K. S. Weil, Pacific Northwest National Laboratory, Richland, WA; J. S. Hardy, Pacific Northwest National Laborotory, Richland, WA
One of the critical issues in designing and fabricating a high performance planar solid oxide fuel cell (pSOFC) stack is the development of the appropriate materials and techniques for hermetically sealing the metal and ceramic components. There are essentially two standard methods of sealing: (1) by forming a rigid joint or (2) by constructing a compressive “sliding” seal. Each method has its own set of advantages and design constraints. We are currently developing an alternative approach that appears to combine some of the advantages of the other two techiques, including hermeticity, mechanical integrity, and minimization of interfacial stresses in either of the joint substrate materials, particulary the ceramic. The new sealing concept relies on a plastically deformable metal seal; one that offers a quasi-dynamic mechanical response in that it is adherent to both sealing surfaces, i.e. non-sliding, but readily yields or deforms under thermally generated stresses, thereby mitigating the development of stresses in the adjacent ceramic and metal components even when a significant difference in thermal expansion exists between the two materials.
Summary: One of the critical issues in designing and fabricating a high performance planar solid oxide fuel cell (pSOFC) stack is the development of the appropriate materials and techniques for hermetically sealing the metal and ceramic components. There are essentially two standard methods of sealing: (1) by forming a rigid joint or (2) by constructing a compressive “sliding” seal. Each method has its own set of advantages and design constraints. We are currently developing an alternative approach that appears to combine some of the advantages of the other two techiques, including hermeticity, mechanical integrity, and minimization of interfacial stresses in either of the joint substrate materials, particulary the ceramic. The new sealing concept relies on a plastically deformable metal seal; one that offers a quasi-dynamic mechanical response in that it is adherent to both sealing surfaces, i.e. non-sliding, but readily yields or deforms under thermally generated stresses, thereby mitigating the development of stresses in the adjacent ceramic and metal components even when a significant difference in thermal expansion exists between the two materials.
