Method for debundling and dispersing carbon fiber filaments uniformly throughout carbon composite compacts before densification
A method of forming a carbon fiber reinforced carbon composite articles includes the steps of: (a) selecting carbon fiber bundles that have a sizing material that is soluble in a selected dispersing fluid; (b) mixing the selected carbon bundles and other blend components in a dispersing fluid so as to debundle the carbon fibers and to produce a slurry of blend components in which the individual carbon fibers are substantially randomly oriented and uniformly distributed throughout; and (c) removing the dispersing fluid either prior to or during the process of forming of the solids of the slurry into a carbon fiber reinforced carbon composite article having individual carbon fibers substantially randomly oriented and uniformly distributed throughout.
1 . A method of making a precursor carbon fiber reinforced carbon composite article, the method comprising the steps of:
(a) providing a plurality of blend components, including
carbon fiber bundles, each bundle comprising carbon fibers bound by a sizing material; and
a matrix material;
(b) providing a dispersing fluid adapted to dissolve the sizing material;
(c) forming a slurry by combining the dispersing fluid and the blend components;
(d) removing at least a portion of the dispersing fluid so as to form a precursor mixture; and
(e) molding the precursor mixture so as to form a precursor carbon fiber reinforced carbon composite article wherein said carbon fibers are generally randomly oriented and uniformly dispersed through out the article.
2 . The method of claim 1 , wherein said sizing material comprises a water-soluble sizing material, and
wherein said dispersing fluid comprises water.
3 . The method of claim 2 , wherein said water-soluble sizing material comprises a water-soluble polyamide.
4 . The method of claim 1 , wherein said sizing material comprises a sizing material soluble in a selected polar solvent, and
wherein said dispersing fluid comprises said selected polar solvent.
5 . The method of claim 4 , wherein said selected polar solvent comprises an alcohol.
6 . The method of claim 5 , wherein said alcohol comprises ethanol.
7 . The method of claim 1 , wherein generally each said carbon fiber bundle comprises between about 2,000 and about 50,000 carbon fibers.
8 . The method of claim 7 , wherein generally each said carbon fiber bundle comprises about 2,000 and about 20,000 carbon fibers.
9 . The method of claim 1 , wherein said carbon fiber bundles comprise carbon fibers selected from the group including: pitch-based carbon fibers, mesophase pitch-based carbon fibers, isotropic pitch-based carbon fibers, polyacrylonitrile-based carbon fibers, rayon and combinations thereof.
10 . The method of claim 1 , wherein generally each said carbon fiber bundle has a length of between about 5 mm and about 40 mm.
11 . The method of claim 1 , wherein step (a) includes providing carbon fiber bundles in an amount between about 0.5% and about 50% by weight of the blend components.
12 . The method of claim 1 , wherein step (b) includes providing at least about a dispersion volume of dispensing fluid.
13 . The method of claim 12 , wherein the amount of carbon fibers provided in step (a) defines a fiber volume, and
wherein the dispersion volume provided in step (b) is equal to at least about a dispersing ratio multiplied by said fiber volume.
14 . The method of claim 13 , wherein the dispersing ratio is at least about 200%.
15 . The method of claim 1 , wherein step (c) comprises the steps of:
mixing the carbon fiber bundles and the dispersion fluid for a first period of time such that the sizing material generally dissolves and such that the debundled carbon fibers generally disperse throughout the dispersion fluid so as to form a resultant mixture; and
mixing the resultant mixture and the remainder of the blend components for a second period of time so as to form a slurry.
16 . The method of claim 1 , wherein step (c) comprises:
mixing the blend components, including the carbon fiber bundles so as to form a dry mix;
mixing the dispersion fluid and the dry mix for a first period of time so as to form a slurry having carbon fibers generally randomly oriented and uniformly dispersed throughout.
17 . A method of making a precursor carbon composite mixture, the method comprising the steps of:
(a) providing a plurality of blend components, including
carbon fiber bundles in an amount between about 0.5% and about 50% by weight of the blend components, wherein generally each said carbon fiber bundle comprises between about 2,000 and about 50,000 carbon fibers bound by a water soluble sizing material; and
a matrix material;
(b) providing at least a dispersing volume of water;
(c) forming a slurry by combining the water and the blend components; and
(d) removing at least a portion of the water so as to form a precursor carbon composite mixture wherein said carbon fibers are generally randomly oriented and uniformly dispersed throughout the mixture.
18 . The method of claim 17 , wherein step (c) comprises the steps of:
mixing the carbon fiber bundles and the dispersion fluid for a first period of time such that the sizing material generally dissolves and such that the debundled carbon fibers generally disperse throughout the dispersion fluid so as to form a resultant mixture; and
mixing the resultant mixture and the remainder of the blend components for a second period of time so as to form a slurry.
19 . The method of claim 17 , wherein step (c) comprises:
mixing the blend components, including the carbon fiber bundles so as to form a dry mix;
mixing the dispersion fluid and the dry mix for a first period of time so as to form a slurry having carbon fibers generally randomly oriented and uniformly dispersed throughout.
20 . A method of making a carbon fiber reinforced carbon composite article, the method comprising the steps of:
(a) providing a plurality of blend components, including
carbon fiber bundles in an amount between about 0.5% and about 50% by weight of the blend components, wherein generally each said carbon fiber bundle comprises between about 2,000 and about 20,000 carbon fibers bound by a water soluble sizing material; and
a matrix material;
(b) providing at least a dispersing volume of water;
(c) forming a slurry by combining the water and the blend components;
(d) removing at least a portion of the water so as to form a precursor mixture wherein said carbon fibers are generally randomly oriented and uniformly dispersed throughout the mixture;
(e) molding the precursor mixture so as to form a precursor carbon composite article; and
(f) carbonizing the precursor carbon composite article; and
(g) graphitizing the carbonized article so as to form a carbon fiber reinforced carbon composite article.
21 . The method of claim 20 , wherein the blend components comprise at least one floured or powdered blend component.
22 . The method of claim 20 , wherein the matrix material comprises floured or powdered pitch.
23 . The method of claim 20 , further including the step of densification.
24 . The method of claim 20 , wherein steps (d) , (e) and (f) are performed by means of compressive and resistive heating.