Turbomachine shroud

1. A turbomachine comprising:

a cylindrical shroud assembly having an inner surface and an outer surface;

wherein said inner surface comprises a roughed ceramic surface for contacting a rotating turbomachine component;

said roughed ceramic surface comprises a plurality of raised portions protruding radially inward from said inner shroud surface toward an axis defined by said shroud assembly, said raised portions are arranged in a random arrangement across said roughed ceramic surface; and

wherein said plurality of raised portions and said cylindrical shroud assembly are a monolithic ceramic piece.

2. The turbomachine of claim 1 , wherein said roughed ceramic surface comprises a ceramic coating.

3. The turbomachine of claim 1 , wherein said roughed ceramic surface and said plurality of raised portions are comprised of a single material.

4. The turbomachine of claim 1 , wherein each of said raised portions comprises at least one cutting edge, for abrading a rotating turbomachine component.

5. The turbomachine of claim 4 , wherein each of said cutting edges comprises a self sharpening ceramic edge.

6. The turbomachine of claim 4 , wherein said cutting edge is defined by a joint between an axially facing surface of one of said raised portions and a radially facing surface of said one of said raised portions.

7. The turbomachine of claim 6 , wherein said raised portions interface with said rotating turbomachine component at said radially facing surface.

8. The turbomachine of claim 4 , wherein each of said raised portions comprises a rise separated from at least one adjacent rise via a groove.

9. The turbomachine of claim 8 , wherein each of said rises is approximately parallel to an axis defined by said shroud assembly.

10. The turbomachine of claim 8 , wherein each of said rises is at an angle to an axis defined by said shroud assembly, and is aligned with each other rise.

11. The turbomachine of claim 8 , wherein each of said rises comprises two cutting edges.

12. A shroud for use with a turbomachine comprising:

a cylindrical shroud having a radially outer surface and a radially inner surface;

wherein said radially inner surface comprises a plurality of raised elements protruding radially inward from an inner shroud surface toward an axis defined by the ceramic shroud;

wherein said plurality of raised elements are arranged about the inner surface randomly; and

wherein said roughed ceramic surface, said plurality of raised portions, and said cylindrical shroud are a monolithic ceramic piece.

13. The shroud of claim 12 , wherein each of said raised elements comprises at least one cutting edge.

14. The shroud of claim 12 , wherein said at least one cutting edge is defined by a joint between a radially facing surface of one of said raised elements and an axially facing surface of said one of said raised elements.

15. The shroud of claim 12 , wherein said cutting edge comprises a self sharpening cutting edge.

16. The shroud of claim 12 , wherein each of said plurality of raised elements is separated from each other of said plurality of raised elements via a contiguous valley.

17. The shroud of claim 12 , wherein said radially inner surface comprises a ceramic coating.

18. The shroud of claim 12 , wherein said shroud is a ceramic shroud.

19. The shroud of claim 12 , wherein said roughed ceramic surface and said plurality of raised portions are comprised of a single material.

20. The shroud of claim 12 , wherein each of said raised elements is isolated from at least one adjacent raised element via a groove.

21. The shroud of claim 20 , wherein each of said raised elements is at least partially aligned with each other of said raised elements.

22. A method for reducing thermal generation during a rub event between a shroud assembly and a rotating component, comprising:

establishing a roughed inner surface of said shroud assembly, said roughed inner surface comprising a plurality of raised portions protruding radially inward from said inner shroud surface toward an axis defined by said shroud assembly;

wherein said plurality of raised elements are arranged about the inner surface randomly; and

wherein said roughed ceramic surface, said plurality of raised portions, and said shroud are a monolithic ceramic piece.

23. The method of claim 22 , wherein said plurality of raised portions abrade a rotating component during a rub event.

24. The method of claim 22 , wherein said roughed ceramic surface and said plurality of raised portions are comprised of a single material.