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 of forming a densified preform or composite part is disclosed that includes partially densifying a porous preform, forming channels in the partially densified preform that open to an exterior surface of the partially densified preform, infiltrating a densifying agent, such as pitch, into at least some of the channels of the partially densified preform, at least partially stabilizing the densifying agent, including heating at a first temperature, such that cracks form within the densifying agent, and exposing the preform to an oxidizing agent, and heating the at least partially stabilized preform at a second temperature to carbonize at least the stabilized densifying agent. A partially densified preform including a densifying agent disposed at least in such channels also is disclosed.

Abstract: A carbon fiber preform that includes a plurality of fibrous layers stacked together and a plurality of sacrificial fibers that bind the plurality of fibrous layers together, where at least one fibrous layer of the plurality of fibrous layers includes a plurality of carbon fibers or carbon fiber precursor fibers.

Abstract: In some examples, a method including depositing a resin and a plurality of carbon fibers via a print head of a three-dimensional printing system to form a carbon fiber preform including a plurality of individual carbon fiber layers, wherein each individual layer of the plurality of individual carbon fiber layers includes the resin and carbon fibers, and wherein the carbon fiber preform exhibits at least one of a non-uniform composition of the resin within the preform, different types of the carbon fibers within the preform, or non-uniform fiber orientation within the preform.

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 brake disc rotor or stator is manufactured with slots in the interior face of the disc. A paste comprised of a fine powder of a carbide-forming metal along with fine carbon powder, suspended in an organic binder, is applied to the force-bearing areas in the rotor slot faces or the stator slot faces. The disc is then placed into a furnace in a nitrogen atmosphere and heated to the ignition temperature. When the furnace reaches the ignition temperature, a combustion reaction begins that creates a molten liquid ceramic material on the slot face. Upon cooling, the resulting brake disc has a tough, hard, abrasion-resistant ceramic surface on the portion of the brake disc slot that bears pressure.

Abstract: In some examples, a method includes depositing a mixture including a resin and an additive powder via a print head of a three-dimensional printing system to form a carbon fiber preform including a plurality of individual carbon fiber layers, wherein each individual layer of the plurality of individual carbon fiber layers includes a plurality of carbon fibers and the mixture of the resin and the additive powder.

Abstract: In some examples, the disclosure describes a method including depositing a first layer including a resin and at least one of a carbon fiber or a carbon fiber precursor material on a work surface of a three-dimensional printing system, carbonizing at least the resin of the first layer using a carbonizer attached to the three-dimensional printer to form a first layer of carbon-carbon composite including carbon fibers and carbonized matrix material, depositing an additional layer including a resin and at least one of a carbon fiber or a carbon fiber precursor material of material on the first layer of carbon-carbon composite, and carbonizing at least the resin of the additional layer using the carbonizer to form an additional layer of carbon-carbon composite on the first layer of carbon-carbon composite.

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 heating a mixture of fibers that includes sacrificial fibers and carbon fiber precursor fibers to a temperature between about 170° C. and about 400° C., such that the sacrificial fibers are substantially removed and a plurality of channels remain in a preform precursor, and carbonizing the carbon fiber precursor fibers to form a porous carbon fiber preform. Also disclosed is a technique of heating a mixture of fibers that includes sacrificial fibers and carbon fibers to a temperature between about 170° C. and about 400° C., such that the sacrificial fibers are substantially removed and a plurality of channels remain, and infiltrating a densifying agent into at least the plurality of channels. Also disclosed is an article including a mixture of fibers that includes sacrificial fibers and carbon fiber precursor fibers or carbon fibers.

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: 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 some examples, a method including depositing a resin and a plurality of carbon fibers via a print head of a three-dimensional printing system to form a carbon fiber preform including a plurality of individual carbon fiber layers, wherein each individual layer of the plurality of individual carbon fiber layers includes the resin and carbon fibers, and wherein the carbon fiber preform exhibits at least one of a non-uniform composition of the resin within the preform, different types of the carbon fibers within the preform, or non-uniform fiber orientation within the preform.

Abstract: In some examples, the disclosure describes a method including depositing a first layer including a resin and at least one of a carbon fiber or a carbon fiber precursor material on a work surface of a three-dimensional printing system, carbonizing at least the resin of the first layer using a carbonizer attached to the three-dimensional printer to form a first layer of carbon-carbon composite including carbon fibers and carbonized matrix material, depositing an additional layer including a resin and at least one of a carbon fiber or a carbon fiber precursor material of material on the first layer of carbon-carbon composite, and carbonizing at least the resin of the additional layer using the carbonizer to form an additional layer of carbon-carbon composite on the first layer of carbon-carbon composite.

Abstract: A carbon fiber preform that includes a plurality of fibrous layers stacked together and a plurality of sacrificial fibers that bind the plurality of fibrous layers together, where at least one fibrous layer of the plurality of fibrous layers includes a plurality of carbon fibers or carbon fiber precursor fibers.

Abstract: A technique of forming a carbon-carbon composite material includes infusing a liquid carbonizable precursor into a porous preform, and the infused precursor is subsequently pyrolyzed to convert the precursor to isotropic carbon. The preform then can be densified with a densifying agent, followed by infusion of the liquid carbonizable precursor into the densified preform. In some examples, after pyrolyzing the liquid carbonizable precursor, isotropic carbon extends substantially throughout a volume of the carbon-carbon composite material.

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: In some examples, a method includes depositing a mixture including a resin and an additive powder via a print head of a three-dimensional printing system to form a carbon fiber preform including a plurality of individual carbon fiber layers, wherein each individual layer of the plurality of individual carbon fiber layers includes a plurality of carbon fibers and the mixture of the resin and the additive powder.

Abstract: In some examples, a method for forming a carbon fiber preform comprises depositing a composite material on a substrate to form a first layer of the composite material, wherein the composite material comprises a carbon reinforcement material mixed in a resin matrix material; and depositing the composite material on the first layer to form a second layer on the first layer, wherein the carbon fiber preform includes the first layer of the composite material and the second layer of composite material, and includes the carbon reinforcement material and the resin matrix material.