To establish high performance of MCFC, a new high corrosion resistant alloy (30%Cr-45%Ni-l%Al-0.03%Y-Fe) for MCFC separator has been developed"2™1. The developed alloy has good corrosion resistance for both anode and cathode environments. On the other hand, one of the main factors to determine the life time of MCFC stack is electrolyte loss. A potential danger of electrolyte loss cased by corrosion of metal components is pointed out." Basic mechanism of electrolyte loss is proposed according to following reactions.

Fc + Li+ + 2C032 ~ = LiFc00 + 2CO-, + 4c~ Cr + K+ + 4C032 " - K2Cr04 + 4C0o + 8e~

High Cr content alloy, such as type 310S(25%Cr-20%Ni) has disadvantages in view of electrolyte loss in spite of high corrosion resistance5. It is said that the dissolution of Cr ion into electrolyte is. detrimental for electrolyte loss, because a.mole of Cr042" ion combines 2 moles of K4, ions as K,Cr04, while a mole of Fe3+ ion combine a mole of Li+ ion as LiFe02. To understand the mechanism of electrolyte loss due to corrosion of metal component, the distribution of metal ions in oxide and molten salt were studied.

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