A method for joule carbonization of fibers includes subjecting the fibers, made from an intrinsically electrically-conductive material, to a current density sufficient to heat the fibers to a carbonization temperature of between 900-2000° C. whereby the fibers are carbonized into carbon fibers. A method for joule graphitization of fibers includes subjecting the fibers, made from an intrinsically electrically-conductive material, to a current density sufficient to heat the fibers to a graphitization temperature of between 2400-3000° C. whereby the fibers are graphitized into graphitic carbon fiber.

A method of producing an oxidized fiber bundle includes heat-treating an acrylic fiber bundle aligned in a heat treatment chamber in which hot air is circulated while causing the acrylic fiber bundle to run on direction-changing rollers disposed on both ends of an outside of the heat treatment chamber, wherein first hot air is supplied in a direction substantially parallel to a running direction of the acrylic fiber bundle, and second hot air is supplied from above the acrylic fiber bundle at an angle of 20 to 160° with respect to a wind direction of the first hot air, so that the second hot air passes at least a part of a running acrylic fiber bundle in a longitudinal direction.

A method for making carbon fiber in which the tensile strength of carbon fiber is increased without dehumidifying the ambient air that enters every oxidation oven in a multiple oxidation oven system. A positive effect on tensile strength is provided when ambient air entering only the first oven in a series of oxidation ovens is dehumidified. In addition, the ambient air entering the last oven is not dehumidified when one or more of the preceding oxidation ovens is operated with dehumidified air.

A method of manufacturing a stabilized fiber bundle is described, which includes subjecting an acrylic fiber bundle aligned, to a heat treatment in an oxidizing atmosphere, with the acrylic fiber bundle being turned around by a guide roller placed on each of both ends outside a hot air heating-type oxidation oven, wherein an air velocity Vm of first hot air sent through a supply nozzle(s) disposed above and/or under a fiber bundle travelled in the oxidation oven, in a substantially horizontal direction to a travelling direction of the fiber bundle, and an air velocity Vf of second hot air flowing in a fiber bundle passing a flow channel in which the fiber bundle is travelled that satisfies expression 1)

0.2≤Vf/Vm≤2.0   1)

to produce a high-quality stabilized fiber bundle and a high-quality carbon fiber bundle at high efficiencies without any process troubles.

A method manufactures a flame-retardant fiber bundle by flame retarding treatment of a polyacrylonitrile-based precursor fiber at 200-300° C. in an oxidizing atmosphere, wherein a fiber bundle is caused to travel so as to sequentially pass between an nth roller and an (n+1)th roller (n being an integer of at least 1 and no more than [m−1]) in a roller group formed from m (m being an integer of 3 or greater) contiguously set rollers, the roller axes of the m continuously set rollers being parallel to each other and perpendicular to the direction of travel of the fiber bundle, the roller diameter being 5-30 mm, and the specific gravity of the fiber bundle being 1.20-1.50.

A method of producing carbon fibers includes the step of providing polyacrylonitrile precursor polymer fiber filaments. The polyacrylonitrile precursor filaments include from 87-97 mole % acrylonitrile, and less than 0.5 mole % of accelerant functional groups. The filaments are no more than 3 deniers per filament. The polyacrylonitrile precursor fiber filaments can be arranged into tows of at least 150,000 deniers per inch width. The arranged polyacrylonitrile precursor fiber tows are stabilized by heating the tows in at least one oxidation zone containing oxygen gas and maintained at a first temperature T.sub.1 while stretching the tows at least 10% to yield a stabilized precursor fiber tow. The stabilized precursor fiber tows are carbonized by passing the stabilized precursor fiber tows through a carbonization zone. Carbon fibers produced by the process are also disclosed.

A method for producing a carbon material, the method including a step of performing a carbonization treatment by heating an organic polymer material to a temperature higher than 400° C. in a non-oxidizing atmosphere containing a gaseous substance (A) composed of at least one of acetylene and an acetylene derivative.

Systems and methods are provided for fabricating carbon nanostructures by low voltage near-field electromechanical spinning (LV-NFEMS). Processes described herein can produce ˜2-5 nm carbon nanowires with ultrahigh electrical conductivity using top-down and controlled reductive techniques from a polymer. Configurations are also provided to allow for deposition control and fiber elongation/alignment. One embodiment uses a low voltage near-field electromechanical spinning process to produce a polymer fiber from a polymer solution. Another embodiment of the method uses pyrolysis to convert the produced polymer fiber into a ˜2-5 nm carbon nanowire. System configurations provide advancements in polymer droplet control and control of a sustained jet of polymer solution with the use low voltages. Systems and processes described herein can include use of an array of polymer precursor nanofibers suspended onto a silicon substrate and converted to carbon nanowires. In another embodiment, ultra-thin carbon fibers can be integrated onto a carbon electrode scaffold.

A carbon fiber manufacturing method includes joining first and second target fiber bundles with a joining fiber bundle, and carbonizing the joined bundles by feeding them through one or more carbonization furnaces. The joining includes forming an overlap between a first end of the joining fiber bundle and a second end of the first target fiber bundle and jetting a fluid to the overlap to form a first entangled portion, and forming an overlap between a second end of the joining fiber bundle and a first end of the second target fiber bundle and jetting a fluid to the overlap to form a second entangled portion. When the first and second entangled portions each have two or more entangling points with a tensile strength not less than 400 N, the relationship defined by the inequality is satisfied: 40>{L2/(L2−A)}×(S+13), where L2 is a length (mm) of an elongation section inside a first carbonization furnace upstream in a feeding direction of the fiber bundles, A is a maximum distance (mm) between an entangling point in the first entangled portion and an entangling point in the second entangled portion, and S is an elongation (%) of the joined fiber bundles fed through the carbonization furnace.

A furnace for the thermal treatment, particularly for carbonization and/or graphitization, of material, particularly of fibers, particularly of fibers made from oxidized polyacrylonitrile (PAN), the furnace having a furnace housing and a process chamber located in the interior chamber of the furnace housing, which is delimited by a process chamber housing and into which the material to be treated can be introduced. A process chamber atmosphere prevailing in the process chamber can be heated by means of a heating system. An insulation layer thermally insulates the process chamber. The insulation layer is an insulation fill made from a solid particulate material.