Expansion on reduction of calcium doped lanthanum chromite
- Riso National Lab., Roskilde (Denmark). Materials Dept.
Doped lanthanum chromites have been considered as interconnect materials for the solid oxide fuel cell (SOFC) because of their favorable chemical and electrical properties under both oxidizing and reducing environments. Several investigators have studied the materials properties of the doped lanthanum chromites to optimize their overall performance as an interconnect material. These properties include electrical conductivity, thermal expansion, sinterability, and chemical compatibility with other cell components. These properties are optimized by the amount of dopants substituted into chromite which are usually Ca or Sr. Figure 1 shows the range of values for these properties. Another important characteristic becoming more of a concern as investigators are building SOFC stacks is that doped lanthanum chromite expands when reduced in a low oxygen partial pressure (pO{sub 2}) (<10{sup -12} atm). Plates used to separate oxidizing and fuel gases can deform because of the pO{sub 2} gradient across the interconnect material. This presentation is a summary of work which will be presented at the Fourth International Symposium on Solid Oxide Fuel Cells. In this article, the possible causes of expansion on reduction of the interconnect will be discussed by using a two-dimensional crystal model. The biaxial strain of the stack is calculated under the assumption that the cell components are forced to remain planar. From this, the maximum stress buildup in the interconnect and electrolyte is estimated. In addition, the effects of thermal expansion mismatch and expansion on reduction of the interconnect are compared, and the optimum interconnect composition from a mechanical standpoint is reported.
- Research Organization:
- Argonne National Lab., IL (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 90710
- Report Number(s):
- ANL/CMT/CP--85697; CONF-9504191--1; ON: DE95013677
- Country of Publication:
- United States
- Language:
- English
Similar Records
Development of Ceramic Interconnect Materials for SOFC
Mechanical properties of lanthanum and yttrium chromites