High tensile strength, high young's modulus carbon fiber having

Abstract

High tensile strength, high Young's modulus carbon fiber, free from holes and voids having a statistical probability of holes detected by a standard plasma etching test of less than about 2%, a tensile strength of at least about 150 kg/mm.sup.2 and a Young's modulus of at least about 15 .times. 10.sup.3 kg/mm.sup.2. The carbon fiber has excellent homogeneity of internal structure and excellent reliability as a composite material. A process is provided for producing a high performance, high quality carbon fiber having excellent productivity and operability and requiring only a short time for oxidation. The process comprises converting an organic polymeric fiber (preferably an acrylic fiber) to an oxidized fiber, comprising repeatedly bringing said fiber into contact with the surface of a heated body such as a heated roll or heated plate at about 200.degree. - 400.degree. C in the presence of an oxidizing gas for a contact time per single contact of said fiber with the surface of the heated body of less than about 1 second, and heating the resulting oxidized fiber in an atmosphere of an inert gas at a temperature of at least about 800.degree. C to thereby convert the oxidized fiber to a carbon fiber.