Introduction

In the planar SOFC, the interconnect materials plays two roles as an electrical connection and as a gas separation plate in a cell stack. The interconnect materials must be chemically stable in reducing and oxidizing environments, and have high electronic conductivity, high thermal conductivity, matching thermal expansion with an electrolyte, high mechanical strength, good fabricability, and gas tightness(l). Lanthanum chromite so far has been mainly used as interconnect materials in planar SOFC(l,2). However, the ceramic materials are very weak in mechanical strength and have poor machining property as compared with metal. Also the metallic materials have high electronic conductivity and high thermal conductivity.

Recently some researchers have studied metallic interconnects such as AkOj/Inconel 600 cermet(3), Ni-20Cr coated with (LaSr)Co03(4), and Y203- or La203-dispersed Cr alloy(5). These alloys have still some problems because Ni-based alloys have high thermal expansion, the added A1203, Y203 and La203 to metals have no electronic conductivity, and the oxide formed on the surface of Cr alloy has high volatility. To solve these problems, in this study, LaCr03-dispersed Cr for metallic interconnect of planar SOFC was investigated. The LaCr03-dispersed Cr can be one candidate of metallic interconnect because LaCr03 possesses electronic conductivity and Cr metal has relatively low thermal expansion. The content of 25 vol.% LaCr03 was selected on the basis of a theoretically calculated thermal expansion. The thermal expansion, electrical and oxidation properties were examined and the results were discussed as related to SOFC requirements.

0 0

Post a comment