抄録
The molten carbonate fuel cell (MCFC) which possesses a high conversion efficiency, is expected to be a future energy conversion device. However, the MCFC operates at a high temperature, and therefore, the battery materials corrode. This has been a serious problem in realizing the high-performance of the MCFC. In this study, the corrosion behavior of Fe metal and Fe-Ni alloy, which are used as separators, in 46mol% Li2CO3-54mol% Na2CO3 (46/54melt), 52mol% Li2CO3-48mol% Na2CO3 (52/48melt), and 58mol% Li2CO3-42mol% Na2CO3 (58/42melt) systems have been focused on. From the results of the SEM observation and XRD measurement, the corrosion of Fe metal was restrained effectively in the 52/48melt. LiFeO2, which made the substrate surface stronger against corrosion, was formed densely on the surface of substrates immersed in the 52/48melt. On the other hand, when the substrates were immersed in the other melts, LiFeO2 did not exist on the surface. LiFe5O8, which could not make the substrate surface stronger against corrosion, existed on the surface and the layer was formed coarsely. Moreover, the Fe-Ni alloy substrate restrained the spreading of corrosion compared to the Fe metal substrate. GD-OES depth profiles of Fe-Ni alloy indicated that the Ni metal layer, which is formed in the corrosion surface layer, suppressed the spreading of corrosion. The corrosion of Fe-Ni was also restrained effectively in the 52/48melt. It is considered that the double layer of LiFeO2 and Ni metal effectively inhibited the spreading of corrosion on Fe-Ni alloy.
