• 한국수소및신에너지학회논문집
• /
• 제21권6호
• /
• pp.533-539
• /
• 2010

Ni-YSZ supported button cells were prepared by spray-coating YSZ and screen-printing YSZ-LSM powder as an electrolyte and oxygen electrode on Ni-YSZ cermet disks. In order to identify the polarization loss mechanism in high temperature electrolysis current-voltage characteristics coupled with electrochemical impedance spectroscopy were investigated as a function of temperature, current load, and the humidity. The effects of the different current collectors of platinum and silver for oxygen electrodes were compared. With Ag current collector two polarization losses were distinguished. The high frequency component was attributed to the Ni-YSZ cermet which was less susceptible to temperature variation but increasing in loss with humidity. The lower frequency component was attributed to the LSM electrode. Platinum current collector led to a much lower polarization loss.

• 한국결정성장학회지
• /
• 제21권1호
• /
• pp.21-26
• /
• 2011

Ni-YSZ(Yttria Stabilized Zirconia) composite powders를 glycine nitrate process으로 만들었다. 합성된 분말은 $1300{\sim}1400^{\circ}C$ 4시간 동안 소성하였으며 $1000^{\circ}C$에서 2시간 동안 질소 및 수소 분위기에서 환원 소성하여 Ni-YSZ cermet을 제조하였다. Ni의 부피비를 변화 시켜 각기 그들의 미세구조, 전기전도도, 열팽창 및 강도 특성을 알아보았다. Ni과 YSZ 상 사이에 상호 연결된 균질하게 분포된 다공성 미세구조를 얻을 수 있었다. 기공률, 전기전도도, 열팽창계수 및 곡강도 모두 Ni의 양에 민감하게 영향 받는 것을 알 수 있으며 40 vol%의 Ni를 함유한 Ni-YSZ cermet가 전극재료로 가장 적당하였다. $1350^{\circ}C$에서 소성한 40 vol% Ni-YSZ 시편의 경우 30 %의 기공율, 65.5 Mpa의 강도, 917.4 S/cm의 전기 전도도($1000^{\circ}C$)및 $12.6{\times}10^{-6}^{\circ}C^{-1}$의 열팽창계수($1000^{\circ}C$)를 가져 YSZ 전해질의 음극재료로 가장 적합하였다.

• 한국수소및신에너지학회논문집
• /
• 제15권2호
• /
• pp.98-107
• /
• 2004

Modified Ni/YSZ cermets for high temperature electrolysis were synthesized by dry or wet mechanical alloying methods. The Ni/YSZ composit particle was directly fabricated from the ball milling of Ni and YSZ powder or obtained from the reduction of NiO/YSZ particle after the ball milling of NiO and YSZ. In the case of the NiO/YSZ composite particle, the dry milling increased the average particle size whereas the wet milling decreased the size. The dry milling showed that fine YSZ particles were distributed over large Ni surfaces while Ni and YSZ particles similar in size were well mixed in the wet milling method. These features were the same in the Ni/YSZ composite particle prepared from Ni and YSZ powders. The electrical conductivity of the wet-milled Ni/YSZ cermet showed the highest value of $2{\times}10^2S/cm$ among the specimens and this value was increased to $1.4\times10^4S/cm$ after the sintering at $900^\circ{C}$ for 1 h.

• 한국재료학회지
• /
• 제14권10호
• /
• pp.743-748
• /
• 2004

Modified Ni/YSZ cermets for high temperature electrolysis were synthesized by the direct ball milling of Ni and YSZ powder. The ball milling was carried out in dry process and in ethanol with varying milling time. While the dry-milling decreased the average size from 65 to $80{\mu}m$, the wet-milling decreased the average size down to $10{\mu}m$. In addition, very fine particles less than $0.1{\mu}m$ were observed in the wet-milling condition. The subsequent process of cold-pressing and sintering at $900^{\circ}C$ for 2 h did not affect the particle size of dry-milled powder. The electrical conductivity of the dry-milled Ni/YSZ cermet showed the value of $5{\times}10^{2}\;S/cm$ and this value was increased to $1.4{\times}10^{4}\;S/cm$ after the sintering at $900^{\circ}C$ for 2 h.

• 한국세라믹학회지
• /
• 제45권12호
• /
• pp.807-814
• /
• 2008

The Cu-Ni-YSZ cermet anodes for direct use of methane in solid oxide fuel cells have been fabricated by electroplating Cu into the porous Ni-YSZ cermet anode. The uniform distribution of Cu in the Ni-YSZ anode could be obtained via pulse electroplating in the aqueous solution mixture of $CuSO_4{\cdot}5H_{2}O$ and ${H_2}{SO_4}$ for 30 min with 0.05 A of average applied current. The power density ($0.17\;Wcm^{-2}$) of a single cell with a Cu-Ni-YSZ anode was shown to be slightly lower in methane at $700^{\circ}C$, compared with the power density ($0.28\;Wcm^{-2}$) of a single cell with a Ni-YSZ anode. However, the performance of the Ni-YSZ anode-supported single cell was abruptly degraded over 21 h because of carbon deposition, whereas the Cu-Ni-YSZ anode-supported single cell showed the enhanced durability upto 52 h.

• 한국세라믹학회지
• /
• 제51권4호
• /
• pp.357-361
• /
• 2014

An Ni-Fe/YSZ core-shell structured anode for uniform microstructure and catalytic activity was synthesized. Flat tubular segmented-in-series solid oxide fuel cell-stacks were prepared by decalcomania method using synthesized anode powder. The Ni-Fe/YSZ core-shell anode exhibited better electrical conductivity than a commercially available Ni-YSZ cermet anode. Also power output increased by 1.3 times with a higher open circuit voltage. These results can be attributed to the uniformly distributed Ni particles in the YSZ framework. The impedance spectra of a Ni-Fe/YSZ core-shell anode showed comparable reduced ohmic resistance similar to those of the commercially available Ni-YSZ cermet anodes.

• 한국세라믹학회:학술대회논문집
• /
• 한국세라믹학회 2003년도 춘계총회 및 연구발표회 초록집
• /
• pp.130.2-130
• /
• 2003

• 한국결정성장학회지
• /
• 제20권6호
• /
• pp.289-294
• /
• 2010

SOFC용 Ni-YSZ(Yttria Stabilized Zirconia) composite powders를 glycine nitrate process를 이용하여 만들었다. $ZrO(NO_3)_2{\cdot}2H_2O$, $Y(NO_3)_3{\cdot}6H_2O$, $Ni(NO_3)_2{\cdot}6H_2O$와 glycine을 출발원료로 하였으며 Ni의 부피비를 변화시켜 각기 그들의 소결 및 환원 특성을 알아보았다. Ni과 YSZ 상들이 상호 연결된 균질하게 분포된 다공성 미세구조를 관찰 할 수 있었으며 Ni의 첨가량에 따라 가공률이 민감하게 변화함을 알 수 있었다. 35 vol% 이상의 Ni를 함유한 Ni-YSZ cermet가 SOFC용 전극재료로 사용되는데 필요한 30% 이상의 공극을 갖는 조성임을 알 수 있었다.

• 한국세라믹학회지
• /
• 제43권12호
• /
• pp.764-767
• /
• 2006

Ni/YSZ $(Y_2O_3-stabilized\;ZrO_2)$ composite as an electrode component for High Temperature Electrolysis (HTE) was fabricated by mechanical alloying method using Ni and YSZ powders. Characterization of the synthesized composite was investigated with various analysis tools, including XRD, SEM and PSA, and a self-supporting planar unit cell prepared with the Ni/YSZ composite was prepared to study the electrochemical reactions for the production of hydrogen. The Ni/YSZ cermet is composed of crystalline Ni and YSZ, in a sub-micro scale, and has an even distribution without aggregated particles. In addition, under an electrochemical reaction, the unit cell showed an $H_2$ evolution rate from steam of 14 Nml/min and $600mA/cm^2$ of current density at the electrode.

• 한국분말재료학회지
• /
• 제18권5호
• /
• pp.430-436
• /
• 2011

Joining of NiO-YSZ to 316 stainless steel was carried out with B-Ni2 brazing alloy (3 wt% Fe, 4.5 wt% Si, 3.2 wt% B, 7 wt% Cr, Ni-balance, m.p. 971-$999^{\circ}C$) to seal the NiO-YSZ anode/316 stainless steel interconnect structure in a SOFC. In the present research, interfacial (chemical) reactions during brazing at the NiO-YSZ/316 stainless steel interconnect were enhanced by the two processing methods, a) addition of an electroless nickel plate to NiO-YSZ as a coating or b) deposition of titanium layer onto NiO-YSZ by magnetron plasma sputtering method, with process variables and procedures optimized during the pre-processing. Brazing was performed in a cold-wall vacuum furnace at $1080^{\circ}C$. Post-brazing interfacial morphologies between NiO-YSZ and 316 stainless steel were examined by SEM and EDS methods. The results indicate that B-Ni2 brazing filler alloy was fused fully during brazing and continuous interfacial layer formation depended on the method of pre-coating NiO-YSZ. The inter-diffusion of elements was promoted by titanium-deposition: the diffusion reaction thickness of the interfacial area was reduced to less than 5 ${\mu}m$ compared to 100 ${\mu}m$ for electroless nickel-deposited NiO-YSZ cermet.