Provided is a carbon fiber with a strand modulus of elasticity from 240 to 300 GPa, an elongation of 2.65% or more, and a strain energy density of 95 J/mm.sup.3 or more, which can improve the impact resistance of carbon fiber composite materials.

The present disclosure relates generally to carbon fibers having high tensile strength and modulus of elasticity, as well as a process for the manufacture of such carbon fiber. The process comprises spinning a polymer/solvent solution into a solvent/water bath in the range of 78%-85% solvent, thereby producing a dense fiber structure, and subsequently carbonizing the polymer precursor fiber at a lower than typical carbonization temperature to form carbon fibers.

The present disclosure relates generally to carbon fibers having high tensile strength and modulus of elasticity, as well as a process for the manufacture of such carbon fiber. The process comprises spinning a polymer/solvent solution into a solvent/water bath in the range of 78%-85% solvent, thereby producing a dense fiber structure, and subsequently carbonizing the polymer precursor fiber at a lower than typical carbonization temperature to form carbon fibers.

The present invention relates to a method for producing a carbon fiber. In the method for producing the carbon fiber, a high pure acrylonitrile monomer with specific contents of impurities and a comonomer are used to produce an acrylonitrile copolymer, and the acrylonitrile copolymer is subjected to a spinning operation, a stretching operation, an oxidation treatment and a carbonization treatment in sequence, for obtaining the carbon fiber. The acrylonitrile copolymer with an appropriate falling-ball viscosity and an appropriate weight-average molecular weight is beneficial to the spinning operation, thereby reducing an inner pore diameter and enhancing strength of the resulted carbon fiber.

The present invention relates to a method for producing a carbon fiber. In the method for producing the carbon fiber, a high pure acrylonitrile monomer with specific contents of impurities and a comonomer are used to produce an acrylonitrile copolymer, and the acrylonitrile copolymer is subjected to a spinning operation, a stretching operation, an oxidation treatment and a carbonization treatment in sequence, for obtaining the carbon fiber. The acrylonitrile copolymer with an appropriate falling-ball viscosity and an appropriate weight-average molecular weight is beneficial to the spinning operation, thereby reducing an inner pore diameter and enhancing strength of the resulted carbon fiber.

A furnace for thermal treatment, in particular for carbonization and/or graphitization, of material, in particular fibers, in particular fibers of oxidized polyacrylonitrile PAN. During the thermal treatment, a pyrolysis gas is released from the material. The furnace includes a housing, a process space, which is located in the interior of the housing and is delimited by a process space housing and through which the material can be fed, a heating system for heating a process space atmosphere prevailing in the process space, and an extraction system for suctioning process space atmosphere laden with pyrolysis gas from the process space. The extraction system has at least one suction device having a suction channel, which is delimited by a channel wall and which is connected to the process space by means of a suction opening. The suction opening is arranged in a region of the process space in which, during operation of the furnace a temperature prevails at which no or only moderate chemical reactions occur between the pyrolysis gas and the process space housing and/or the channel wall.

A furnace for thermal treatment, in particular for carbonization and/or graphitization, of material, in particular fibers, in particular fibers of oxidized polyacrylonitrile PAN. During the thermal treatment, a pyrolysis gas is released from the material. The furnace includes a housing, a process space, which is located in the interior of the housing and is delimited by a process space housing and through which the material can be fed, a heating system for heating a process space atmosphere prevailing in the process space, and an extraction system for suctioning process space atmosphere laden with pyrolysis gas from the process space. The extraction system has at least one suction device having a suction channel, which is delimited by a channel wall and which is connected to the process space by means of a suction opening. The suction opening is arranged in a region of the process space in which, during operation of the furnace a temperature prevails at which no or only moderate chemical reactions occur between the pyrolysis gas and the process space housing and/or the channel wall.

SiC matrix composite material, where heat-resistant long fiber such as carbon fiber is employed as a material for reinforcement and SiC is employed for the matrix, which significantly improves mechanical properties such as strength and toughness. The SiC matrix composite material, includes a SiC matrix and heat-resistant long fiber, wherein the SiC matrix includes both of alpha-type SiC and beta-type SiC, and the alpha-type SiC and the beta-type SiC are detected by micro-region X-ray diffraction with an X-ray beam diameter of no greater than 300 micrometers substantially at every region of every cross-section of the SiC matrix, the beta-type SiC has an average crystallite size that is no greater than 500 nm and greater than an average crystallite size of the alpha-type SiC, and the SiC matrix composite material has a porosity of no greater than 20% by volume.

SiC matrix composite material, where heat-resistant long fiber such as carbon fiber is employed as a material for reinforcement and SiC is employed for the matrix, which significantly improves mechanical properties such as strength and toughness. The SiC matrix composite material, includes a SiC matrix and heat-resistant long fiber, wherein the SiC matrix includes both of alpha-type SiC and beta-type SiC, and the alpha-type SiC and the beta-type SiC are detected by micro-region X-ray diffraction with an X-ray beam diameter of no greater than 300 micrometers substantially at every region of every cross-section of the SiC matrix, the beta-type SiC has an average crystallite size that is no greater than 500 nm and greater than an average crystallite size of the alpha-type SiC, and the SiC matrix composite material has a porosity of no greater than 20% by volume.

The carbon fiber precursor contains a crosslinked acrylamide-based polymer and has a gel fraction of 5% or more.