dispersed with nano-sized Ni-Co particles were studied. The composites were fabricated by the hydrogen reduction and hot-pressing of $Al_2O_3$ and NiO-CoO mixed powders. The mixtures were prepared by using Ni- and Co-nitrate $(Ni(NO_3)_2\;{\cdot}\;6H_2O\;and\;Co(NO_3)_2\;{\cdot}\6H_2O)$ as source materials for the Ni-Co particles. Microstructural observations revealed that nano-sized Ni-Co particles were dispersed homogeneously at $Al_2O_3$ grain boundaries. High strength above 1 GPa was obtained for the $Al_2O_3/10$ wt% Ni-Co nanocomposite fabricated by a controlled powder preparation process. The inverse magnetostrictive response to applied stress was obtained due to the presence of dispersed Ni-Co particles, which indicates a possibility to incorporate new functions into the structural ceramics without loosing the mechanical properties.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.276-277
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• 2006

In order to accelerate the sintering of Al-Bronze powder covered with passive oxide film, we focused on the way to add Al-Ca fluoride consisting of $AlF_3$ and $CaF_2$, examined the effect of the $CaF_2$ mixing rate in Al-Ca fluoride, the amount of the added Al-Ca fluoride and the sintering temperature on sintering properties of Al-Bronze powder and considered the mechanism of the sintering acceleration. Al-Bronze powder was sintered most effectively by adding Al-Ca fluoride with the $CaF_2$ mixing rate of 20mass%. If the amount of added fluoride was over 0.05mass% and the sintering temperature was over 1123K, the sintering acceleration of the Al-Bronze powder appears. Regarding the mechanism of the sintering acceleration, it was presumed that $Al_2O_3$ film on the surface of the Al-Bronze particles was removed in the process of the formation of gaseous AlOF by the reaction with $AlF_3$, and the reaction was accelerated further by the presence of the liquid phase which is formed in Al-Ca fluoride.

• Korean Chemical Engineering Research
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• 제55권2호
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• pp.156-162
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• 2017

CuO의 함량이 반응활성에 미치는 영향을 조사하기 위하여 CuO(x)/0.3Al-0.7Ce (x = 2~20 wt%) 촉매를 함침법으로 제조하고 저온 CO 산화반응을 수행하였다. CuO(10)/0.3Al-0.7Ce 촉매가 반응물 중 수분의 존재 유무에 관계없이 가장 우수한 반응활성을 나타내었다. 수분의 존재는 활성점에 CO와의 경쟁흡착으로 활성점이 감소하여 50% CO 전환율 온도인 $T_{50%}$가 약 $50^{\circ}C$ 고온으로 이동되어 관찰되었다. $N_2O$-적정실험으로 구한 구리 표면적과 CO-펄스 실험으로 계산된 격자산소의 양은 CuO의 함량 증가에 따라 증가하였고, CuO(10)/0.3Al-0.7Ce 촉매에서 최대화되었다. 이러한 특성 분석결과는 사용된 촉매의 CO 산화반응에 대한 $T_{50%}$의 경향과 잘 일치하였다. 위의 특성분석 결과로부터, CuO(x)/0.3Al-0.7Ce 촉매의 CO 산화반응에 대한 반응성은 구리 표면적과 격자산소의 양과 밀접하게 관련된다고 결론지을 수 있다.

• 한국재료학회지
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• 제17권8호
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• pp.447-451
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• 2007

We investigated the dependence of the various annealing conditions and thickness ($6\sim45nm$) of the Ti-doped $Al_2O_3$ coating on the electrochemical properties and the capacity fading of Ti-doped $Al_2O_3$ coated $LiCoO_2$ films. The Ti-doped-$Al_2O_3$-coating layer and the cathode films were deposited on $Al_2O_3$ plate substrates by RF-magnetron sputter. Microstructural and electrochemical properties of Ti-doped-$Al_2O_3$-coated $LiCoO_2$ films were investigated by transmission electron microscopy (TEM) and a dc four-point probe method, respectively. The cycling performance of Ti-doped $Al_2O_3$ coated $LiCoO_2$ film was improved at higher cut-off voltage. But it has different electrochemical properties with various annealing conditions. They were related on the microstructure, surface morphology and the interface condition. Suppression of Li-ion migration is dominant at the coating thickness >24.nm during charge/discharge processes. It is due to the electrochemically passive nature of the Ti-doped $Al_2O_3$ films. The sample be made up of Ti-doped $Al_2O_3$ coated on annealed $LiCoO_2$ film with additional annealing at $400^{\circ}C$ had good adhesion between coating layer and cathode films. This sample showed the best capacity retention of $\sim92%$ with a charge cut off of 4.5 V after 50 cycles. The Ti-doped $Al_2O_3$ film was an amorphous phase and it has a higher electrical conductivity than that of the $Al_2O_3$ film. Therefore, the Ti-doped $Al_2O_3$ coated improved the cycle performance and the capacity retention at high voltage (4.5 V) of $LiCoO_2$ films.

• 공업화학
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• 제20권5호
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• pp.522-526
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• 2009

다양한 금속(Ru, Mn, Co, Fe)을 $Al_2O_3$와 $CeO_2$에 담지한 촉매를 이용하여 1,2-Dichlorobenzen (1,2-DCB) 제거를 위한 촉매산화 실험을 실시하였다. 이와 더불어 동시에 NOx 제거가 이루어져 단일 촉매층에서 산화/환원 이원 기능이 가능한 촉매를 연구하고자 하였다. 실험결과 1,2-DCB 산화제거효율은 Ru/Co/$Al_2O_3$, Mn-Fe/$CeO_{2}$, 상용촉매인 Cr/$Al_2O_3$ 순으로 나타났다. 또한 1,2-DCB 산화제거효율이 가장 우수하였던 Ru/Co/$Al_2O_3$는 Chlorobenzene (CB)의 분해실험에서도 VOC 제거에 있어서 잘 알려진 Pt-Pd/$Al_2O_3$ 보다 우수한 활성을 나타내었다. 또한 $Cl_2$와 같은 생성물에 의하여 활성의 저하 및 황에 대한 내피독성과 내구성에서 우수한 결과를 얻을 수 있었다. NOx 제거에 있어서도 $260^{\circ}C$에서 NOx 전환율이 70% 정도로 나타났다.

• 한국세라믹학회지
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• 제53권3호
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• pp.338-342
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• 2016

ZnO thin film co-doped with F and Al was prepared on a glass substrate via simple non-alkoxide sol-gel spin coating. For a fixed F concentration, the addition of Al co-dopant was shown to reduce the resistivity mainly due to an increase in electrical carrier density compared with ZnO doped with F only, especially after the second post-heat-treatment in a reducing environment. There was no effective positive contribution to the reduction in resistivity due to the mobility enhancement by the addition of Al co-dopant. Optical transmittance of the ZnO thin film co-doped with F and Al in the visible light domain was shown to be higher than that of the ZnO thin film doped with F only.

• 열처리공학회지
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• 제23권6호
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• pp.331-337
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• 2010

Aluminum nitride (AlN) thin films containing various amounts of Co content have been deposited by using a two-facing targets type sputtering (TFTS) system. The deposited films were also annealed successively and isothermally at different temperatures. Annealing treatment can control the physical properties as well as the microstructure of AlN films with Co particles. High magnetization and high resistivity are obtainable in AlN films containing dispersed Co particles. The coercivity of the films does not depend on annealing time, but it increases with increasing annealing temperature due to the increase of the grain size. A high saturation magnetization of 46 kG and resistivity of 2200 ${\mu}{\Omega}$-cm was obtained for AlN films containing 25 at% Co.

• 한국표면공학회지
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• 제27권2호
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• pp.91-98
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• 1994

For the plasma sprayed as well as the EB-PVD thermal barrier coatings, the fracture paths within the oxidation products developed at the interface between the partially stabilized zirconia ceramic coating and NiCoCrAlY bond coat during cyclic thermal oxidation has been investigated. It was observed that the fracture in the oxidation products primarily took place within the oxide such as $Ni_{1-x}Co_3(Al_,Cr)_2O_4$ or at the interface between the oxide and $Al_2O_3$. It was found that Al2O3 developed first, followed by the Ni/Co/Cr rich oxides such as ,,$Ni_{1-x}Co_x(Al_,Cr)_2O_4$ $Cr_2O_3$and NiO at the interface between the ceramic coating and the bond coat in a cyclic high temperature environment. It was therfore concluded that the formation of the oxide containing Ni, Cr and Co was a life-limiting event for thermal barrier coatings during cyclic thermal oxidation.

• 한국표면공학회지
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• 제34권5호
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• pp.494-498
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• 2001

Ferromagnets(FM)-Al-$O_{x}$ -Ferromagnets (FM) tunneling junctions were evaluated by changing the fabricating conditions of an Al-X$/_{x}$ layer. The junction composed of a thicker Al-$O_{x}$ shows the low resistance and the stable MR ratio about 16% in a wide range of oxidation time. For the junctions with the thinner Al-$O_{x}$ , they showed a fast increase of the barrier width as an increase of an oxidation time and exhibited a strong bias dependence. As oxidation time increased, the coercivity ($H_{c}$ ) of bottom Co layer increased gradually due to the local oxidation of Co bottom layer at a interface. However, the small formation of Co oxide did not largely influence on the deterioration of MR ratio.