Influence of aluminum depletion on the lifetime of an Al-Fe coating in eutectic (Li,K)(2)CO3 at 650 degrees C

Abstract

The purpose of this study is to evaluate the lifetime of an Al-Fe coating that has been applied to separators of molten carbonate fuel cells (MCFC). In order for the Al-Fe coating to maintain its protective function for the durability requirement of 4 x 10(4) h, it needs to contain enough aluminum to form a protective LiAlO2, layer. If, however, aluminum content in the Al-Fe coating is reduced to a critical le et where the protective LiAlO2 layer is not stable. it can be interpreted that the Al-Fe coating loses its protective function and reaches the lifetime of the coating. The aluminum content in an Al-Fe coating can be depleted by two different processes one is by corrosion reaction at the surface between the aluminum source in the coating and molten carbonate, and the other is inward-diffusion of aluminum atoms within the coating into a substrate. In these two respects, therefore. the decreasing rate of aluminum concentration in an Al-Fe coating was measured, and then the impacts of these two conditions on the Al-Fe coating's lifetime where investigated, respectively.