Internal cooling circuits for CMC and method of manufacture
A method for forming a ceramic matrix composite (CMC) component with an internal cooling channel includes partially densifying a first fiber preform to form a portion of a final ceramic matrix volume, machining a first channel into a surface of the partially densified first fiber preform, covering the first channel with a fibrous member to form a near net shape fiber preform with an internal passage formed by the first channel and the fibrous member, and densifying the near net shape fiber preform.
1. A method for forming a ceramic matrix composite (CMC) component with an internal cooling channel, the method comprising:
partially densifying a first fiber preform to form a portion of a final ceramic matrix volume;
machining a first channel into a surface of the partially densified first fiber preform;
covering the first channel with a fibrous member to form a near net shape fiber preform with an open internal passage formed by the first channel and the fibrous member; and
densifying the near net shape fiber preform with the open internal passage to form the final ceramic matrix volume.
2. The method of claim 1 , wherein the fibrous member comprises a braided fiber tube and wherein covering the first channel with the fibrous member comprises inserting the partially densified first fiber preform into the braided fiber tube.
3. The method of claim 1 , wherein the fibrous member comprises a fiber ply and wherein covering the first channel with the fibrous member comprises wrapping the fiber ply around the partially densified first fiber preform and joining ends of the fiber ply at an overlap joint.
4. The method of claim 1 , wherein the fibrous member is a partially densified second fiber preform.
5. The method of claim 4 , wherein the partially densified second fiber preform has a second channel formed in a surface of the partially densified second fiber preform.
6. The method of claim 5 , wherein the first channel opens to the second channel.
7. The method of claim 1 , wherein machining the first channel comprises forming heat transfer features on a channel surface, wherein the heat transfer features protrude into the internal cooling channel.
8. The method of claim 1 , and further comprising:
applying an interface coating to the first fiber preform before partially densifying the first fiber preform; and
applying an interface coating to the fibrous member before densifying the near net shape preform.
9. The method of claim 1 , wherein the first fiber preform is a three-dimensional woven fiber preform.
10. The method of claim 1 , wherein partially densifying the first fiber preform comprises forming a partially densified fiber preform having a total volume fraction of fiber plus ceramic matrix ranging from 50 to 70 percent.
11. The method of claim 10 , wherein an amount of densification provided in partially densifying the first fiber preform is positively correlated with a thickness of the fibrous member covering the first channel, with densification increasing with thickness.
12. The method of claim 10 , wherein the first channel is sized to accommodate formation of a layer of matrix material during densification of the near net shape fiber preform, the matrix material layer having a height ranging from 10 to 550 microns.
13. A method for forming a ceramic matrix composite (CMC) component with an internal cooling channel, the method comprising:
partially densifying a first fiber preform and a second fiber preform to form a portion of a final ceramic matrix volume;
machining a first channel into a surface of the partially densified first fiber preform;
covering the first channel with a fibrous member to form a near net shape fiber preform with an open internal passage formed by the first channel and the fibrous member; and
densifying the near net shape fiber preform with the open internal passage to form the final ceramic matrix volume.
14. The method of claim 13 , and further comprising:
machining a second channel into a surface of the partially densified second fiber preform;
joining the partially densified first fiber preform to the partially densified second fiber preform at a preform joint; and
covering the second channel with the fibrous member.
15. The method of claim 14 , wherein the fibrous member comprises a braided fiber tube and wherein the joined and partially densified first and second fiber preforms are inserted into the braided fiber tube to cover the first and second channels.
16. The method of claim 14 , wherein the fibrous member comprises a fiber ply and wherein the fiber ply is wrapped around the partially densified first fiber preform and the partially densified second fiber preform to cover the first and second channels and wherein ends of the fiber ply are joined at an overlap joint.
17. The method of claim 14 , and further comprising machining grooves into the partially densified first fiber preform at the preform joint.
18. The method of claim 17 , wherein the grooves are sized and arranged to receive fibers of the partially densified second fiber preform such that fibers nest in the grooves to create a mechanical lock.
19. The method of claim 14 , wherein partially densifying the first fiber preform and partially densifying the second fiber preform comprises forming first and second partially densified fiber preforms each having a total volume fraction of fiber plus ceramic matrix ranging from 50 to 70 percent.
20. The method of claim 19 , wherein an amount of densification provided in partially densifying the first fiber preform and the second fiber preform is positively correlated with a thickness of the fibrous member covering the first and second channels, with densification increased with thickness.