Silicon to silicon carbide conversion for ceramic matrix composite fabrication

Patent metadata

Field	Value
Publication number	US-12054433-B2
Application number	US-202017018921-A
Country	US
Kind code	B2
Filing date	Sep 11, 2020
Priority date	Sep 11, 2020
Publication date	Aug 6, 2024
Grant date	Aug 6, 2024

Abstract

Disclosed are techniques and methods for producing silicon carbide and ceramic matrix composites from hydrocarbons. In one aspect, a method includes preforming a shape using silicon carbide fibers placed into a chamber, evacuating the chamber causing a silicon and polymer slurry to enter the chamber, and pressurizing the chamber causing the silicon and polymer slurry to permeate the silicon carbide fibers. The method includes heating the chamber to cause pyrolysis of the polymer and a hydrocarbon passed into the chamber into carbon and hydrogen gas. The carbon from the pyrolyzed polymer and hydrocarbon provide a coating of carbon on the silicon in the silicon and polymer slurry. The method includes heating the chamber to a higher temperature causing the silicon to melt and react with the carbon to form silicon carbide. The formed silicon carbide and the silicon carbide fibers form the ceramic matrix composite.

First claim

What is claimed is:

1. A method of producing a silicon carbide (SiC) ceramic matrix composite, comprising:
placing a silicon carbide preform in a chamber;
evacuating the chamber using a vacuum to introduce a slurry mix of silicon particles and a polymer in the chamber to contact the silicon carbide preform;
pressurizing the chamber causing the silicon particles and polymer slurry to permeate between silicon carbide fibers of the silicon carbide preform;
heating the chamber to a first temperature causing pyrolysis of the polymer into carbon and hydrogen gas to densify silicon particles between the silicon carbide fibers of the silicon carbide preform;
passing a hydrocarbon into the chamber, wherein the heated chamber causes pyrolysis of the hydrocarbon into carbon and hydrogen gas and causes the carbon from the pyrolyzed polymer and the carbon from the pyrolyzed hydrocarbon to be coated on the silicon particles between the silicon carbide fibers of the silicon carbide preform;
stopping the passing the hydrocarbon when a molar ratio of silicon to carbon in the silicon carbide preform reaches approximately 1; and
heating the chamber to a second temperature causing the silicon particles to melt and to react with the carbon to form silicon carbide to cause the formed silicon carbide and the silicon carbide fibers to form the SiC ceramic matrix composite,
wherein the second temperature is higher than the first temperature.

2. The method of claim 1 , wherein the first temperature is about 1000 C.

3. The method of claim 1 , wherein the second temperature is about 1414 C.

4. The method of claim 1 , comprising:
using silicon particles in the silicon and polymer slurry with a particle size between 20 nanometers (nm) and 25 microns.

5. The method of claim 1 , wherein the heating the chamber to the second temperature causes a reaction between the melted silicon and carbon that is expressed as:
Si (l) +C (s) →SiC (s) .

6. The method of claim 1 , further comprising:
passing, after stopping the passing the hydrocarbon, an argon gas into the chamber.

7. The method of claim 1 , wherein the hydrocarbon comprises methane (CH 4 ).

8. The method of claim 1 , wherein the hydrocarbon comprises:
diesel, gasoline, JP8, kerosene, natural gas, propane, ethane, butane, or another hydrocarbon gas.

9. The method of claim 1 , further comprising providing an inert gas to the chamber while heating the chamber to the second temperature.

10. The method of claim 1 , wherein the second temperature is about 1100C or above.

11. The method of claim 1 , further comprising:
maintaining the first temperature in the chamber to allow the pyrolysis and densification of the silicon particles between the silicon carbide fibers of the silicon carbide preform to proceed for about one hour.

12. The method of claim 1 , further comprising:
maintaining the second temperature in the chamber to allow the formation of the SiC ceramic matrix composite to proceed for about three hours.

13. The method of claim 1 , wherein the SiC ceramic matrix is (a) without excess elemental silicon or carbon or (b) with trace quantities of silicon and carbon.

14. The method of claim 1 , wherein the SiC ceramic matrix is of a high, uniform density of at least 90% or with a thickness of up to 1 centimeter.

15. A method, comprising:
passing a hydrocarbon into a chamber containing silicon particles;
heating the chamber to a first temperature causing pyrolysis of the hydrocarbon into carbon and hydrogen gas, wherein the carbon from the hydrocarbon provides a coating of carbon on the silicon particles to produce carbon coated silicon particles; and
stopping the passing the hydrocarbon when a molar ratio of silicon to carbon in the carbon coated silicon particles is approximately 1;
infiltrating the carbon coated silicon particles into silicon carbide fiber to form a silicon carbide preform; and
heating the preform to a second temperature causing the silicon within the carbon coated silicon particles to melt, wherein the melted silicon reacts with the carbon to form silicon carbide such that the formed silicon carbide and the silicon carbide fibers form a silicon carbide (SiC) ceramic matrix composite.

16. The method of claim 15 , wherein infiltrating the carbon coated silicon particles into the silicon carbide fiber comprises:
preparing a slurry comprising the carbon coated silicon particles and a polymer; and
pressurizing the chamber causing the slurry to permeate the silicon carbide fibers to produce the silicon carbide preform.

17. The method of claim 16 , further comprising:
arranging, before the pressurizing, the silicon carbide fibers into a preformed shape, wherein the shape has been placed into the chamber.

18. The method of claim 15 , wherein the first temperature is lower than the second temperature.

19. The method of claim 15 , wherein the second temperature is about 1414C or above.

20. The method of claim 15 , wherein the hydrocarbon comprises methane (CH 4 ).

21. The method of claim 15 , wherein the hydrocarbon is diesel, gasoline, JP8, kerosene, natural gas, propane, ethane, butane, or another hydrocarbon gas.

22. The method of claim 15 , further comprising:
maintaining the first temperature in the chamber to allow the pyrolysis and the production of the carbon coated silicon particles to proceed for about one hour.

23. The method of claim 15 , wherein the SiC ceramic matrix composite has a high, uniform density of at least 90% without excess elemental silicon or carbon.

Assignees

• General Atomics

Inventors

• Zhang Jiping
• Travis Austin
• Opperman Jonas
• Jacobsen George

Classifications

• C04B2235/616

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

• C04B2235/5454

  nanometer sized, i.e. below 100 nm · CPC title

• C04B2235/5436

  micrometer sized, i.e. from 1 to 100 micron · CPC title

• C04B2235/5252

  having a specific pre-form · CPC title

• C04B2235/5244

  Silicon carbide · CPC title