Abstract: A graphitized fiber heat-treated at a temperature higher than 2300.degree. C. in an inert atmosphere, of which oxidation weight reduction rate A in dry air at 650.degree. C. is in the range defined by the equation (1), of which BET specific surface area S determine by nitrogen or krypton adsorption technique at -196.degree. C. is in the range defined by the equation (2), and of which pore volume determined by the carbon dioxide adsorption technique at 25.degree. C. is 0.001 ml/g or less: ##EQU1## where, A is the oxidation weight reduction rate in dry air at 650.degree. C. in min.sup.-1S is the specific surface area determine by nitrogen or kypton adsoprtion technique at -196.degree. C. in m.sup.2 g.sup.-1D is the mean monofilament diameter of the graphitized fiber in .mu.m and .rho. is the density of the graphitized fiber in gcm.sup.-3.

Abstract: In a method of producing mesophase pitch based carbon fibers, including the steps of melt-spinning a mesophase pitch through a nozzle (1) having at least one pair of a counter-bore (2) and a circular capillary (3) to form a pitch fiber and subjecting the pitch fiber to an infusible treatment, a carbonization treatment, and if necessary, a graphitization treatment, to form a carbon fiber, the nozzle has a degree of asymmetry .phi. of from 0.1 to 0.9, .phi. being defined by the following equation .phi.=S.sub.A /S.sub.B, wherein S.sub.A is an area of an inscribed circle in a contour of the cross-section of the counter-bore, which circles is perpendicular to the nozzle axis and has a center on the axis of the capillary and inscribed and S.sub.B is a total area of the cross-section of the counter-bore.

Abstract: A mesophase pitch suitable for carbon products, particularly for carbon fibers, which has a mesophase content of at least 40%, preferably at least 60%, and a larger mesophase domain, is produced by adding at least one part by weight of at least one of an alcohol and a phenol to 100 parts by weight of heavy bitumens, subjecting the resulting mixture to pretreatment by heating at least at 250.degree. C., and then subjecting the pretreated mixture to heat treatment until mesophases are formed.

Abstract: In mixing coal tar and/or coal tar pitch with aromatic and aliphatic solvents at atmospheric pressure and at a temperature between 15.degree. C and 140.degree. C to prepare a raw material for the manufacture of needle coke, the mixing ratio of the aromatic and aliphatic solvents and their quantities of addition to the coal tar and/or coal tar pitch are adjusted so that insoluble substances precipitate in a pitch zone. A supernatant obtained by separating the insoluble substances is distilled, and hydrocarbons consisting substantially of aromatic compounds and freed of the insoluble substances are obtained. Then the hydrocarbons are used as the raw material for the manufacture of needle coke.

Abstract: A process for preparing needle coal pitch coke by mixing coal tar and/or coal tar pitch with aromatic and aliphatic solvents under atmospheric pressure and at temperatures between 15.degree. C and 140.degree. C. The mixing ratio of the aromatic and aliphatic solvents and their quantities of addition to coal tar and/or coal tar pitch are adjusted so that insoluble substances precipitate in a zone selected from the group consisting of a slurry zone and a crystal zone. By distilling a supernatant solution obtained by separating the insoluble substances occurring in the slurry or crystal zone, hydrocarbons consisting substantially of aromatic compounds and free of the insoluble substances are obtained. The obtained hydrocarbons are processed into coke.