• 한국결정성장학회지
• /
• 제25권3호
• /
• pp.116-120
• /
• 2015

혼합이온 전도체인 $K_2NiF_4$-type 산화물인 $La(Ca)_2Ni(Cu)O_{4+{\delta}}$ 분말을 합성하여 결정구조 분석과 분말의 나노구조화에 따른 고체산화물 연료전지의 양극 성능을 비교 평가하였다. 이온 반경이 큰 Cu가 Ni 자리에 치환되어 Ni-O 팔면체 구조에서 c 축 방향으로 결정구조가 팽창하였으며, Ni-Cu의 Jahn-Teller 뒤틀림으로 산소이온 산화 환원 반응과 이온 전도도 특성에 영향을 주었다. 특히 나노구조의 $La(Ca)_2Ni(Cu)O_{4+{\delta}}$ 분말의 경우 표면 촉매성능이 향상되어 단위 전지 성능 향상 결과를 얻을 수 있었다. Ni-YSZ 음극 지지체에 8YSZ 전해질을 dip-coating한 후 $La(Ca)_2Ni(Cu)O_{4+{\delta}}$ 분말을 양극으로 도포하여 얻은 SOFC 단위성능 측정 결과 $800^{\circ}C$에서 $1w/cm^2$의 최대 출력 값을 얻을 수 있었다.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
• /
• pp.136.1-136.1
• /
• 2010

고체산화물 연료전지(SOFC)에서 사용되는 연결재의 주 기능은 각 단위 셀의 연료극과 다음 셀의 공기극을 전기적으로 연결하여, 공기와 사용연료의 분리역할을 하기위해 사용된다. SOFC용 연결재는 다른 구성요소 소재보다 높은 전기전도성, 낮은 이온전도성이 요구되며 SOFC는 고온에서 작동되기 때문에 다른 구성 소재들과 유사한 열팽창계수와 물리, 화학적인 안정성이 요구된다. 현재 연결재 제조기술은 plasma coating, sputtering, screen printing, 전사법등 다양한 연구가 진행되고 있다. 본 연구에서는 저렴한 비용으로 대량생산이 용이한 고상반응법을 적용하여 세라믹연결재를 제조하고, 그 특성을 연구하였다. 세라믹 연결재로서 선정한 합성조성은 $(La_{0.7}Ca_{0.3})(Cr_{0.9}Co_{0.1})O_3$로 SOFC 작동온도에서 높은 전기전도도를 나타낸다. LCCO 연결재를 1300, 1400 및 $1500^{\circ}C$에서 합성을 진행하였을 때 출발원료로 $CaCO_3$를 $CaF_2$로 대체하였을 때의 소결특성을 평가하였고, SEM과 XRD분석을 통하여 균질하고 결정성이 우수한 분말이 합성된 것을 확인하였고 DC impedance analyzer를 사용하여 전기전도도를 측정하였다. TMA를 사용하여 열팽창계수를 측정한 결과 YSZ(${\sim}10.8{\times}10^{-6}/^{\circ}C$)와 동일한 값을 나타내었다.

• 한국분말재료학회지
• /
• 제22권6호
• /
• pp.413-419
• /
• 2015

Lanthanum zirconate, $La_2Zr_2O_7$, is one of the most promising candidates for next-generation thermal barrier coating (TBC) applications in high efficient gas turbines due to its low thermal conductivity and chemical stability at high temperature. In this study, bulk specimens and thermal barrier coatings are fabricated via a variety of sintering processes as well as suspension plasma spray in lanthanum zirconates with reduced rare-earth contents. The phase formation, microstructure, and thermo-physical properties of these oxide ceramics and coatings are examined. In particular, lanthanum zirconates with reduced rare-earth contents in a $La_2Zr_2O_7-4YSZ$ composite system exhibit a single phase of fluorite or pyrochlore after fabricated by suspension plasma spray or spark plasma sintering. The potential of lanthanum zirconate ceramics for TBC applications is also discussed.

• 한국재료학회지
• /
• 제22권11호
• /
• pp.626-630
• /
• 2012

The properties of SOFC unit cells manufactured using the decalcomania method were investigated. SOFC unit cell manufacturing using the decalcomania method is a very simple process. In order to minimize the ohmic loss of flattened tube type anode supports of solid oxide fuel cells(SOFC), the cells were fabricated by producing an anode function layer, YSZ electrolyte, LSM electrode, etc., on the supports and laminating them. The influence of these materials on the power output characteristics was studied when laminating the components and laminating the anode function layer between the anode and the electrolyte to improve the output characteristics. Regarding the performance of the SOFC unit cell, the output was 246 $mW/cm^2$ at a temperature of $800^{\circ}C$ in the case of not laminating the anode function layer; however, this value was improved by a factor of two to 574 $mW/cm^2$ due to the decrease of the ohmic resistance and polarization resistance of the cell in the case of laminating the anode function layer. The outputs appeared to be as high as 574 and 246 $mW/cm^2$ at a temperature of $800^{\circ}C$ in the case of using decalcomania paper when laminating the electrolyte layer using the in dip-coating method; however, the reason for this is that interfacial adhesion was improved due to the dense structure, which leads to a thin thickness of the electrolyte layer.

• 한국표면공학회지
• /
• 제50권2호
• /
• pp.98-107
• /
• 2017

Pd-based membranes have been widely used in hydrogen purification and separation due to their high hydrogen diffusivity and infinite selectivity. However, it has been difficult to fabricate thin and dense Pd-based membranes on a porous stainless steel(PSS) support. In case of a conventional PSS support having the large size of surface pores, it was required to use complex surface treatment and thick Pd coating more than $6{\mu}m$ on the PSS was required in order to form pore free surface. In this study, we could fabricate thin and dense Pd membrane with only $3{\mu}m$ Pd layer on a new PSS support manufactured by metal injection molding(MIM). The PSS support had low surface roughness and mean pore size of $5{\mu}m$. Pd membrane were prepared by advanced Pd sputter deposition on the modified PSS support using fine polishing and YSZ vacuum filling surface treatment. At temperature $400^{\circ}C$ and transmembrane pressure difference of 1 bar, hydrogen flux and selectivity of $H_2/N_2$ were $11.22ml\;cm^{-2}min^{-1}$ and infinity, respectively. Comparing with $6{\mu}m$ Pd membrane, $3{\mu}m$ Pd membrane showed 2.5 times higher hydrogen flux which could be due to the decreased Pd layer thickness from $6{\mu}m$ to $3{\mu}m$ and an increased porosity. It was also found that pressure exponent was changed from 0.5 on $6{\mu}m$ Pd membrane to 0.8 on $3{\mu}m$ Pd membrane.

• 대한금속재료학회지
• /
• 제46권10호
• /
• pp.646-651
• /
• 2008

The electrolytic reduction of spent oxide fuel involves the liberation of oxygen in a molten LiCl electrolyte, which results in a chemically aggressive environment that is too corrosive for typical structural materials. It is essential to choose the optimum material for the process equipment handling molten salt. IN713LC is one of the candidate materials proposed for application in electrolytic reduction process. In this study, yttria-stabilized zirconia (YSZ) top coat was applied to a surface of IN713LC with an aluminized metallic bond coat by an optimized plasma spray process, and were investigated the corrosion behavior at $675^{\circ}C$ for 216 hours in the molten salt $LiCl-Li_2O$ under an oxidizing atmosphere. The as-coated and tested specimens were examined by OM, SEM/EDS and XRD, respectively. The bare superalloy reveals obvious weight loss, and the corrosion layer formed on the surface of the bare superalloy was spalled due to the rapid scale growth and thermal stress. The top coatings showed a much better hot-corrosion resistance in the presence of $LiCl-Li_2O$ molten salt when compared to those of the uncoated superalloy and the aluminized bond coatings. These coatings have been found to be beneficial for increasing to the hot-corrosion resistance of the structural materials for handling high temperature lithium molten salts.