Method of forming an interface between components having different rates of expansion

1. A method of forming a thermally cycled component assembly, comprising:

forming a first component including:

determining dimensional characteristics of said first component,

defining an axis of volumetric expansion for said first component,

projecting a sphere having a center on said axis,

defining the center of said sphere as a center of growth of said first component,

projecting a perimeter of said component onto said sphere to define a projection line, and

forming an interface surface of said first component based on a plurality of planes each of which includes said center of growth, a point on said projection line and a tangent to that point on said projection line.

2. The method of claim 1 , further comprising forming a second component having a complimentary interface surface configured to associate with said interface surface.

3. The method of claim 2 , further comprising assembling said first and second components by interfacing said interface surface and said complimentary interface surface to form said assembly.

4. The method of claim 3 , further comprising forming a shear plane between said interface surface and said complimentary interface surface that allows slippage during volumetric cycling of said first and second components.

5. The method of claim 4 , further comprising allowing said shear plane to reduce thermal stress in said first and second components.

6. The method of claim 1 , further comprising forming a plurality of components by:

determining dimensional characteristics of each component,

defining an axis of volumetric expansion for each component,

defining a center of growth for each of said components, and

forming an interface surface for each of said components with respect to the center of growth for that component.

7. The method of claim 6 , wherein said forming an interface surface further comprises:

for each component, locating a sphere of predetermined radius with a center on said axis of volumetric expansion;

locating said sphere along said axis based on a desired location for said interface surface; and

defining the center of said sphere as the center of growth for that component.

8. The method of claim 7 , further comprising:

projecting a perimeter of that component on said sphere to form a projection line; and

forming an interface surface of that component based on a plurality of planes each of which includes the center of growth for that component, a point on the projection line for that component and a tangent to that point on the projection line.

9. The method of claim 8 , further comprising assembling said components.

10. The method of claim 9 , wherein assembling said components further comprises assembling said components such that each of said centers of growth are substantially coincident.

11. The method of claim 6 , wherein said center of growth for each of said components is the same point.

12. The method of claim 6 , wherein said components comprise components used in a thermally cycled device.

13. The method of claim 12 , wherein said thermally cycled device comprises a fuel cell system.

14. The method of claim 6 , wherein said components comprise an electrical pass through assembly.

15. The method of claim 6 , wherein said components comprise a ceramic retention feature assembly.

16. The method of claim 6 , wherein said components comprise an end cell seal assembly.

17. The method of claim 13 , wherein said thermally cycled device comprises a solid oxide fuel cell system.

18. The method of claim 2 , further comprising disposing a seal between said interface surface and complimentary interface surface.

19. The method of claim 18 , wherein said seal comprises a liquid metal seal

20. The method of claim 6 , wherein each of said components have different rates of expansion.