Abstract: An apparatus includes a first component comprising a carbon composite substrate. A high temperature coating is disposed on the surface of the carbon composite substrate. The high temperature coating includes a bond layer of a metal carbide on the surface of the substrate. The apparatus includes a second component, and braze material joining the surface of the first component to the second component. In some examples, a brake assembly may include a rotor having a surface configured to interface with another component of the brake assembly. The brake assembly includes an insert joined to the surface of the rotor without a mechanical fastener, and the insert defines a tough mechanical contact surface configured to protect the rotor.

Abstract: An example method includes combining an interlayer and a carbon fiber fabric, wherein the interlayer comprises a highly oriented milled carbon fiber ply comprising a plurality of out-of-plane carbon fibers. The method further includes winding the interlayer and the carbon fiber fabric around a core to form a composite fiber preform comprising a plurality of layers defining an annulus extending along a central axis. The method further includes densifying the composite fiber preform.

Abstract: An example method includes forming an interlayer on a carbon fiber fabric to form a composite fiber fabric. The interlayer comprises a binder. The method further includes winding the composite fiber fabric around a core to form a composite fiber preform comprising a plurality of layers defining an annulus extending along a central axis. The method further includes densifying the composite fiber preform.

Abstract: A carbon-carbon composite preform including a plurality of layers including carbon fibers or carbon-precursor fibers, the layers include a first exterior layer defining a first major surface, a second exterior layer defining a second major surface, and at least one interior layer disposed between the first exterior layer and the second exterior layer, the at least one interior layer having a peripheral region that forms a portion of an outer surface of the preform. The preform includes needled fibers, where at least some needled fibers extend through two or more layers. The preform has an exterior region and a core region, where the exterior region includes at least the peripheral region of at least one interior layer. The needled fibers define a first needled fiber number density (NFND) in the exterior region and a second greater NFND in at least a portion of the core region.

Abstract: The disclosure describes a method of forming a carbon-carbon composite component including depositing an initial carbon material into a porous preform using chemical vapor deposition (CND) or chemical vapor infiltration (CVI) to form a rigidized porous preform, infusing the rigidized porous preform with an isotropic resin, pyrolyzing the infused isotropic resin to form an isotropic carbon within pores of the rigidized porous preform, and encapsulating the isotropic carbon, with a graphitizable carbon to form the carbon-carbon composite component.

Abstract: A technique of forming a carbon-carbon composite that includes infiltrating a preform comprising carbon fibers or carbon-precursor fibers with a pitch and pyrolyzing the pitch using a controlled pressure and temperature ramp rate to control a growth of optical textures as the pitch is pyrolyzed to a coke matrix. Pyrolyzing the pitch may include initiating pyrolysis of at least some of the pitch at a first pressure less than about 2000 psi and a first temperature ramp rate between about 5° C./hr and about 50° C./hr to a first target temperature, and pyrolyzing at least some of the pitch at a second pressure greater than 2000 psi and a second temperature ramp rate between about 5° C./hr and about 50° C./hr to a second target temperature, where the second target temperature is greater than the first target temperature.

Abstract: A technique of forming a carbon-carbon composite that includes infiltrating a preform comprising carbon fibers or carbon-precursor fibers with a pitch and pyrolyzing the pitch using a controlled pressure and temperature ramp rate to control a growth of optical textures as the pitch is pyrolyzed to a coke matrix. Pyrolyzing the pitch may include initiating pyrolysis of at least some of the pitch at a first pressure less than about 2000 psi and a first temperature ramp rate between about 5 ° C./hr and about 50 ° C./hr to a first target temperature, and pyrolyzing at least some of the pitch at a second pressure greater than 2000 psi and a second temperature ramp rate between about 5 ° C./hr and about 50 ° C./hr to a second target temperature, where the second target temperature is greater than the first target temperature.

Abstract: A carbon-carbon composite preform including a plurality of layers including carbon fibers or carbon-precursor fibers, the layers include a first exterior layer defining a first major surface, a second exterior layer defining a second major surface, and at least one interior layer disposed between the first exterior layer and the second exterior layer, the at least one interior layer having a peripheral region that forms a portion of an outer surface of the preform. The preform includes needled fibers, where at least some needled fibers extend through two or more layers. The preform has an exterior region and a core region, where the exterior region includes at least the peripheral region of at least one interior layer. The needled fibers define a first needled fiber number density (NFND) in the exterior region and a second greater NFND in at least a portion of the core region.

Abstract: A method for making a carbon-carbon composite brake disc by infiltrating a porous carbon preform with a resin and carbonizing the resin-infiltrated preform at a high pressure of at least about 5,000 psi to form a densified carbon-carbon composite disc brake with a final density of at least about 1.9 g/cc. The porous carbon preform includes a plurality of fabric sheets having non-woven oxidized polyacrylonitrile fibers, pitch fibers, or rayon fibers and a basis weight in the range from about 1250 to about 3000 grams per square meter. The fabric sheets are needled together. The porous carbon preform is infiltrated with resin, which includes at least one of an isotropic resin or a mesophase resin.

Abstract: Method of making a carbon-carbon composite brake disc or pad by: needling a plurality of layers of fibrous fabric segments to one another to form a brake disc or pad preform; carbonizing the fibrous preform to provide a carbon fiber brake disc or pad preform having a fiber volume fraction in the range 17% to 30% in the brake disc or pad preform; densifying the resulting carbonized needled fibrous fabric preform with pitch (isotropic or anisotropic) or with pitch and CVD/CVI; carbonizing the resulting pitch-infiltrated carbon fiber disk to carbonize the pitch therein; heat-treating the resulting pitch-densified carbon brake disc or pad; and subjecting the carbon brake disc or pad to a final cycle of CVD/CVI processing in order to produce a carbon-carbon composite brake disc or pad having a density of at least 1.70 g/cc and having a uniform through-thickness density.

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.

Abstract: Carbon-carbon composites made by needling together woven or nonwoven fabric made from carbon-containing fibers followed by carbonizing the fabric preforms are described. The carbon fiber preforms can be needled either in a carbonized or in an uncarbonized state. The uncarbonized fiber preforms would go through a carbonization/heat-treat step following the needling process. Final preform thickness and fiber volume is also controlled at carbonization, for instance by varying the level of pressure applied to the preforms during carbonization. For example, the preforms may be unconstrained during carbonization (i.e., no pressure is applied to them) or the preforms may be constrained during carbonization, typically by means for applying pressure (e.g., weight placed on top of the preforms).

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.

Abstract: A method for the manufacture of carbon-carbon composite brake discs comprises (a) heat treating a carbon-carbon composite preform in the shape of a brake disc at 1600-2540° C., (b) directly following heat treating, subjecting the heat-treated preform to Chemical Vapor Deposition/Chemical Vapor Infiltration processing, (c) infiltrating the preform with an isotropic low to medium char-yield pitch derived from coal tar, employing Vacuum Pitch Infiltration processing or Resin Transfer Molding Processing, (d) stabilizing and carbonizing the pitch-infiltrated preform (e) machining the surfaces of the resulting carbonized preform, and (f) repeating steps (c) through (e) at least two additional times to raise the density of the carbon-carbon composite preform to at least approximately 1.75 g/cc.

Abstract: Method for producing carbon-carbon composite brake discs by: (a) providing annular nonwoven carbon fiber brake disc preforms; (b) carbonizing the brake disc preforms; (c) densifying the carbonized preforms by CVD/CVI (chemical vapor deposition/chemical vapor infiltration); (d) densifying the products of step (c) with isotropic or mesophase pitch by VPI (vacuum pitch infiltration) or RTM (resin transfer molding) processing; (e) carbonizing the preforms to remove non-carbon volatiles from the pitch and to open porosity in the pitch-infused preforms; (f) densifying the products of step (e) with isotropic or mesophase pitch by VPI or RTM processing; (g) carbonizing the preforms to remove non-carbon volatiles from pitch and to open porosity in the pitch-infused preforms; and (h) heat-treating the resulting pitch-densified carbon-carbon composite brake disc preforms. This manufacturing approach reduces lot-to-lot variability in friction performance of the resulting carbon-carbon composite brake discs.

Abstract: A method of manufacturing pitch-based carbon-carbon composite useful as a brake disc, includes (a) providing annular carbon fiber brake disc preform; (b) heat-treating the carbon fiber preform; (c) infiltrating the carbon fiber preform with pitch feedstock by VPI or RTM processing; (d) carbonizing the pitch-infiltrated carbon fiber preform; (e) repeating steps (c) and (d) to achieve a density in the carbon fiber preform of approximately 1.5 g/cc to below 1.7 g/cc; and (f) densifying the preform by CVI/CVD processing to a density higher than 1.7 g/cc. Employing lower cost VPI and/or RTM processing in early pitch densification cycles and using more expensive CVI/CVD processing only in the last densification cycle provides C-C composites in which the pitch-based components resist pullout, resulting in a longer wearing composite.

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.

Abstract: A pitch densification apparatus may be used to form a carbon-carbon composite material. In some examples, the apparatus is configured to pitch densify a material using one or more of a plurality of different pitch densification techniques. For example, the apparatus may densify a material with a selectable one of the resin transfer molding cycle, the vacuum-assisted resin transfer molding cycle, and/or the vacuum pressure infiltration cycle. The apparatus may respond to initial or changing properties of a material to be densified. In some additional examples, the apparatus includes a mold configured to receive a preform and a portion of solid pitch separate from the preform. The apparatus may include a heating source thermally coupled to the mold that is configured to heat the solid pitch above a melting temperature of the solid pitch. The apparatus may melt the pitch without external pitch melting equipment.

Abstract: Method for producing carbon-carbon composite brake discs by: (a) providing annular nonwoven carbon fiber brake disc preforms; (b) carbonizing the brake disc preforms; (c) densifying the carbonized preforms by CVD/CVI (chemical vapor deposition/chemical vapor infiltration); (d) densifying the products of step (c) with isotropic or mesophase pitch by VPI (vacuum pitch infiltration) or RTM (resin transfer molding) processing; (e) carbonizing the preforms to remove non-carbon volatiles from the pitch and to open porosity in the pitch-infused preforms; (f) densifying the products of step (e) with isotropic or mesophase pitch by VPI or RTM processing; (g) carbonizing the preforms to remove non-carbon volatiles from pitch and to open porosity in the pitch-infused preforms; and (h) heat-treating the resulting pitch-densified carbon-carbon composite brake disc preforms. This manufacturing approach reduces lot-to-lot variability in friction performance of the resulting carbon-carbon composite brake discs.

Abstract: Method for making carbon-carbon composite friction product, by: fabricating carbon fiber preform; heat-treating the carbon fiber preform; infiltrating the carbon fiber preform with a high carbon-yielding pitch using VPI (vacuum pressure infiltration) or resin transfer molding (RTM) processing; carbonizing the preform with an intermediate heat-treatment at 800-2000° C.; repeating the pitch infiltration and carbonization steps to achieve a final density of >1.75 g/cc; machining the surfaces of the preform; and applying an oxidation protection system. This approach overcomes problems inherent in lower density carbon-carbon composites by employing high carbon-yielding pitches to densify the carbon-carbon composites to a high density. The high carbon yielding pitches may include isotropic pitches, 100% anisotropic (mesophase) pitches, or mixtures of the two. They may be derived from petroleum, coal tar, or synthetic feedstocks.