Apparatus for carbon fiber processing and pitch densification

Abstract

A pitch densification apparatus may be used to form a carbon-carbon composite material. The apparatus may be used to compress a carbon fiber material, and, thereafter, pitch densify the carbon fiber material. The compression and pitch densification of the carbon fiber material may be carried out within the same mold cavity of the pitch densification apparatus. In one example, an apparatus may comprise a mold defining a mold cavity that is configured to receive a material to be densified. The mold cavity is configured to be adjusted from a first volume to a second volume less than the first volume to compress the material in the mold cavity. The example apparatus may further comprise a gas source configured to apply a gas pressure in the mold cavity to force pitch into the material in the mold cavity to densify the material, and a vacuum source configured to create a vacuum pressure in the mold cavity at least prior to the application of the gas pressure.

1 . An apparatus comprising:
 a mold defining a mold cavity configured to receive a material to be densified, wherein the mold cavity is configured to be adjusted from a first volume to a second volume less than the first volume to compress the material in the mold cavity;   a gas source configured to apply a gas pressure in the mold cavity to force pitch into the material in the mold cavity to densify the material; and   a vacuum source configured to create a vacuum pressure in the mold cavity at least prior to the application of the gas pressure.   
     
     
         2 . The apparatus of  claim 1 , wherein the mold defines a top surface, a bottom surface, and the mold cavity is defined between the top surface and the bottom surface, and wherein the top surface is configured to actuate to reduce a volume of the mold cavity from the first volume to the second volume. 
     
     
         3 . The apparatus of  claim 1 , further comprising a press configured to adjust a volume of the mold cavity, wherein the press is configured to compress the material in the mold cavity to between approximately 15 volume percent material and approximately 50 volume percent material. 
     
     
         4 . The apparatus of  claim 3 , wherein the press is configured to compress the material in the mold cavity to between approximately 17 volume percent material and approximately 30 volume percent material. 
     
     
         5 . The apparatus of  claim 4 , wherein the press comprises a hydraulic piston configured to actuate a surface of the mold to compress the material in the mold cavity. 
     
     
         6 . The apparatus of  claim 1 , wherein the gas source is configured to apply the gas pressure between approximately 10 pounds per square inch (psi) and approximately 1000 psi within the mold cavity. 
     
     
         7 . The apparatus of  claim 6 , wherein the vacuum source is configured to apply the vacuum pressure between approximately 1 torr and approximately 100 torr within the mold cavity. 
     
     
         8 . The apparatus of  claim 1 , wherein the apparatus is configured to pitch densify the material to a density between approximately 1.35 grams per cubic centimeter and approximately 1.5 grams per cubic centimeter. 
     
     
         9 . The apparatus of  claim 1 , further comprising a plurality of needles configured to extend into the mold cavity to axially entangle the material in the mold cavity. 
     
     
         10 . A method comprising:
 inserting a material a mold cavity of an apparatus, wherein the apparatus is configured to densify the material within the mold cavity using a vacuum pressure infiltration cycle;   compressing the material in the mold cavity by adjusting the mold cavity from a first volume to a second volume less than the first volume; and   pitch densifying the compressed material in the mold cavity using the vacuum pressure infiltration cycle.   
     
     
         11 . The method of  claim 10 , wherein the material to be densified comprises at least one of a carbonized polyacrylonitrile fiber or a pitch fiber. 
     
     
         12 . The method of  claim 10 , wherein the material comprises a fiber material formed into a plurality of segments, and wherein inserting the material into the mold cavity comprises inserting the plurality of segments to define a plurality of layers in the mold cavity. 
     
     
         13 . The method of  claim 10 , wherein the mold includes a top surface and a bottom surface defining at least a portion of the mold cavity, and wherein inserting the material into the mold cavity comprises:
 placing the material onto the bottom surface of the mold cavity; and   placing the top surface of the mold over the material on the bottom surface of the mold cavity to define a bounded volume for pitch densifying the material.   
     
     
         14 . The method of  claim 13 , wherein compressing the material in the mold cavity comprises actuating the top surface of the mold to compress the material in the mold cavity. 
     
     
         15 . The method of  claim 14 , wherein actuating the top surface of the mold cavity comprises extending a hydraulic piston connected to the top surface of the mold. 
     
     
         16 . The method of  claim 10 , wherein compressing the material comprises compressing the material to between approximately 17 volume percent material and approximately 30 volume percent material. 
     
     
         17 . The method of  claim 10 , further comprising, subsequent to inserting the material in the mold cavity, needling the material to axially entangle the material in the mold cavity. 
     
     
         18 . The method of  claim 10 , wherein pitch densifying the compressed material in the mold cavity using the vacuum pressure infiltration cycle comprises:
 creating a vacuum pressure in the mold cavity between approximately 1 torr and approximately 100 torr;   filling the mold cavity with melted pitch; and   applying a gas pressure in the mold cavity between approximately 10 pounds per square inch (psi) and approximately 1000 pounds per square inch to force the melted pitch into the material.   
     
     
         19 . The method of  claim 10 , wherein pitch densifying the compressed material comprises pitch densifying the compressed material to a density between approximately 1.35 grams per cubic centimeter and approximately 1.5 grams per cubic centimeter. 
     
     
         20 . The method of  claim 10 , wherein compressing the material comprises compressing the material to a density between approximately 0.25 grams per cubic centimeter and approximately 1 gram per cubic centimeter.