Gelcasting polymeric precursors for producing net-shaped graphites

Abstract

The present invention discloses a method for molding complex and intricately shaped high density monolithic carbon, carbon-carbon, graphite, and thermoplastic composites using gelcasting technology. The method comprising a polymeric carbon precursor, a solvent, a dispersant, an anti-foaming agent, a monomer system, and an initiator system. The components are combined to form a suspension which is poured into a mold and heat-treated to form a thermoplastic part. The thermoplastic part can then be further densified and heat-treated to produce a high density carbon or graphite composite. The present invention also discloses the products derived from this method.

What is claimed is:  
     
         1 . A method of making a carbonaceous preform, comprising the steps of: 
 a) forming a gelcasting suspension comprising at least one polymeric carbon precursor, a monomer solution, and an initiator system;    b) polymerizing the monomer(s) in the monomer solution to form a polymer-solvent gel matrix, wherein the gelcasting suspension is formed into a solid product;    c) drying the solid product to remove the solvent;    d) heating the solid product to pyrolize the polymer formed in step (b); and    e) further heating the solid product to convert the polymeric carbon precursor to carbon.    
     
     
         2 . The method of    claim 1   , comprising the additional step of further heating the solid product to convert the carbon to graphite.  
     
     
         3 . The method of    claim 1   , comprising the additional step of infiltrating the solid product with a densifying material.  
     
     
         4 . The method of    claim 3   , wherein the densifying material is selected from the group consisting of a polymer compound, ceramic, metal, carbon or graphite.  
     
     
         5 . The method of    claim 3   , wherein the densifying material is a carbon.  
     
     
         6 . The method of    claim 5    comprising the additional step of further heating the infiltrated solid carbon product to convert the carbon densifying material to graphite.  
     
     
         7 . The method of    claim 2   , comprising the additional step of infiltrating the solid product with a densifying material.  
     
     
         8 . The method of    claim 7   , wherein the densifying material is selected from the group consisting of a polymer compound, ceramic, metal, carbon or graphite.  
     
     
         9 . The method of    claim 7   , wherein the densifying material is a carbon.  
     
     
         10 . The method of    claim 9    comprising the additional step of further heating the infiltrated solid product to convert the additional carbon densifying material to graphite.  
     
     
         11 . The method of    claim 1    wherein the polymeric carbon precursor is selected from the group consisting of mesophase pitch, isotropic pitch, solvated pitch, a blend of the aforementioned pitches, phenolics, furans, polyvinyl alcohols, polyacrylonitriles, polyimids, polyaramides, polyetheretherkeytones, polyarylacetylenes, melamines, cyanate-esters, polycyanates, or polyvinylacrylates.  
     
     
         12 . The method of    claim 1    further comprising the step of machining the solid product prior to the step of further heating the solid product to convert the polymeric precursor to carbon.  
     
     
         13 . A method of making a carbonaceous preform, comprising the steps of: 
 a) making a gelcasting mixture comprising at least one polymeric carbon precursor; at least one additive; a monomer solution and an initiator system;    b) polymerizing the monomer(s) in the monomer solution to form a polymer-solvent gel matrix, wherein the gelcasting suspension is formed into a solid product;    c) drying the solid product to remove the solvent;    d) heating the solid product to pyrolize the polymer formed in step (b); and    e) further heating the solid product to convert the polymeric carbon precursor to carbon.    
     
     
         14 . The method of    claim 13   , comprising the additional step of further heating the solid product to convert the carbon to graphite.  
     
     
         15 . The method of    claim 13   , comprising the additional step of infiltrating the solid product with a densifying material.  
     
     
         16 . The method of    claim 15    wherein the densifying material is selected from the group consisting of a polymer compound, ceramic, metal, carbon or graphite.  
     
     
         17 . The method of    claim 15   , wherein the densifying material is a carbon.  
     
     
         18 . The method of    claim 17    comprising the additional step of further heating the infiltrated solid product to convert the carbon densifying material to graphite.  
     
     
         19 . The method of    claim 14   , comprising the additional step of infiltrating the solid product with a densifying material.  
     
     
         20 . The method of    claim 19   , wherein the densifying material is selected from the group consisting of a polymer compound, ceramic, metal, carbon or graphite.  
     
     
         21 . The method of    claim 19   , wherein the densifying material is a carbon.  
     
     
         22 . The method of    claim 21    comprising the additional step of further heating the infiltrated solid product to convert the additional carbon densifying material to graphite.  
     
     
         23 . The method of    claim 11    wherein the polymeric carbon precursor is selected from the group consisting of mesophase pitch, isotropic pitch, solvated pitch, a blend of the aforementioned pitches, phenolics, furans, polyvinyl alcohols, polyacrylonitriles, polyimids, polyaramides, polyetheretherkeyture, polyarylacetylene, melamines, cyanate-esters, polycyanate, or polyvinylacrylates.  
     
     
         24 . The method of    claim 13    further comprising the step of machining the solid product prior to the step of further heating the solid product to convert the polymeric precursor to carbon.  
     
     
         25 . The method of    claim 13    wherein the additive is a carbon fiber.  
     
     
         26 . The method of    claim 25    wherein the carbon fiber is selected from the group consisting of mesophase pitch-based carbon fibers, isotropic pitch-based carbon fibers, solvated pitch-based carbon fibers, vapor grown carbon fibers, vapor grown carbon nanofibers, poly(acrylonitrile) based carbon fibers.  
     
     
         27 . The method of    claim 13    wherein the additive is a selected from the group consisting of carbon particles, carbon fibers, carbon nonfibers, carbon whiskers, carbon nanotubes, carbon fullerenes, carbon flakes, graphite powders, graphite flakes, graphite mesobeads, graphite whiskers, ceramic particles, ceramic fibers, ceramic nonfibers, ceramic whiskers, ceramic nanotubes, ceramic fullerenes, ceramic flakes, metal particles, metal fibers, metal nonfibers, metal flakes, pre-ceramic polymers, pre-metallic polymers and other additives which have a tendency to reinforce the properties of the composition.  
     
     
         28 . A method of making a thermoplastic part comprising the steps of: 
 a) forming a gelcasting suspension comprising of at least one polymeric carbon precursor, a monomer solution, and an initiator system;    b) polymerizing the monomer(s) in the monomer solution to form a polymer-solvent gel matrix, wherein the gelcasting suspension is formed into a solid product;    c) drying the solid product to remove the solvent; and    d) heating the solid product to pyrolize the polymer formed in step (b).    
     
     
         29 . The method of    claim 28   , comprising the additional step of further heating the solid product to convert the polymeric carbon precursor to carbon.  
     
     
         30 . The method of    claim 29   , comprising the additional step of further heating the solid product to convert the carbon to graphite.  
     
     
         31 . The method of    claim 29   , comprising the additional step of infiltrating the solid product with a densifying material.  
     
     
         32 . The method of    claim 31   , wherein the densifying material is selected from the group consisting of a polymer compound, ceramic, metal, carbon or graphite.  
     
     
         33 . The method of    claim 29   , wherein the densifying material a is carbon.  
     
     
         34 . The method of    claim 33    comprising the additional step of further heating the infiltrated solid product to convert the carbon densifying material to graphite.  
     
     
         35 . The method of    claim 30   , comprising the additional step of infiltrating the solid product with a densifying material.  
     
     
         36 . The method of    claim 35   , wherein the densifying material is selected from the group consisting of a polymer compound, ceramic, metal, carbon or graphite.  
     
     
         37 . The method of    claim 35   , wherein the densifying material is a carbon.  
     
     
         38 . The method of    claim 37    comprising the additional step of further heating the solid product to convert the additional carbon densifying material to graphite.  
     
     
         39 . The method of    claim 28    wherein the polymeric carbon precursor is selected from the group consisting of mesophase pitch, isotropic pitch, solvated pitch, a blend of the aforementioned pitches, phenolics, furans, polyvinyl alcohols, polyacrylonitriles, polyimids, polyaramides, polyetherethkeyture, polyarylacetylene, melamines, cyanateesters, polycyanate, or polyvinylacrylates.  
     
     
         40 . The method of    claim 28    wherein the polymeric carbon precursor is supplemented with an additive.  
     
     
         41 . The method of    claim 40    wherein the additive is a carbon fiber.  
     
     
         42 . The method of    claim 41    wherein the carbon fiber is selected from the group consisting of mesophase pitch-based carbon fibers, isotropic pitch-based carbon fibers, solvated pitch-based carbon fibers, vapor grown carbon fibers, vapor grown carbon nanofibers, poly(acrylonitrile) based carbon fibers.  
     
     
         43 . The method of    claim 40    wherein the additive is a selected from the group consisting of carbon particles, carbon fibers, carbon nonfibers, carbon whiskers, carbon nanotubes, carbon fullerenes, carbon flakes, graphite powders, graphite flakes, graphite mesobeads, graphite whiskers, ceramic particles, ceramic fibers, ceramic nonfibers, ceramic whiskers, ceramic nanotubes, ceramic fullerenes, ceramic flakes, metal particles, metal fibers, metal nonfibers, metal flakes, pre-ceramic polymers, pre-metallic polymers and other additives which have a tendency to reinforce the properties of the composition.  
     
     
         44 . The method of    claim 29    further comprising the step of machining the solid product prior to heating the solid product to convert the polymeric precursor to carbon.  
     
     
         45 . A carbonized product comprising a narrow distribution of pore sizes, and small, medium and large particles coalesced together at their contact points, wherein the small and medium particles lie in the interstitial spaces between the large particles.  
     
     
         46 . The carbonized product of    claim 45    manufactured according to the method of    claim 1   .  
     
     
         47 . The carbonized product of    claim 45   , wherein the small, medium and large particles are bonded to carbon fibers.  
     
     
         48 . The carbonized product of    claim 45    manufactured according to the method of    claim 12   .  
     
     
         49 . A graphitized product comprising a narrow distribution of pore sizes, and small, medium and large particles coalesced together at their contact points, wherein the small and medium particles lie in the interstitial spaces between the large particles.  
     
     
         50 . The graphitized product of    claim 49    manufactured according to the method of    claim 1   .  
     
     
         51 . The graphitized product of    claim 49   , wherein the small, medium and large particles are bonded to carbon fibers.  
     
     
         52 . The graphitized product of    claim 49    manufactured according to the method of    claim 12   .  
     
     
         53 . A carbon product manufactured according to the method of    claim 1   .  
     
     
         54 . A carbon product manufactured according to the method of    claim 13   .  
     
     
         55 . A graphite product manufactured according to the method of    claim 1   .  
     
     
         56 . A graphite product manufactured according to the method of    claim 13   .  
     
     
         57 . A thermoplastic part manufactured according to the method of    claim 28   .