An attempt has been made to review and analyze the developments made during last few decades in the field of high performance carbon fibers. The focus is primarily on high technology sector, which includes aerospace and nuclear engineering or other areas, where the large scale use of carbon fibers is driven by maximum performance and not by cost factors. Some specific areas for future research have been identified and suggested in order to minimize the gap between theoretical and practically realized tensile strengths and other mechanical properties of carbon fibers. The technical and commercial breakthrough for high-performance carbon fibers started in the late 1960s af-ter introduction of the PAN process, which turned out to be more economical due to higher carbon yields, which is 50 % against 30 % for rayon, and simpler fab-rication process. PAN based fibers also had su-perior physical properties compared to rayon based fibers. PAN fiber is today recognized as the most important and promising precursor for manufacture of high strength carbon fibers. Later carbon fibers were also prepared from pitch, a very cheap precursor. The most commonly used pitches are those obtained from petroleum, asphalt, coal tar, and PVC. The properties of pitch carbon fibers are generally inferior to PAN car-bon fibers because, if not specially treated, the pitches are usually isotropic before pyrolysis, and the isotropy is maintained in the fibers unless the orientation of the larger planes is carried out under tension during the high temperature treatment, between 2000 deg C and 3000 deg C. Al-though this process gives the carbon fibers excellent performance properties, it is very expensive. This expensive stretching treatment can be avoided by using mesophase pitches, which are liquid crys-talline in nature. The high degree of molecular orienta-tion of as-spun mesophase pitch fibers allows it, unlike PAN, to develop a truly graphitic crystalline structure during the carbonization/graphitization step. Hence ultra high modulus carbon fibers are now produced from mesophase pitches.


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    Titel :

    Carbon fibers for composites


    Weitere Titelangaben:

    Überblick über Kohlenstoffasern für Verbundwerkstoffe


    Beteiligte:
    Chand, S. (Autor:in)

    Erschienen in:

    Journal of Materials Science ; 35 , 6 ; 1303-1313


    Erscheinungsdatum :

    2000


    Format / Umfang :

    11 Seiten, 7 Bilder, 1 Tabelle, 151 Quellen




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Print


    Sprache :

    Englisch