Carbon fiber foam composites and methods for making the same
Exemplary embodiments provide methods and apparatus of forming fibrous carbon foams (FCFs). In one embodiment, FCFs can be formed by flowing a fuel rich gas mixture over a catalytic material and components to be encapsulated in a mold to form composite carbon fibers, each composite carbon fiber having a carbon phase grown to encapsulate the component in situ. The composite carbon fibers can be intertwined with one another to form FCFs having a geometry according to the mold.
1. A method of forming a fibrous carbon foam (FCF) comprising:
providing a mold comprising an internal cavity, the internal cavity comprising a predetermined geometry;
placing a catalytic material and a component to be encapsulated in the internal cavity of the mold in an orientation;
flowing a fuel rich gas mixture comprising a carbon source over the catalytic material and the components to be encapsulated at a reaction temperature of about 750° C. or less to form a plurality of composite carbon fibers, wherein each of the plurality of composite carbon fibers comprises a carbon phase grown to encapsulate the component according to the orientation of the catalytic material and the component placed in the mold; and
continuously forming the plurality of composite carbon fibers until the mold is full, wherein the plurality of composite carbon fibers are intertwined with one another to form the fibrous carbon foam (FCF) having a geometry corresponding to the predetermined geometry of the internal cavity of the mold.
2. The method of claim 1 , further comprising heating the mold to the reaction temperature in the inert gas prior to flowing the fuel rich gas mixture.
3. The method of claim 1 , further comprising cooling the FCF or the mold to room temperature in the inert gas.
4. The method of claim 1 , further comprising directing the fuel rich gas mixture into a bypass for disposition at an outlet, when the mold is full.
5. The method of claim 1 , wherein the plurality of composite carbon fibers are formed at about one atmospheric pressure to about 10 psi.
6. The method of claim 1 , wherein each of the catalytic material and the component is placed by at least partially spreading on a surface of the internal cavity of the mold, at edges of the internal cavity, in a center of the internal cavity, or combinations thereof.
7. The method of claim 1 , wherein the carbon source comprising hydrocarbon, and wherein the fuel rich gas mixture further comprises a secondary reactive gas comprising oxygen or hydrogen.
8. The method of claim 7 , wherein the fuel rich gas mixture comprises ethylene and oxygen having a molar ratio of 1:1.
9. The method of claim 1 , further comprising dispersing the catalytic material or the component at a temperature lower than the reaction temperature prior to forming the plurality of composite carbon fibers at the reaction temperature.
10. The method of claim 1 , wherein the catalytic material comprises Pd particles and the component to be encapsulated comprises silica fibers, steel foils, or a mixture thereof.
11. The method of claim 10 , wherein the step of placing a catalytic material and a component to be encapsulated in the mold in an orientation further comprises,
placing a first half amount of the silica fibers and about 60% to about 70% of a total amount of Pd particles in a bottom of the internal cavity of the mold,
placing the steel foils at a center of the internal cavity, and
placing a second half amount of the silica fibers and about 30% to about 40% of the total amount of Pd particles over the steel foils.