Article with cooling holes and method of forming the same
A method of making an ceramic article according to an exemplary embodiment of this disclosure, among other possible things includes arranging fiber plies into a preform, inserting one or more sacrificial springs to the preform, infiltrating the preform with a matrix material to form an article, and thermally degrading the one or more sacrificial springs to form cooling holes. A ceramic article and a gas turbine engine component are also disclosed.
1. A method of making a ceramic article, comprising:
arranging fiber plies to form a preform;
after forming the preform, inserting one or more sacrificial springs to the preform;
infiltrating the preform with a matrix material to form an article; and
thermally degrading the one or more sacrificial springs to form cooling holes.
2. The method of claim 1 , wherein the one or more sacrificial springs comprise graphite fibers in an epoxy matrix.
3. The method of claim 2 , wherein the epoxy matrix has a carbon yield of between about 30-50 wt. % upon thermal degradation.
4. The method of claim 1 , wherein the one or more sacrificial springs are inserted by being screwed into the preform.
5. The method of claim 1 , wherein the one or more sacrificial springs are inserted such that an axis of the one or more sacrificial springs is perpendicular to a plane of the fiber plies.
6. The method of claim 1 , wherein the one or more sacrificial springs displace fibers in the plies during insertion.
7. The method of claim 1 , wherein the one or more sacrificial springs are inserted through an entire thickness of the preform such that the one or more sacrificial springs meet or extend through opposed faces of the preform.
8. The method of claim 1 , wherein the infiltrating is by chemical vapor infiltration.
9. The method of claim 8 , wherein non-carbon elements of the one or more sacrificial springs vaporize during the infiltration.
10. The method of claim 1 , further comprising providing a sacrificial sheet in the preform prior to inserting the one or more sacrificial springs into the preform, and thermally degrading the sacrificial sheet after the infiltration to form a gap.
11. The method of claim 10 , wherein the step of thermally degrading the sacrificial sheet is simultaneous with the step of thermally degrading the sacrificial sheet.
12. The method of claim 1 , further comprising compressing the preform prior to the infiltration.
13. The method of claim 12 , wherein a fiber content of the preform before compressing is between about 5-20 vol. % and the fiber content of the preform after the compressing is between about 20-50 vol. %.
14. The method of claim 1 , further comprising:
inserting carbon inserts into the cooling holes at a face of the article;
applying a coating to the face; and
thermally degrading the carbon inserts.
15. The method of claim 1 , further comprising forming the one or more sacrificial springs by pultrusion.
16. The method of claim 1 , wherein prior to step of arranging the plies to form the preform, applying an interface coating to one or more of the plies.
17. The method of claim 1 , wherein at least one of the one or more sacrificial springs include a sharpened end configured to facilitate insertion of the at least one sacrificial spring into the preform.
18. The method of claim 1 , further comprising the step of forming the one or more sacrificial springs by:
providing a rod; and
forming the rod into a helical shape.
19. The method of claim 18 , wherein the rod has a diameter between about 0.38 and 1.02 mm (0.015 and 0.040 inches).
20. The method of claim 10 , wherein the sacrificial sheet is arranged with the fiber plies while forming the preform.