• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.128-128
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• 1999

산소이온 전도체로 잘 알려진 Yttira-Stabilizd Ziroconia(TSZ)는 연료전지, oxygen pumps, chemical gas sensor 등 다양한 electrochemical divices에 이용되는 고체 전해질의 하나이다. 특히 YSZ는 oxygen 및 oxygen과 평형상태에 있는 gas들을 검출하는 sensor의 electrolyte로서 가장 많이 쓰이고 있다. 현재 상용화되어 있는 YSZ Sensor는 전통적인 bulk 형태의 ceramic으로 제작된 것으로 충분한 ionic conductivity를 얻기 위해서는 $600^{\circ}C$이상의 operating temperature를 필요로 하나 YSZ를 박막으로 제조시 낮은 operating temperature를 뿐만 아니라 sensor의 소형화, 낮은 ohmic loss 및 다양한 응용이 가능한 장점을 가질 수 있다. 본 실험에서는 산소 이온 전도체로서 8mol%-YSZ 고체전해질을 RF-magnetron bias sputtering 법을 이용하여 증착하였다. 제조된 YSZ 박막을 이용한 산소감응 센서셀 구조는 SiO2/Ni-NiO/Pt/YSZ/Pt-기판이다. 센서셀의 정상상태에서의 기전력(electromotive force ; EMF)을 산소분압(Po:1.013$\times$103Ta ~1.013$\times$105Pa)과 측정온도(30$0^{\circ}C$~$700^{\circ}C$)를 변화시키며 측정하였다. 이론적인 기전력과 측정값 사이의 편차는 Po:1.565$\times$104Pa 이하의 산소분압에서는 컸지만 이 이상의 분압에서는 이론치에 근접한 값을 가졌다. 증착한 YSZ와 Ni-NiO 박막의 구조는 X-ray diffractometer(XRD)를 이용하여 결정구조를 알아 보았고, TSZ 박막의 표면 morphology 관찰은 Scanning electron microscopy(SEM) 이용하였다. 박막의 조성분석은 X-ray energy dispersive analysis(EDX)을 사용하였다.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.1
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• pp.1-5
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• 2006

The effect of A/B moi ratios and sintering temperatures on dielectric properties and microstructure of $(Ba_{0.93}Ca_{0.07})_m(Ti_{0.82}Zr_{0.18})O_3$ ceramics were investigated. The dielectric constant decreased with increasing the A/B mol ratio. However, the dielectric loss is improved. As the dielectric properties of A/B mol ratio with m = 1.009 at sintered temperature $1260^{\circ}C$, we obtained dielectric constant 12,800, dielectric loss $3.5\%$ and Y5V temperature characteristics. Highly reliable Ni-MLCCs, 1.6mm$(length){\time}0.8mm(width){\time}0.8mm$(height) with capacitance of 1.23 ${\mu}F$ and 야ssipation loss of $5.2\%$ were obtained employing dielectric material composed of $(Ba_{0.93}Ca_{0.07})_{1.009}(Ti_{0.82}Zr_{0.18})O_3$ - $MnO_2\;0.2wt\%-Y_2O_3\;0.18wt\%,\;-\;SO_2\;0.15wt\%-(Ba_{0.4}Ca_{0.6})SiO_3\;1wt\%$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.12
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• pp.803-808
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• 2016

In this work, one dimension $In_2O_3$ nanostructures as detecting materials for indoor toxic gases were synthesized by an electrospinning process. The morphology of electrospun $In_2O_3$ nanofibers was controlled by electrolyte composition, applied voltage and working distance between a nozzle and a substrate. The synthesized $In_2O_3$ nanofibers-based paste with/without carbon black additives was prepared for the integration on a sensor device. The integration of $In_2O_3$ sensing materials was conducted by a hand-printing of the paste into the interdigit Au electrodes patterned on Si wafer. Gas sensing properties on CO and HCHO gases were characterized at $300^{\circ}C$. The evaluated sensing properties such as sensitivity, response time and recovery time were improved in $In_2O_3$ nanofiber pastes with carbon black, compared to the paste without carbon black.

• Journal of Radiation Industry
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• v.3 no.1
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• pp.7-11
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• 2009

Hard magnet was usually used by coating $SiO_2$ ceramic thick films followed by the thermal annealing process. In this work, the alternative annealing process for NdFeB magnets using e-beam sources (1~2 MeV, 50~400 kGy) was investigated. NdFeB magnets was coated with ceramic thick films using the spray method. The optimal annealing parameter for e-beam source reveals to be 1 MeV and 300 kGy. The sample prepared at 1 MeV and 300 kGy was characterized by the analysis of the surface morphology, film hardness, adhesion and chemical stability. The mechanical property of thick film, especially film hardness, is better than that of thermal annealed samples at $180^{\circ}C$. As a result, e-beam annealing process will be one of candidate and attractive heat treatment process. In future, manufacturing process will be carried out in cooperation with the magnet company.

• Resources Recycling
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• v.31 no.5
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• pp.52-58
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• 2022

Silicon carbide powder was prepared from carbon black and silicon recovered from waste solar panels. In the solar power generation market, the number of crystalline silicon modules exceeds 90%. As the expiration date of a photovoltaic module arrives, the development of technology for recovering and utilizing silicon is very important from an environmental and economic point of view. In this study, silicon was recovered as silicon carbide from waste solar panels: 99.99% silicon powder was recovered through purification from a 95.74% purity waste silicon wafer. To examine the synthesis characteristics of SiC powder, purified 99.99% silicon powder and carbon powder were mixed and heat-treated (1,300, 1,400 and 1,500 ℃) in an Ar atmosphere. The characteristics of silicon and silicon carbide powders were analyzed using particle size distribution analyzer, XRD, SEM, ICP, FT-IR, and Raman analysis.

• Membrane and Water Treatment
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• v.15 no.1
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• pp.21-29
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• 2024

1H,1H,2H,2H-perfluorodecytriethoxysilane (C₁₆H₁₉F₁₇O₃Si) be successfully applied to the hydrophobic modification of Al₂O₃ tubular ceramic membrane. Taking the concentration of modification solution, modification time, and modification temperature as factors, orthogonal experiments were designed to study the hydrophobicity of the composite membranes. The experiments showed that the modification time had the greatest impact on the experimental results, followed by the modification temperature, and the modification solution concentration had the smallest impact. Concentration of the modified solution 0.012 mol·L^-1, modification temperature 30 ℃ and modification time 24 h were considered optimal hydrophobic modification conditions. And the pure water flux reached 274.80 kg·m^-2·h^-1 at 0.1MPa before hydrophobic modification, whereas the modified membrane completely blocked liquid water permeation at pressures less than 0.1MPa. Air gap membrane distillation experiments were conducted for NaCl (2wt%) solution, and the maximum flux reached 4.20 kg·m^-2·h^-1, while the retention rate remained above 99.8%. Given the scarcity of freshwater resources in coastal areas, the article proposed a system for seawater desalination using air conditioning waste heat, and conducted preliminary research on its freshwater production performance using Aspen Plus. Finally, the proposed system achieved a freshwater production capacity of 0.61 kg·m^-2·h^-1.

• Korean Journal of Materials Research
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• v.11 no.4
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• pp.290-293
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• 2001

The SrBi$_2$Nb$_2$O$_{9}$ (SBN) thin films were deposited on p-type(100) Si substrates by rf magnetron sputtering to confirm the Possibility of Pt/SBN/Si structure for the application of nondestructive read out ferroelectric random access memory (NDRO- FRAM). The SBN thin films were deposited by co-sputtering method with Sr$_2$Nb$_2$O$_{7}$ (SNO) and Bi$_2$O$_3$ ceramic targets. The SBN thin films deposited at room temperature were annealed at $700^{\circ}C$ for 1hr in $O_2$ ambient. The structural and electrical properties of SBN with different power ratios of targets were measured by x-ray diffraction(XRD), scanning electron microscopy(SEM), capacitance-voltage(C-V), and current-voltage(I-V). The C-V curves of the SBN films showed hysteresis curves of a clockwise rotation showing ferroelectricity. When the Power ratio of the SNO/Bi$_2$O$_3$ targets was 120 W/100 W, the SBN thin films had excellent electrical properties. The memory window of SBN thin film was 1.8 V-6.3 V at applied voltage of 3 V-9 V and the leakage current density was 1.5 $\times$ 10$^{-7}$ A/$\textrm{cm}^2$ at applied voltage of 5 V The composition of SBN thin films was analysed by electron probe X-ray micro analyzer(EPMA) and the atomic ratio of Sr:Bi:Nb with pawer ratio of 120 W/100 W was 1:3:2.

• Journal of the Korean Ceramic Society
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• v.39 no.2
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• pp.145-152
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• 2002

Four commercial alumina powders having different particle size of $0.5{\mu}m,\;2.8{\mu}m,\;12{\mu}m,\;and\;45{\mu}m$ were presintered at 1120$^{\circ}C$ for 2h and then lanthanum aluminosilicate glass was infiltrated at 1100$^{\circ}C$ for 2h in the interval of 0.1h to investigate the penetration kinetic of the glass into the alumina preforms. The infiltration distance is parabolic with respect to time as described by the Washburn equation and the penetration rate constant, K, increases with raising the alumina particle size. The strength of glass-alumina composites increases as the alumina particle size reaches to 2.8${\mu}m$ due to the increase in packing, however, decreases with further increasing the alumina particle size. The fracture toughness of the composites rises with increasing the alumina particle size due to the crack bowing and the interaction between crack and alumina particles.

• The Korean Journal of Ceramics
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• v.3 no.2
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• pp.105-109
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• 1997

The effects of surface conditions of the C-2 cemented carbide substrate on the adhesion of diamond film were investigated. The substrates were pretreated for different times with Murakami's reagent and then the acid solution of an H2SO4-H2O2. The adhesion strength was estimated by a peeling area around the Rockwell-A indentation. The cutting performance of the diamond-coated tools was evaluated by measuring flank wears in dry turning of Al-17% Si alloy. The morphology of deposited diamond crystallites was dominated by (111) and (220) surfaces with a cubooctahedral shape. The diamond film quality was hardly affected by the surface conditions of the substrate. The variation of tool life with longer substrate etching times resulted from a compromies between the increase of film adhesion at the interface and the decrease of toughness at the substrate surface. The coated tools were mainly deteriorated by chipping and flaking of the diamond film form a lock of adhesion strength, differently from the wear phenomena of PCD tools.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.186-189
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• 2008

Solar simulator를 이용한 메탄의 수증기 개질은 집광된 태양에너지를 이용하기 위한 목적으로 수행되었다. 본 연구에서는 이와 같은 태양열에너지의 화학적 축열을 실시하기 위해 Solar Simulator를 이용한 메탄의 수증기 개질을 연구하였다. 태양열 모사 램프로 1.2kW급 Xenon-arc lamp를 사용하였다. 반응기는 앞면의 Quartz Window와 촉매지지층으로 구성되어 있다. 램프의 빛은 Quartz Window를 통하여 촉매층에 직접적으로 방사되고, 방사된 빛으로 촉매지지층에서 흡열반응이 일어난다.메탄의 수증기개질 반응은 고온에서 일어나기 때문에 촉매지지체를 열에 강한 SiC로 만들어진 Ceramic foam을 사용하였다. 이 촉매지지체에 촉매를 Wash-coat하여 사용하였으며, 담지된 촉매는 Ni을 활성성분으로 하는 ICI 46-6을 사용하였다. 반응기는 318 SUS 재질로 제작되었으며, 반응기 외부는 Insulation을 하여 열손실을 감소시켰다. 실험은 온도와 공간속도에 따른 Solar Steam reforming의 반응특성을 분석하였다.