Abstract: Fibers having a high degree of flexibility and handleability are produced by oxidizing fibers spun from a carbonaceous pitch which has been transformed, in part, to a liquid crystal or so-called "mesophase" state to an oxygen content of from 17 per cent by weight to 30 per cent by weight. Because of their strength and handleability, these highly-oxidized fibers can be easily processed at high speeds by means of conventional yarn-transport systems, and readily woven or knit into cloth. Such cloth may then be heat treated to produce carbon or graphite cloth.

Abstract: High modulus, high strength carbon fibers, having a highly oriented structure characterized by the presence of carbon crystallites preferentially aligned parallel to the fiber axis, are produced from carbonaceous pitches which have been transformed, in part, to a liquid crystal or so-called "mesophase" state. When heated to graphitizing temperatures, these fibers develop the three-dimensional order characteristic of polycrystalline graphite.

Abstract: An improved process for producing carbon fibers from pitch which has been transformed, in part, to a liquid crystal or so-called "mesophase" state. According to the process, pitch of a given mesophase content, suitable for producing carbon fibers, is produced in substantially shorter periods of time than heretofore possible, at a given temperature, by subjecting the pitch to reduced pressure during formation of the mesophase.

Abstract: Mesophase pitches wherein the planes of the mesophase portions of the pitch are substantially aligned in a single parallel direction, and the c-axes of said planes are substantially aligned in a single parallel direction, are produced by subjecting a mesophase pitch in its molten state to rotational motion relative to a surrounding magnetic field about an axis perpendicular to the direction of that field.

Abstract: A boron nitride crucible, suitable for the vaporization of aluminum, having a multi-walled structure comprising an outer wall and a thinner inner wall weakly bonded to the thicker outer wall. Because of this structure, the crucible is considerably more flexible than conventional single-walled crucibles and exhibits substantially improved thermal cycling characteristics and longer life. The crucible is produced by depositing pyrolytic boron nitride upon a mandrel having the shape of the desired crucible at a temperature of from about 1850.degree. C. to about 2100.degree. C. until a first layer of boron nitride of suitable thickness has been produced, interrupting the deposition of boron nitride upon the mandrel and lowering the temperature to below 1750.degree. C., and then depositing additional boron nitride upon the mandrel at a temperature of from about 1850.degree. C. to about 2100.degree. C. to produce a second outer layer of boron nitride having a thickness greater than that of the inner layer.

Abstract: An improved process for producing carbon fibers from pitch which has been transformed, in part, to a liquid crystal or so-called "mesophase" state. According to the process, carbon fibers are produced from pitch wherein the mesophase content of the pitch has been formed while agitating the pitch so as to produce a homogeneous emulsion of the immiscible mesophase and non-mesophase portions of the pitch. Mesophase pitches prepared in this manner have been found to possess a lesser amount of high molecular weight molecules in the mesophase portion of the pitch and a lesser amount of low molecular weight molecules in the non-mesophase portion of the pitch, and thus a smaller differential between the average molecular weights of the mesophase and non-mesophase portions of the pitch, than mesophase pitches having the same mesophase content which have been prepared in the absence of such agitation.BACKGROUND OF THE INVENTION1.

Abstract: An improved process for producing carbon fibers from pitch which has been transformed, in part, to a liquid crystal or so-called "mesophase" state. According to the process, pitch of a given mesophase content, suitable for producing carbon fibers, is produced in substantially shorter periods of time than heretofore possible, at a given temperature, by passing an inert gas through the pitch during formation of the mesophase.

Abstract: Improved fuel cell electrodes produced by spinning a carbonaceous pitch having a mesophase content of from about 40 per cent by weight to about 90 per cent by weight to form carbonaceous pitch fiber; disposing staple lengths of the spun fiber in intimately contacting relationship with each other in a non-woven fibrous web; heating the web produced in this manner in an oxidizing atmosphere to thermoset the fibers to an extent which will allow the fibers to maintain their shape upon heating to more elevated temperatures; heating the web containing the thermoset fibers to a carbonizing temperature in an oxygen-free atmosphere so as to expel hydrogen and other volatiles; impregnating the web with a hydrophobic resin dispersion; compressing the impregnated web to remove excess fluid and form a thin, paper-like sheet; drying the compressed sheet, and heating it at a temperature sufficiently elevated to cause the hydrophobic resin impregnant to fuse and bond the fibers of the web together so as to increase the struc

Abstract: An improved process for producing carbon fibers by the pyrolysis of polyacrylonitrile fibers wherein the extended heat treatment heretofore required in order to stabilize the fiber structure so that it may be carbonized is completed in substantially shorter periods of time by effecting stabilization in an atmosphere containing both hydrogen chloride and oxygen. After the fibers have been thermally stabilized in this manner, they may be rapidly carbonized in times as short as one-half minute.