• 제목/요약/키워드: Ni dissolution

검색결과 99건 처리시간 0.017초

코발트와 나이오븀이 코팅된 NiO 용융탄산염 연료전지 양극물질 특성 연구 (Characterization of (Co/Nb)-coated NiO as a Cathode Material for Molten Carbonate Fuel Cells)

  • 최희선;이철우;김건
    • 전기화학회지
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    • 제13권3호
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    • pp.203-210
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    • 2010
  • 용융탄산염 연료전지(MCFC)의 양극으로 사용되는 NiO는 $650^{\circ}C$의 용융탄산염과 산소 분위기 조건에서 안정하고 높은 전기 전도도를 가지는 장점이 있다. 그러나, 장시간 운전 시 양극에서 전해질로의 Ni dissolution은 전지 내부의 단락을 초래하여 전지의 수명을 단축시킨다. 본 연구에서는 대체 전극물질로서 코발트와 나이오븀을 코팅시킨 NiO 전극을 제조하였으며, 이렇게 제조된 전극은 기존 NiO전극과 비교하여 낮은 Ni dissolution과 안정되고 우수한 전기화학 성능을 보임을 확인하였다.

용융탄산염형 연료전지의 NiO 공기극의 용해거동에 미치는 알루미나 코팅효과에 대한 연구 (A study on the effect of alumina coating on NiO dissolution in molten carbonate fuel cell)

  • 류보현;윤성필;한종희;남석우;임태훈;홍성안
    • 신재생에너지
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    • 제1권1호
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    • pp.64-71
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    • 2005
  • The stability of alumina-coated NiO cathodes was studied in $Li_{0.62}/K_{0.38}$ molten carbonate electrolyte. Alumina was effectively coated on the porous Ni plate using galvanostatic pulse plating method. The deposition mechanism of alumina was governed by the concentration of hydroixde ions near the working electrode, which was controlled by the temperature of bath solution. Alumina-coated NiO cathodes were formed to $A1_2O_3-NiO$ solid solution by the oxidation process and their Ni solubilities were were than that of NiO up to the immersion time of 100h. However, their Ni solubilities increased and were similar to that of the bare NiO cathode after 100h. It was because aluminum into the solid solution was segregated to $\alpha-LiAlO_2$ on the NiO and its Product did not Play a role of the Physical barrier against NiO dissolution.

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Anodic Dissolution Property and Structure of Passive Films on Equiatomic TiNi Intermetallic Compound

  • Lee, Jeong-Ja;Yang, Won-Seog;Hwang, Woon-Suk
    • Corrosion Science and Technology
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    • 제6권6호
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    • pp.311-315
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    • 2007
  • The anodic polarization behavior of equiatomic TiNi shape memory alloy with pure titanium as a reference material was investigated by means of open circuit potential measurement and potentiodynamic polarization technique. And the structure of passive films on TiNi intermetallic compounds was also conducted using AES and ESCA. While the dissolved Ni(II) ion did not affect the dissolution rate and passivation of TiNi alloy, the dissolved Ti(III) ion was oxidated to Ti(IV) ion on passivated TiNi surface at passivation potential. It has also been found that the Ti(IV) ion increases the steady state potential, and passivates TiNi alloy at a limited concentration of Ti(IV) ion. The analysis by AES showed that passive film of TiNi alloy was composed of titanium oxide and nickel oxide, and the content of titanium was three times higher than that of nickel in outer side of passive film. According to the ESCA analysis, the passive film was composed of $TiO_2$ and NiO. It seems reasonable to suppose that NiO could act as unstabilizer to the oxide film and could be dissolved preferentially. Therefore, nickel oxide contained in the passive film may promote the dissolution of the film, and it could be explained the reason of higher pitting susceptibility of TiNi alloy than pure Ti.

The Enhanced Physico-Chemical and Electrochemical Properties for Surface Modified NiO Cathode for Molten Carbonate Fuel Cells (MCFCs)

  • Choi, Hee Seon;Kim, Keon;Yi, Cheol-Woo
    • Bulletin of the Korean Chemical Society
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    • 제35권5호
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    • pp.1305-1311
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    • 2014
  • The nickel oxide, the most widely used cathode material for the molten carbonate fuel cell (MCFC), has several disadvantages including NiO dissolution, poor mechanical strength, and corrosion phenomena during MCFC operation. The surface modification of NiO with lanthanum maintains the advantages, such as performance and stability, and suppresses the disadvantages of NiO cathode because the modification results in the formation of $LaNiO_3$ phase which has high conductivity, stability, and catalytic activity. As a result, La-modified NiO cathode shows low NiO dissolution, high degree of lithiation, and mechanical strength, and high cell performance and catalytic activity in comparison with the pristine NiO. These enhanced physico-chemical and electrochemical properties and the durability in marine environment allow MCFC to marine application as a auxiliary propulsion system.

Dissolution and Reprecipitation Behavior of TiC-TiN-Ni Cermets During Liquid-Phase Sintering

  • Yoon, Choul-Soo;Shinhoo Kang;Kim, Doh-Yeon
    • The Korean Journal of Ceramics
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    • 제3권2호
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    • pp.124-128
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    • 1997
  • An attempt was made to understand the dissolution and reprecipitation behavior of the constituent phases such as TiC, TiN, and Ti(CN) in TiC-TiN-Ni system. During the liquid-phase sintering the TiC phase was found to dissolve preferentially in Ni binder. The solid-solution phase, Ti(CN), formed around the TiN phase, resulting in a core/rim structure. This result was reproduced when large TiC particles were used with fine TiN particles. The path for the microstructural change in TiC-TiN-Ni system was largely controlled by the difference in the interfacial energy of each phase with the liquid binder phase. The results were discussed with thermodynamic principles.

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Phthalate 완충용액에서 전해 석출한 철족 원소의 산화 용해 반응 (Anodic Dissolution of Electrodeposited Iron Group Elements in Phthalate Buffer Solution)

  • 천정균;김연규
    • 대한화학회지
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    • 제51권1호
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    • pp.14-20
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    • 2007
  • 금(Au) 전극 위에 전해 석출한 철족 원소(Fe, Co, Ni)를 전극으로 phthalate 완충 용액에서 철족 원소의 부식과정을 조사하였다. Phthalate 완충용액의 pH의 변화에 대한 부식전위와 부식전류를 측정하여 각 원소(Fe, Co, Ni)전극의 산화반응과 환원반응에 대한 Tafel 기울기를 구하였으며 Tafel 기울기를 포함한 정량적인 전기화학 인자를 측정하여 전극의 산화반응과 환원반응에 대한 반응 메커니즘을 제안하였다. Phthalate 완충 용액에 존재하는 화학 종의 흡착은 철족 원소 전극의 산화반응에 영향을 미치는 것으로 보인다.

유사 조성의 모재분말과 Ni기 삽입금속 혼합분말을 사용한 천이액상확산 접합 시 모재의 용해현상 (Dissolution Phenomenon of the Base Metal during TLP Bonding Using the Modified Base Metal Powder and Ni Base Filler Metal Powder)

  • 송우영;예창호;강정윤
    • Journal of Welding and Joining
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    • 제25권3호
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    • pp.64-71
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    • 2007
  • The dissolution phenomenon of the solid phase powder and base metal by liquid phase insert metal during Transient Liquid Phase bonding using the mixed powder composed of the modified GTD111(base metal) powder and the GNi3 (Ni-l4Cr-9.5Co-3.5Al-2.5B) powder was investigated. In case of the mixed powder contains modified GTD111 powder 50wt%, all of the powder was melted by liquid phase at 1423K. At the temperature between solidus and liquidus of GNi3, liquid phase penetrated into the boundary of the modified GTD111 powder and solid particle separated from powder was melted easily because area of reaction was increased. With increasing mixing ratio of the modified GTD111, it needed the higher temperature to melt all of the modified GTD111 powder. During Transient Liquid Phase bonding using the mixed powder composed of the modified GTD111 50wt% and GNi3 50wt% as insert metal, width of the bonded interlayer was increased with increasing bonding temperature by reaction of the base metal and liquid phase in insert metal. Dissolution of the base metal and modified powder by liquid phase progressed all together and after all of the powder was melted nearly, the dissolution of the base metal occurred quickly.