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Spin-coating 공정에 의해 제조된 음극 지지형 고체산화물 연료전지
유지행,이희락,우상국,Yu, Ji-Haeng,Lee, Hee-Lak,Woo, Sang-Kuk 한국세라믹학회 2007 한국세라믹학회지 Vol.44 No.12
NiO-YSZ anode-supported single cell was prepared by spin-coating YSZ and LSM slurries as electrolyte and cathode, respectively. Dense YSZ electrolyte film was successfully prepared on the porous NiO-YSZ anode substrate by tuning pre-sintering temperature of NiO-YSZ and co-firing temperature. The thickness of YSZ film was controlled by the solid content of slurry and coating cycles. The experimental conditions affecting on the thickness of YSZ film was discussed. Single cells with the active electrode area ${\sim}0.8\;cm^2$ were prepared by spin-coating the cathode layers of LSM-YSZ mixture and LSM consequently as well. The effects of the pre-sintering temperature and thus the microstructure of NiO-YSZ substrate on the current-voltage characteristics of co-fired cell were investigated.
EB-PVD법에 의해 제조된 YSZ 전해질의 전기적 특성
신태호,유지행,이시우,한인섭,우상국,현상훈,Shin, Tae-Ho,Yu, Ji-Haeng,Lee, Shiwoo,Han, In-Sub,Woo, Sang-Kuk,Hyun, Sang-Hoon 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.2
나노 코팅 기술로써 빠른 증착 속도와 미세구조 제어가 용이하여 항공기 엔진 부품 열차폐 코팅으로 널리 이용되는 Electron Beam Physical Vapor Deposition (EB-PVD)세라믹 코팅 기술을 연료전지 전해질 제조에 적용하였다. EB-PVD 법을 이용하여 NiO-YSZ 기판에 YSZ 전해질을 약 10$\mu$m의 두께로 짧은 시간에 코팅하였으며 증착온도에 따라 나노 구조의 표면을 가진 YSZ 막을 얻을 수 있었다. 연료전지 전해질로서의 특성을 평가하기 위하여, 같은 조건의 코팅으로 $Al_{2}O_3$기판에 전해질을 동일한 조건으로 코팅하여 전해질의 전기적 특성을 평가하였다. 또한 양극물질로서 $LaSrCoO_3$ 분말을 일반적인 스크린 프린팅 기법으로 코팅하여 EB-PVD의 코팅을 이용한 고체산화물 연료전지 제조 가능성에 대하여 논의하였다 Electron Beam Physical Vapor Deposition (EB-PVD) is a typical technology for thermal barrier coating with Yttria Stabilized Zirconia (YSZ) on aero gas turbine engine. In this study EB-PVD method was used to fabricate dense YSZ film on NiO-YSZ as a electrolyte of Solid Oxide Fuel Cell (SOFC). Dense YSZ films of -10 $\mu$m thickness showed nano surface structure depending on deposition temperature. Electrical conductivities of YSZ film and electric power density of the single cell were evaluated after screen- printing $LaSrCoO_3$ as a cathode.
Dual Phase 전도성 CO<sub>2</sub> 분리막: 메커니즘, 미세구조 및 전기전도도
이시우,유지행,우상국,Lee, Shi-Woo,Yu, Ji-Haeng,Woo, Sang-Kuk 한국세라믹학회 2007 한국세라믹학회지 Vol.44 No.8
Novel conductive $CO_2$ membranes composed of dual phases, molten carbonates and electronic conducting ceramics, were investigated. As the microstructure control of electronic conducting ceramic supports is extremely important to keep the molten carbonates stable in the membranes by a capillary force applied by the pore structure of the supports, we have scrutinized the microstructure of the electronic conducting supports utilizing microscopic images and gas permeability measurement. From the evaluation of the electrical conductivities of the molten carbonates and the electronic conducting ceramic supports, we found that the ionic conductivity of the molten carbonates could determine $CO_2$ flux through the dual phase membranes if the surface exchange rate were relatively high enough.
고온 산소분리막용 고강도 다공성 지지체 제조 및 기계적 특성 연구
박금숙,성영훈,유지행,우상국,한문희,Park, Geum Sook,Seong, Young-Hoon,Yu, Ji Haeng,Woo, Sang Kuk,Han, Moon Hee 한국세라믹학회 2013 한국세라믹학회지 Vol.50 No.6
Porous YSZ ceramics are fabricated using 3 mol% yittria-stabilized zirconia (3YSZ) and NiO with different particlesizes (0.6 and 7 ${\mu}m$). Nickel oxide (NiO) is added to the YSZ powder as a pore former with different amounts(40, 50, and 60 vol%) and at different sintering temperatures (1350 and $1400^{\circ}C$) are applied in order to evaluate the temperature effects on the pore and mechanical properties. Heat treatment is conducted after sintering at $700^{\circ}C$ in $H_2$ for the NiO reduction process; then, Ni is removed using a $HNO_3$ etchant solution. According to the NiO contentand sintering temperatures, 41-67% porous YSZ ceramic is obtained and the flexural strength increases, while the porosity decreases with an increasing sintering temperature. The optimum flexural strength ($136.5{\pm}13.4MPa$) and porosity (47%) for oxygen transport porous YSZ membrane can be obtained with 40 vol% of 7 ${\mu}m$ NiO particle at a sintering temperature of $1350^{\circ}C$.
고상반응에 의하여 제조된 Li<sub>2</sub>ZrO<sub>3</sub>의 이산화탄소 흡수 및 소결 특성
우상국,이시우,유지행,Woo, Sang-Kuk,Lee, Shi-Woo,Yu, Ji-Haeng 한국세라믹학회 2006 한국세라믹학회지 Vol.43 No.5
We synthesized lithium zirconate using solid-state reaction and analyzed thermal properties (TG/DTA) of starting materials and the synthesized one. When $Li_2ZrO_3$ powder was exposed to $CO_2$ environment at $500^{\circ}C$, 93% of the theoretical absorption weight was gained within 280 min with fairly high sorption rate. Almost all the absorbed $CO_2$ was generated by heating the sample to $800^{\circ}C$. We also investigated densification behavior of $Li_2ZrO_3$ under $CO_2$ environment. By sintering $Li_2ZrO_3$ at $760^{\circ}C$ using 2-step process, we obtained dense product, composed mainly of $Li_2ZrO_3\;and\;ZrO_2$, with relative density of 92%.
Li<sub>2</sub>ZrO<sub>3</sub> 분리막의 제조와 이산화탄소 선택투과 전후의 기계적 특성 평가
박상현,이시우,유지행,우상국,이기성,Park, Sang-Hyun,Lee, Shi-Woo,Yu, Ji-Haeng,Woo, Sang-Kuk,Lee, Kee-Sung 한국세라믹학회 2007 한국세라믹학회지 Vol.44 No.1
In this study, we investigated $Li_2ZrO_3$ membrane as a candidate material for high-temperature $CO_2$ separation and evaluated mechanical property. $Li_2ZrO_3$ powder was synthesized by solid state reaction of $Li_2CO_3\;and\;ZrO_2$. Then we fabricated $Li_2ZrO_3$ tape using tape casting method. Dense $Li_2ZrO_3$ membrane prepared by sintering at $1600^{\circ}C$ for 2 h after pressing $Li_2ZrO_3$ tape using lamination machine. Mechanical properties before and after $CO_2$ absorption of fabricated $Li_2ZrO_3$ membrane such as Hertzian indentation, Victors hardness and 3-point bending testing were evaluated.
임경태,이충환,유지행,백동현,백경호,Lim, Kyoung Tae,Lee, Chung Hwan,Yu, Ji Haeng,Peck, Dong-Hyun,Baik, Kyeong Ho 한국세라믹학회 2014 한국세라믹학회지 Vol.51 No.3
$La_{0.8}Sr_{0.2}Ga_{0.8}Mg_{0.2-x}Zn_xO_{2.8}$(LSGMZ, X=0-0.05) was prepared using a solid state reaction method. Two secondary phases ($LaSrGaO_4$ and $LaSrGa_3O_7$) of powders were identified by X-ray diffraction analysis. The relative amount of these secondary phases depended on the calcination conditions (temperature and time) and Zn content. The sintering density of LSGMZ was enhanced by increasing the Zn content and calcination temperature at the low sintering temperatures ($1250-1300^{\circ}C$). The relationship between the sintering density of LSGMZ and the synthesis conditions was discussed considering the phase analysis results.
열광전 발전 적용을 고려한 SiC 다공체 연소기의 연소 및 발광 특성에 관한 기초적 연구
이대근(Dae Keun Lee),유지행(Ji Haeng Yu),안세진(Se Jin Ahn) 한국연소학회 2008 KOSCOSYMPOSIUM논문집 Vol.- No.-
Preliminary study was conducted on the combustion and incandescent characteristics of SiC foam combustor aiming at the application to TPV power generation, the direct conversion of heat to electric energy through photon energy. The combustion in porous media was adopted as the primary technology of TPV combustor due to its potential to make high combustion temperature and self-recuperation of exhaust heat by excess enthalpy combustion and direct and uniform heating of emitter of porous media. Experiments were conducted with varying thermal power and equivalence ratio, and the quantification of incandescence, the measurement of temperature and radiative heat flux and the exhaust gas analysis were performed. As a result, the increase of incandescent region was nearly linear with thermal power but nearly constant with equivalence ratio within given conditions. It was also found that the recuperation of exhaust heat was efficient without any additional heat exchanger and the efficiency of thermal-to-radiation conversion reached 16% beyond our expectations.