용융탄산염 연료전지(MCFC)용 anode 재질로써 촉매 성능면이나 가격면에서 가장 적합한 것은 Ni이나, 순수한 Ni만으로 제조된 anode는 고온에서 크립(creep) 현상이 커서 이의 해결책이 강구되어져야만 한다. 본 연구에서는 이 크립 현상을 감소시키기 위한 한 방법으로 pack cementation 기법을 이용하여 다공성 Ni-anode 소재에 Ni-Al, Ni-Cr, Ni-Al-Cr등의 합금 형태(금속간 화합물 또는 고용체)가 되도록 처리한 후 해당 재질들의 크립 특성을 검토하였다. 이때 팩(pack) 성분은 증착시키려는 금속 분말과 활성제(NaCl, NH ₄Cl), 그리고 비활성 충전물(Al₂O₃)로 구성되었고 온도는 550-900℃의 범위에서 0.5-5시간 동안 반응시켰다. 다공성 Ni소재에 해당 금속의 증착량은 반응 시간의 제곱근에 비례하는 형태를 나타내었으며 증착량이 증가할수록 다공성 Ni 소재 anode의 기공도는 선형으로 감소하였다. 순수한 Ni소재 anode에 비하여 합금 형태 anode는 크립 현상이 크게 감소함을 보였고 특히 Al과 Cr이 동시에 증착된 합금 전극의 수축률이 가장 낮은 1-2 %의 값을 보였다.

The Pack cementation process of metal(Al, Cr) halide vapor on a porous pure Ni-anode substrate fur molten carbonate fuel cell was studied to improve creep resistance of the anode substrate. The pack consists of metal powder(Al, Cr or Al-Cr mixture), activator(NaCl or NH₄Cl) and inert filler(Al₂O ₃). The pack cementations on the nickel-anode substrate were carried out at 550-900℃ for 0.5-5.0 hours. It was found that various intermetallic compounds for Al(Ni₃Al, NiAl, or Ni₂A1₃) and some of solid solution between Ni and Cr were formed on the porous Ni-anode substrate and the deposition weight of metals depending on time was parabolic. The porosity of the alloy anodes(intermetallic or solid solution) decreases linearly with deposition content of metallic additives. The Ni-anodes deposited as Ni-Al intermetallic form and codeposited with Al and Cr showed good performance against creep and its pore structure did not change after pack cementation. The Ni-anode substrate, which Al and Cr were codeposited on, showed about 1% creep strain under 650℃ and 100 psi after 100 hour.

MCFC Alloy Anode Creep Pack Cementation Intermetallic Compound Solid Solution

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