Abstract: A liquid carbonizable precursor is infused into a porous preform, and the infused precursor is subsequently pyrolyzed to convert the precursor to a carbon. The carbon enhances rigidity of the preform. In some examples, the preform can be densified to define a carbon-carbon composite brake disc for use in the aerospace industry.

Abstract: In one example, a method comprises densifiying a carbonized preform via at least one of resin transfer molding (RTM), vacuum pitch infiltration (VPI) and chemical vapor infiltration/chemical vapor deposition (CVI/CVD), heat treating the densified preform to open internal pores of the densified preform, and infiltrating the internal pores of the densified preform with low viscosity resin to increase the density of the preform.

Abstract: In the manufacture of carbon-carbon composite brake discs, migration of anti-oxidant substances into the friction surfaces is prevented by limiting or eliminating surface porosity in the carbon-carbon composite brake materials. The method includes infusing a suitable resin into pores in surface layers of the carbon-carbon composite disc and then charring the resin-infused disc to convert the resin in the pores to pyrolytic carbon. The resin may be infused into the carbon disc by submerging the disc in a molten resin. Prior to submerging the disc in the molten resin, the disc may subjected to a vacuum to remove air from the pores. While the disc is submerged in the molten resin, the pressure in the pressurizable vessel may increased to force the molten resin into the open porosity of the disc.

Abstract: In one example, a method includes mixing a plurality of carbon fibers in a liquid carrier to form a mixture, depositing the carbon fiber mixture in a layer, forming a plurality of corrugations in the carbon fiber layer, and rigidifying the corrugated carbon fiber layer to form a corrugated carbon fiber preform. In another example, a method includes substantially aligning a first ridge on a first surface of a first corrugated carbon fiber preform and a first groove on a first surface of a second corrugated carbon fiber preform, bringing the first surface of the first corrugated carbon fiber preform into contact with the first surface of the second corrugated carbon fiber preform, and densifying the first corrugated carbon fiber preform and the second carbon fiber preform to bond the first corrugated carbon fiber preform and the second carbon fiber preform.

Abstract: In one example, a method includes defibrillating at least one carbon fiber to form a plurality of carbon fiber filaments, melting pitch to form molten pitch, and mixing the plurality of carbon fiber filaments and the molten pitch to form a substantially homogeneous mixture of carbon fiber filaments. In another example, a method includes mixing a plurality of carbon fiber filaments having a length between about 6.35 millimeters and about 50.8 millimeters in molten pitch to form a substantially homogeneous mixture of carbon fiber filaments within the molten pitch, wherein mixing the plurality of carbon fiber filaments does not substantially change an average length of the plurality of carbon fiber filaments.

Abstract: In one example, a method includes mixing a plurality of carbon fibers in a liquid carrier to form a mixture, depositing the carbon fiber mixture in a layer, forming a plurality of corrugations in the carbon fiber layer, and rigidifying the corrugated carbon fiber layer to form a corrugated carbon fiber preform. In another example, a method includes substantially aligning a first ridge on a first surface of a first corrugated carbon fiber preform and a first groove on a first surface of a second corrugated carbon fiber preform, bringing the first surface of the first corrugated carbon fiber preform into contact with the first surface of the second corrugated carbon fiber preform, and densifying the first corrugated carbon fiber preform and the second carbon fiber preform to bond the first corrugated carbon fiber preform and the second carbon fiber preform.

Abstract: In one example, a method includes defibrillating at least one carbon fiber to form a plurality of carbon fiber filaments, melting pitch to form molten pitch, and mixing the plurality of carbon fiber filaments and the molten pitch to form a substantially homogeneous mixture of carbon fiber filaments. In another example, a method includes mixing a plurality of carbon fiber filaments having a length between about 6.35 millimeters and about 50.8 millimeters in molten pitch to form a substantially homogeneous mixture of carbon fiber filaments within the molten pitch, wherein mixing the plurality of carbon fiber filaments does not substantially change an average length of the plurality of carbon fiber filaments.

Abstract: A metal powder is applied to the surface of the area of a carbon-carbon composite brake disc to be protected against migration of antioxidant. The metal powder may be titanium powder or tungsten powder. A chemical reaction between the metal powder and carbon is then initiated by heating the powder-coated brake to the ignition temperature via application of electric current (Joule preheating) or by heating it in a furnace. Upon combustion, the metal particles react with carbon in the composite, forming liquid carbide that flows into pores of the composite brake disc to be protected.

Abstract: A liquid carbonizable precursor is infused into a porous preform, and the infused precursor is subsequently pyrolyzed to convert the precursor to a carbon. The carbon enhances rigidity of the preform. In some examples, the preform can be densified to define a carbon-carbon composite brake disc for use in the aerospace industry.

Abstract: Method of protecting carbon-carbon composite brake disc against migration of anti-oxidant composition through the porosity of the composite brake disc. The method starts with a porous carbon-carbon composite brake disc, and densifies it to a density of 1.70 grams per cubic centimeter or higher. The densified brake disc is then machine to the required dimensions. The pores in the densified brake disc are closed by subjecting it to CVD/CVI processing employing (i) a gaseous feedstock comprising natural gas spiked with 10 to 25% of a more reactive gas, and/or (ii) a temperature in the range of 1100° C. to 1500° C., and/or (iii) a gas pressure in the range 10 to 100 torr, and/or (iv) a gas flow rate of 300 cc/min to 450 cc/min. CVD/CVI processing carried out using these parameters deposits carbon within and closes the pores of the surface area of the carbon-carbon composite brake disc.

Abstract: A metal powder is applied to the surface of the area of a carbon-carbon composite brake disc to be protected against migration of antioxidant. The metal powder may be titanium powder or tungsten powder. A chemical reaction between the metal powder and carbon is then initiated by heating the powder-coated brake to the ignition temperature via application of electric current (Joule preheating) or by heating it in a furnace. Upon combustion, the metal particles react with carbon in the composite, forming liquid carbide that flows into pores of the composite brake disc to be protected.

Abstract: In the manufacture of carbon-carbon composite brake discs, migration of anti-oxidant substances into the friction surfaces is prevented by limiting or eliminating surface porosity in the carbon-carbon composite brake materials. The method includes infusing a suitable resin into pores in surface layers of the carbon-carbon composite disc and then charring the resin-infused disc to convert the resin in the pores to pyrolytic carbon. The resin may be infused into the carbon disc by submerging the disc in a molten resin. Prior to submerging the disc in the molten resin, the disc may subjected to a vacuum to remove air from the pores. While the disc is submerged in the molten resin, the pressure in the pressurizable vessel may increased to force the molten resin into the open porosity of the disc.

Abstract: An apparatus for bonding a first carbon composite to a second carbon composite through a reactant layer includes a housing, and a pair of conductive press plates electrically isolated from the housing. The press plates are adapted to position the two parts to be bonded with a reactant layer therebetween. The press plates are subjected to an electrical potential and a clamping force, sufficient to initiate a combustion reaction that creates a molten ceramic to bond together the carbon-carbon composites.

Abstract: Constraint fixture for processing annular preforms. The constraint fixture is made up of a lower plate, a top plate, a ring for the outside diameter of an annular preform being treated within the constraint fixture, and a ring for the inside diameter of the annular preform. The outside diameter and inside diameter rings are made of thin flexible sheet metal strips or thin flexible carbon-carbon composite strip material. The thin flexible strips are joined together by deformable joints, so that the flexible constraint system retains pitch within the fibrous matrix of the preform. The outside diameter strips may be joined together by expandable joints and the inside diameter strips may be joined together by collapsible joints. Also, a method of avoiding damage to an annular fibrous preform, e.g., an aircraft brake disc preform, during a carbonization procedure. This method involves carbonizing the annular fibrous preform in the constraint fixture of the invention.

Abstract: Method of carbonizing pitch-infiltrated fibrous annular preform by: infiltrating the preform with pitch; placing the pitch-infiltrated preform in a constraint fixture having an ejector base plate, an inner wall, an outer wall, and a top press plate; selecting the relative sizes of the preform and the constraint fixture so that a layer of inert friable material may be situated between the preform and walls of the constraint fixture; placing inert friable material (e.g., activated carbon) between the preform and the top, bottom, and walls of the constraint fixture; and subjecting the pitch-infiltrated fibrous preform to carbonization in the constraint fixture. The activated carbon or other inert friable material adsorbs pitch molecules that escape the preform during carbonization, which reduces problems with foaming.

Abstract: Method of manufacturing dense carbon-carbon composite material by: infiltrating a fibrous preform with pitch to form pitch-infiltrated preform; carbonizing the pitch-infiltrated preform; injecting resin or pitch into the preform in a mold; oxygen stabilizing the filled preform and carbonizing and heat-treating the oxygen-stabilized impregnated preform; and subjecting the preform to a single final cycle of chemical vapor deposition. This process reduces densification time as compared to comparable conventional carbon-carbon composite manufacturing procedures.

Abstract: Process for producing carbon-carbon composite preform, by: providing short carbon fiber segments or short carbon fiber precursor segments; providing pitch in particulate form; combining blend comprising the fiber segments and pitch particles in a mold; subjecting the resulting mixture of fibers and pitch in the mold to an elevated pressure ranging at a temperature above the melting/softening point of the pitch to create an uncarbonized preform; cooling the preform to below its softening point and removing it from the mold; placing the preform in a constraint fixture; and carbonizing the combined components in the constraint fixture at an elevated temperature for a period of time of sufficient to provide a preform having a density in the range 0.8-1.6 grams per cubic centimeter.

Abstract: A resin transfer molding (RTM) apparatus (10) that includes: an extruder (4); at least two mold cavities (15) contained within a mold (16, 18) in the apparatus, arranged so that resin can be extruded from the extruder (4) into the mold; a nozzle (20) for delivering resin from the extruder (4) into the mold; runners (25) in the body of the mold to deliver resin from the nozzle (20) to a mold cavity (15) within the mold; a venting area (29) contiguous to each mold cavity to permit gases to escape from the mold cavity (15) when the mold cavity is infiltrated with resin; and a press (12) to force the mold (16, 18) closed during at least resin injection. An advantageous feature of the present invention is that the mold may be configured to accept a part (19) that is characterized by variations in length, width, and/or thickness, such as a wheel beam key. Also, an RTM process. The process includes: placing a porous preform, e.g.

Abstract: Method of making a carbon-carbon composite article such as an aircraft brake disc. The method includes: selecting carbon fiber precursors, having limited shrinkage in the axial direction when carbonized, in the form of individualized chopped or cut fibers; placing the selected chopped or cut carbon fiber precursors into a preform mold configured in the form of a brake disc to form a fibrous matrix; and then needling the molded fibrous matrix to provide it with three-dimensional structural integrity and to reduce layering. The carbon fiber precursor matrix may subsequently be infused with liquid carbon matrix precursor, the impregnated matrix may be carbonized; e.g., at 600-1800° C. for 1-10 hours to provide a preform having a density of at least about 1.1 g/cc, and the carbonized preform may be further densified to a density of at least about 1.6 g/cc by known liquid resin infiltration techniques and/or by conventional CVI/CVD processing.

Abstract: Method for manufacturing a carbonized carbon-carbon composite preform, by: mixing (a) chopped carbon fiber, chopped stabilized pitch fiber, or chopped oxidized polyacrylonitrile (PAN) fiber, (b) thermoplastic pitch binder powder, and (c) activated carbon powder to form a mixture of 15-60 parts by weight of chopped carbon fiber or chopped stabilized pitch fiber or chopped oxidized PAN, 28-83 parts by weight of thermoplastic pitch binder powder, and 1-12 parts by weight of activated carbon powder; depositing this mixture into a mold; pressing/heating the materials in the mold to form a preform by compaction; removing the compacted preform from the mold; and carbonizing the compacted preform. The preform is preferably configured in the form of an aircraft landing system brake disc.