There is provided an oxidation heat treatment oven including a heat treatment chamber configured to heat-treat a fiber bundle that is an aligned acrylic fiber bundle in an oxidizing atmosphere to form an oxidized fiber bundle; a slit-shaped opening configured to take the fiber bundle in and out of the heat treatment chamber; guide rollers installed at both ends of the heat treatment chamber and configured to turn the fiber bundle back; a hot air supply nozzle that has a longitudinal axis along the width of the fiber bundle traveling and that blows out hot air, in a direction substantially parallel to a traveling direction of the fiber bundle, above and/or below the fiber bundle traveling in the heat treatment chamber; and a suction nozzle configured to suck the hot air blown out from the hot air supply nozzle, in which the hot air supply nozzle satisfies disclosed conditions (1) to (3).

A method of manufacturing a stabilized fiber bundle, including travelling an acrylic fiber bundle in an oxidation oven, with the acrylic fiber bundle being conveyed by guide rollers placed on both sides outside the oxidation oven, to subject the acrylic fiber bundle to a heat treatment in an oxidizing atmosphere, wherein a direction of hot air in the oxidation oven is horizontal to a travelling direction of the fiber bundle, and a contact probability P between adjacent fiber bundles, defined by expression (1), is 2 to 18%:

P=[1−p(x){−t<x<t}]×100  (1)

wherein P represents the contact probability (%) between adjacent fiber bundles, t represents an interspace (mm) between adjacent fiber bundles, p(x) represents a probability density function of a normal distribution N(0, σ.sup.2), σ represents a standard deviation of an amplitude of vibration, and x represents a random variable under the assumption that a median amplitude of vibration is zero.

A method of manufacturing a stabilized fiber bundle, including travelling an acrylic fiber bundle in an oxidation oven, with the acrylic fiber bundle being conveyed by guide rollers placed on both sides outside the oxidation oven, to subject the acrylic fiber bundle to a heat treatment in an oxidizing atmosphere, wherein a direction of hot air in the oxidation oven is horizontal to a travelling direction of the fiber bundle, and a contact probability P between adjacent fiber bundles, defined by expression (1), is 2 to 18%:

P=[1−p(x){−t<x<t}]×100  (1)

wherein P represents the contact probability (%) between adjacent fiber bundles, t represents an interspace (mm) between adjacent fiber bundles, p(x) represents a probability density function of a normal distribution N(0, σ.sup.2), σ represents a standard deviation of an amplitude of vibration, and x represents a random variable under the assumption that a median amplitude of vibration is zero.

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.

The present invention relates to a carbon fiber carbonization apparatus using a microwave. The carbon fiber carbonization apparatus using a microwave comprises: a carbonization furnace into which the microwave is irradiated from an irradiation part disposed at one side thereof; a moving tube through which a carbon fiber moves along the inside thereof and which is mounted to pass through the carbonization furnace; and a heating element coupled to an outer circumferential surface of the moving tube to absorb the microwave so as to generate heat. A portion of the moving tube is covered by the heating element at the position, but a remaining portion is exposed at a position at which the heating element is coupled to the moving tube.

The present invention relates to a carbon fiber carbonization apparatus using a microwave. The carbon fiber carbonization apparatus using a microwave comprises: a carbonization furnace into which the microwave is irradiated from an irradiation part disposed at one side thereof; a moving tube through which a carbon fiber moves along the inside thereof and which is mounted to pass through the carbonization furnace; and a heating element coupled to an outer circumferential surface of the moving tube to absorb the microwave so as to generate heat. A portion of the moving tube is covered by the heating element at the position, but a remaining portion is exposed at a position at which the heating element is coupled to the moving tube.

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 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 for a carbon nanofiber composite, which can obtain a carbon nanofiber composite with high productivity and high activity, and which does not require removal of fluidizing materials or dispersing materials, provides a carbon nanofiber composite having improved dispersibility. The method for producing the carbon nanofiber composite includes bringing at least one catalyst and at least one particulate carbon material into contact with at least one gas containing at least one gaseous carbon-containing compound while mechanically stirring the catalyst and the particulate carbon material in a reactor. The carbon nanofiber composite includes carbon nanofibers and at least one particulate carbon material, wherein the particulate carbon material has 70% by volume or more of particles with a particle diameter of 1 μm or less, and/or a median diameter D50 by volume of 1 μm or less.