• Journal of Hydrogen and New Energy
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• v.17 no.2
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• pp.204-211
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• 2006

The electrolyte in the solid oxide fuel cell must be dense enough to avoid gas leakage and thin enough to reduce the ohmic resistance. In order to manufacture the thin and dense electrolyte layer, 8 mol% $Y_2O_3$ stabilized-$ZrO_2$ (8YSZ) electrolyte layers were coated on the porous tubular substrate by the novel vacuum slurry dip-coating process. The effects of the slurry concentration, presintering temperature, and vacuum pressure on the thickness and the gas permeability of the coated electrolyte layers have been examined in the vacuum slurry coating process. The vacuum-coated electrolyte layers showed very low gas permeabilities and had thin thicknesses. The single cell with the vacuum-coated electrolyte layer indicated a good performance of $495\;mW/cm^2$, 0.7 V at $700^{\circ}C$. The experimental results show that the vacuum dip-coating process is an effective method to fabricate dense thin film on the porous tubular substrate.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.4
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• pp.341-347
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• 2008

Laminated LTCC components of high integrity, fabricated by thick film process, are applied to industrial field of IT technology along with miniaturization trend of electronic devices. Dispersion states were examined by several evaluation methods with MLS-22, which is one of commercial LTCC powders, to achieve optimal dispersion as basis for stable LTCC fabrication process. Slurry viscosity, surface roughness of dip-coated slide glass, sedimentaion of slurry, and SEM observation of dried surface were utilized with respective amount change of various commercial dispersants. Among these commercial dispersants, optimal dispersion state was obtained with 0.4 wt% of BYK-111, from the results of various evaluation methods.

• Proceedings of the Materials Research Society of Korea Conference
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• 2008.11a
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• pp.35.2-35.2
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• 2008

• Journal of the Korean Electrochemical Society
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• v.8 no.4
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• pp.162-167
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• 2005

Using Pechini method, we synthesized the $La_{0.6}Ca_{0.41}CrO_3$ (LCC41) and $La_{0.8}Sr_{0.05}Ca_{0.15}CrO_3$ (LSCC) powders for slurry dip coating, and $La_{0.75}Ca_{0.27}CrO_3$ (LCC27) powder for air plasma spray coating. The sintering property of the powders and their coating properties were investigated. The average particle sizes of the LCC41, LSCC, LCC27 were 0.6, 0.9, $1.5{\mu}m$, respectively. The relative density of LCC41 bulk was to be found about 98%. The LSCC coating on anode support prevented Ca migration of the coated LCC41 on the anode some or less, which was confirmed from EDS result. The air plasma spray-coated LCC27 with the dip-coated LCC41 were more dense and showed better electrical conductivity than those of the air plasma spray-coated LCC27 and the dip-coated LSCC and LSCC41. The LCC41 and LCC27 showed good electrical conductivities, but the LSCC had a poor electrical conductivity probably due to low sinterability

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.218-221
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• 2000

Currently, Bi-2223 HTS tape is capable of being fabricated in longer than 100m length by industrial processes. But there are some problems in heat treatment of the degree of longer than 100m tape, which is in term of volume occupied with specimen in furnace. The effects of ceramic coating with variable slurry states were studied in Bi-2223 high-temperature superconductor. The HTS tapes coated with oxide were prepared by using dip-coating method on slurry state. Critical current(I$_{c}$) of tapes coated with ceramic materials were equal with 11.5A at 77K after first heat treatment as different slurries. For final heat treatment, Critical current of HTS tapes coated with zirconia oxide mixed in PMMA and PVA organic solute were 20.8A at 77K. The breakdown voltage of HTS tapes coated with zirconia oxide were 3kV in air and 4~7kV in L$N_2$.>.

• Journal of the Korean Ceramic Society
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• v.54 no.3
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• pp.200-204
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• 2017

Molybdenum (Mo), an electrode material of alkali metal thermal-to-electric converters (AMTEC), facilitates grain growth behavior and forms Mo-Na-O compounds at high operating temperatures, resulting in reduced performance and shortened lifetime of the cell. Mo/TiN composite materials have been developed to provide a solution for such issues. Mo is a metal that possesses excellent electrical properties, and TiN is a ceramic compound with high-temperature durability and catalytic activity. In this study, a dip-coating process with an organic solvent-based slurry was used as an optimal coating method to achieve homogeneity and stability of the electrodes. Cell performance was evaluated under various conditions such as the number of coatings, ranging from 1 to 3 times, and heat treatment temperatures of $800-1100^{\circ}C$. The results confirmed that the cell yielded a maximum power of 9.99 W for the sample coated 3 times and heat-treated at $900^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.46 no.5
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• pp.534-539
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• 2009

Reaction Bonded Silicon Carbide(RBSC) has been used for engineering ceramics due to low-temperature fabrication and near-net shape products with excellent structural properties such as thermal shock resistance, corrosion resistance and mechanical strength. Recently, attempts have been made to develop hot gas filter with gradient pore structure by RBSC to overcome weakness of commercial clay-bonded SiC filter such as low fracture toughness and low reliability. In this study a fabrication process of porous RBSC with multi-layer pore structure with gradient pore size was developed. The support layer of the RBSC with multi-layer pore structure was fabricated by conventional Si infiltration process. The intermediate and filter layers consisted of phenolic resin and fine SiC powder were prepared by dip-coating of the support RBSC in slurry of SiC and phenol resin. The temperature of $1550^{\circ}C$ to make Si left in RBSC support layer infiltrate into dip-coated layer to produce SiC by reacting with pyro-carbon from phenol resin.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.200-200
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• 2003

고체산화물 연료전지(SOFC)에서 사용되는 연결재의 주 기능은 각 단위 셀의 연료극과 다음 셀의 공기극을 전기적으로 연결하여, 공기와 사용연료의 분리역할을 하기 위하여 사용된다. SOFC용 연결재는 다른 구성요소 소재보다, 높은 전자 전도성, 낮은 이온전도성, 우수한 기계 적강도가 요구되며, SOFC는 고온에서 작동되기 때문에, 상온에서 작동온도까지 다른 요소 소재들과 유사한 열팽창계수와 물리, 화학적으로 안정성이 요구된다. 현재 연결재 제조기술은 EVD, CVD, plasma spraying, tape casting 등 다양하게 연구되고 있으며, 본 연구는 세라믹 연결재 증착방법 중 저렴한 비용으로 대량 생산이 용이한 습식법(dip coaling)을 적용하여, 연료극 지지체식 flat-tube형 고체산화물 연료전지의 지지체를 위해 세라믹 연결재를 제조하고, 그 특성을 연구하였다. 세라믹 연결재로써 선정한 합성조성은 LaCr $O_3$에 Ca이 치환 고용된 L $a_{0.6}$C $a_{0.41}$Cr $O_3$으로 pechini법으로 합성하였다. 합성된 조성은 100$0^{\circ}C$에서 5시간 하소후 가속 Ball Milling하여 0.5$\mu\textrm{m}$의 평균입자크기를 얻을 수 있었다. XRD 상분석결과 perovskite상 (L $a_{1-x}$ Ca/x/Cr $O_3$)과 CaCr $O_4$를 얻을 수 있었다. slurry를 제조하여 막의 밀착성을 증진시키기 위해 sand blasting시킨 flat tube지지체에 진공펌프를 이용하여 소재내부와 외부의 압력차로 dip coating한 후, 140$0^{\circ}C$로 소결 하였다. coating 결과 박리현상은 없었으나, 표면과 단면의 SEM분석결과 다소 porous한 박막층이 형성되었으며, Ca이온이 지지체로 permeation되는 현상이 발생하였다. 이와 같은 결과로부터 보다 치밀한 박막생성을 위해, slurry 제조조건을 변화시켰으며, Ca이온의 migration을 막기 위해 barrier layer를 이용하였다 완전 소결된 지지체는 가스투과도와 전기전도도측정을 통하여 특성을 평가하였다.였다.다.

• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.525-530
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• 2019

The performance and stability of solid oxide fuel cells (SOFCs) depend on the microstructure of the electrode and electrolyte. In anode, porosity and pore distribution affect the active site and fuel gas transfer. In an electrolyte, density and thickness determine the ohmic resistance. To optimizing these conditions, using costly method cannot be a suitable research plan for aiming at commercialization. To solve these drawbacks, we made high performance unit cells with low cost and highly efficient ceramic processes. We selected the NiO-YSZ cermet that is a commercial anode material and used facile methods like die pressing and dip coating process. The porosity of anode was controlled by the amount of carbon black (CB) pore former from 10 wt% to 20 wt% and final sintering temperature from $1350^{\circ}C$ to $1450^{\circ}C$. To achieve a dense thin film electrolyte, the thickness and microstructure of electrolyte were controlled by changing the YSZ loading (vol%) of the slurry from 1 vol% to 5 vol. From results, we achieved the 40% porosity that is well known as an optimum value in Ni-YSZ anode, by adding 15wt% of CB and sintering at $1350^{\circ}C$. YSZ electrolyte thickness was controllable from $2{\mu}m$ to $28{\mu}m$ and dense microstructure is formed at 3vol% of YSZ loading via dip coating process. Finally, a unit cell composed of Ni-YSZ anode with 40% porosity, YSZ electrolyte with a $22{\mu}m$ thickness and LSM-YSZ cathode had a maximum power density of $1.426Wcm^{-2}$ at $800^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.41 no.3
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• pp.229-234
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• 2004

In this study, we proposed new forming process for a porous ceramic body with unique pore structure. h tubular-type porous NiO-YSZ body with radially aligned pore channels was prepared by freeze-drying of aqueous slurry. A NiO-YSZ slurry was poured into the mold, which was designed to control the crystallization direction of the ice, followed by freezing. Thereafter the ice was sublimated at a reduced pressure. SEM observations revealed that the NiO-YSZ porous body showed aligned large pore channels parallel to the ice growth direction, and fine pores are formed around the outer surface of the tube. It was considered that the difference in the ice growth rate during the freezing process resulted in such a characteristic microstructure. Bilayer consisting of dense thin electrolyte film of YSZ onto the tubular type porous body has been successfully fabricated using a slurry-coating process followed by co-firing. It was regarded that the obtained bilayer structure is suitable for constructing electrode-support type electrochemical devices such as solid oxide fuel cells.