Slurry infiltration heat treatment method

Patent metadata

Field	Value
Publication number	US-12054438-B2
Application number	US-202017006191-A
Country	US
Kind code	B2
Filing date	Aug 28, 2020
Priority date	Nov 25, 2019
Publication date	Aug 6, 2024
Grant date	Aug 6, 2024

Abstract

A method of producing a melt infiltrated ceramic matrix composite (CMC) article that includes the steps of: forming a ceramic fiber preform; optionally, rigidizing the ceramic fiber preform with a fiber interphase coating via a Chemical Vapor Infiltration (CVI) process, infiltrating a ceramic slurry into the porous body or preform, conducting one or more secondary operations, and finally, melt infiltrating the preform with molten silicon or a silicon alloy to form the CMC article. The infiltration of a ceramic slurry into a ceramic fiber preform to form a green body is performed along with the use of convection and/or conduction as heat transfer mechanisms, such that the ceramic slurry does not require the incorporation of a pre-gelation material in order for the slurry to remain within the green body during subsequent processing steps.

First claim

What is claimed is:

1. A method of producing a ceramic matrix composite (CMC) article, the method comprising steps of:
forming a fiber preform;
transforming the fiber preform into a green body; the transformation process comprising:
placing the fiber preform inside a pliable container having an internal volume and an external surface; and
infiltrating a ceramic slurry comprising solid particulate fillers and a solvent into the fiber preform to form a wet infiltrated preform, the solvent consisting of water or isopropanol, the ceramic slurry not including a gellation polymer;

drying the wet infiltrated preform to form the green body; wherein drying the wet infiltrated preform comprises:
creating a pressure differential between the internal volume and the external surface of the pliable container, such that the ceramic slurry remains within the wet infiltrated fiber preform;
placing the pliable container and the wet infiltrated preform into a fluid bath at ambient temperature;
heating the fluid bath to a predetermined hold temperature;
maintaining the fluid bath at the hold temperature for a predetermined time period, wherein the heat from the fluid bath is transferred to the wet infiltrated preform at least partially by conduction, such that the wet infiltrated preform is transformed into the green body;
removing the pliable container from the fluid bath; and
removing the green body from the pliable container; and

infiltrating the green body with a molten silicon or silicon alloy to form the CMC article.

2. The method according to claim 1 , wherein the ceramic slurry consists of the solid particulate fillers, one or more reactive additive, the solvent, and one or more dispersants or binders.

3. The method according to claim 2 , wherein the one or more reactive additives includes at least one of graphite, diamond, carbon black, molybdenum (Mo), and tungsten (W).

4. The method according to claim 1 , wherein the solid particulate fillers comprise silicon carbide (SIC), silicon nitride (Si 3 N 4 ), or a mixture thereof.

5. The method according to claim 1 , wherein the ceramic slurry infiltrated into the fiber preform comprises a solid loading in the range of about 10 vol. % to about 70 vol. % relative to the overall volume of the ceramic slurry.

6. The method according to claim 1 , further comprising, prior to transforming the fiber preform into a green body, rigidizing the fiber preform with a fiber interphase coating,
wherein rigidizing the fiber preform with the fiber interphase coating uses a chemical vapor infiltration (CVI) process.

7. The method according to claim 6 , wherein the fiber interphase coating comprises silicon carbide (SiC), silicon nitride (Si 3 N 4 ), or a mixture thereof.

8. The method according to claim 1 , wherein the fiber preform comprises silicon carbide (SiC), silicon nitride (Si 3 N 4 ), or a mixture thereof.

9. The method of claim 1 , wherein the heating of the fluid bath comprises heating at a rate that ranges from about 0.5° C./min to about 2° C./min.

10. The method according to claim 9 , wherein the predetermined hold temperature is reached in about 50 minutes.

11. The method of according to claim 1 , wherein the temperature difference between the fluid bath and the ceramic slurry in the wet infiltrated preform is less than 3° C.

12. The method according to claim 10 , wherein the predetermined hold temperature is in the range from about 30° C. to about 80° C.

13. The method according to claim 12 , wherein the hold temperature is maintained for the predetermined time period that ranges from about 5 minutes to about 24 hours.

14. The method according to claim 1 , wherein the fluid bath is a heated bath circulator, such that heat transfer from the fluid bath to the ceramic slurry in the wet infiltrated preform is uniformly distributed.

15. The method according to claim 1 , wherein the fiber preform comprises fibers that include one or more of silicon carbide (SiC), silicon nitride (Si 3 N 4 ), or a mixture thereof;
wherein, prior to placing the fiber preform inside the pliable container, the fiber preform is rigidized via a chemical vapor infiltration (CVI) process with a fiber interphase coating comprising silicon carbide (SIC), silicon nitride (Si 3 N 4 ), or a mixture thereof.

16. The method according to claim 1 , wherein the heating of the fluid bath comprises heating at a rate that ranges from about 0.5° C./min to about 2° C./min;
wherein the temperature difference between the fluid bath and the ceramic slurry in the wet infiltrated preform is less than 3° C.

17. The method according to claim 16 , wherein the predetermined hold temperature is reached in about 50 minutes;
wherein the hold temperature is maintained for the predetermined time period that ranges from about 5 minutes to about 24 hours.

18. A method of forming a green body for use in making a ceramic matrix composite (CMC) article; the method comprising:
placing a fiber preform inside a pliable container having an internal volume and an external surface;
infiltrating a ceramic slurry into the fiber preform to form a wet infiltrated preform, the ceramic slurry comprising solid particulate fillers and a solvent, the solvent consisting of water or isopropanol, the ceramic slurry not including a gellation polymer; and
drying the wet infiltrated preform to form the green body; wherein drying the wet infiltrated preform comprises:
creating a pressure differential between the internal volume and the external surface of the pliable container, such that the ceramic slurry remains within the wet infiltrated fiber preform;
placing the pliable container and the wet infiltrated preform into a fluid bath at ambient temperature;
heating the fluid bath to a predetermined hold temperature; wherein the predetermined hold temperature is in the range from about 30° C. to about 80° C.;
maintaining the fluid bath at the hold temperature for a predetermined time period, wherein the heat from the fluid bath is transferred to the wet infiltrated preform at least partially by conduction, such that the wet infiltrated preform is transformed into the green body;
removing the pliable container from the fluid bath; and
removing the green body from the pliable container.

19. The method according to claim 18 , wherein the ceramic slurry consists of the solid particulate fillers, one or more reactive additive, the solvent, and one or more dispersants or binders;
wherein the solid particulate fillers comprise silicon carbide (SiC), silicon nitride (Si 3 N 4 ), or a mixture thereof present in a solid loading in the range of about 10 vol. % to about 70 vol. % relative to the overall volume of the ceramic slurry;
wherein the one or more reactive additives includes at least one of graphite, diamond, carbon black, molybdenum (Mo), and tungsten (W).

20. The method according to claim 18 , wherein the fluid bath is a heated bath circulator, such that heat transfer from the fluid bath to the ceramic slurry in the wet infiltrated preform is uniformly distributed.

Assignees

• Rolls Royce High Temperature Composites Inc

Inventors

• Bortoluzzi Camila S
• Shim Sungbo

Classifications

• C04B35/62871

  Silicon nitride · CPC title

• C04B35/62863

  Silicon carbide · CPC title

• C04B2235/6567

  Treatment time · CPC title

• C04B2235/616

  Liquid infiltration of green bodies or pre-forms · CPC title

• C04B2235/614

  Gas infiltration of green bodies or pre-forms · CPC title