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 plasma treatment method that includes providing treatment chamber including an intermediate heating volume and an interior treatment volume. The interior treatment volume contains an electrode assembly for generating a plasma and the intermediate heating volume heats the interior treatment volume. A work piece is traversed through the treatment chamber. A process gas is introduced to the interior treatment volume of the treatment chamber. A plasma is formed with the electrode assembly from the process gas, wherein a reactive species of the plasma is accelerated towards the fiber tow by flow vortices produced in the interior treatment volume by the electrode assembly.

A carbon fiber manufacturing method with which high quality carbon fibers can be obtained. The carbon fiber manufacturing method includes introducing carbon fiber precursor fiber bundles that have been spread in sheet form into a flameproofing furnace, flameproofing the carbon fiber precursor fiber bundles introduced into the flameproofing furnace in a temperature range of 200 C. to 300 C., introducing the flameproofed fiber bundles obtained from the flameproofing treatment into a carbonization furnace, and carbonizing the flameproofed fiber bundles introduced into the carbonization furnace in a temperature range of 300 C. to 2500 C. The flameproofing furnace includes a heat-treatment chamber and a sealing chamber adjacent thereto and discharges air from the sealing chamber to outside of the flameproofing furnace. The space velocity (SV) (1/h) of hot air blown from the heat-treatment chamber into the sealing chamber satisfies relationship: 80SV400.

A carbon material can comprise a porous scaffold of carbon fibrils and particles of carbon black attached to the carbon fibrils. The carbon material can be provided in an atmosphere of a gas comprising one or more organic compounds, for example, methane. The carbon material and the gas can be subjected to a temperature (e.g., 1700 K) that causes the organic compound(s) to undergo pyrolysis to form carbon and hydrogen. For example, the carbon material can be used as a Joule heating element to heat the material and the gas to the pyrolysis temperature. At least some of the formed carbon can be deposited on or within the carbon material. As a result, the carbon fibrils in the material can merge to form a carbonized matrix, and the carbon black particles can become embedded within the carbonized matrix.

The invention is directed to carbon fibers having high tensile strength. The invention also provides a method and apparatus for making the carbon fibers. The method comprises advancing a precursor fiber through a plurality of passes through an oxidation oven, where stretching during the initial passes is minimized or eliminated entirely, or made negative, followed by controlled stretching over a series of passes, using rollers of increasing speed.

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.

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.

A process for preparing a carbon fiber precursor is hereby disclosed, wherein the precursor is selected from a series of solid PAN (polyacrylonitrile) fibers, wherein each member of the series contains about 0.5 mole % to about 8 mole % ammonium salt of 2-acrylamido-2-methyl propane sulfonic acid.

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.

An example oven for heating fibers includes a chamber having upper and lower portions and a supply structure between first and second ends of the chamber, wherein the supply structure is in communication with a first heating system and is configured to direct first heated gas from the first heating system into the upper portion of the chamber to heat fibers in the upper portion at a first temperature, and wherein the supply structure is in communication with a second heating system and is configured to direct second heated gas from the second heating system into the lower portion of the chamber to heat fibers in the lower portion at a second temperature different than the first temperature such that the upper and lower portions of the chamber maintain the different temperatures without a physical barrier between the upper and lower portion.