NASA Reference Publication, Issue 1254National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1977 - Astronautics |
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Page 19
... Solution Spinning of PAN Precursor Fibers 20 Melt - Assisted Spinning of PAN Precursor Fibers 22 Heat Treatment of PAN Precursor Fibers 23 Oxidation of PAN Precursor Fibers 23 Carbonization and Graphitization 24 Manufacture of Rayon ...
... Solution Spinning of PAN Precursor Fibers 20 Melt - Assisted Spinning of PAN Precursor Fibers 22 Heat Treatment of PAN Precursor Fibers 23 Oxidation of PAN Precursor Fibers 23 Carbonization and Graphitization 24 Manufacture of Rayon ...
Page 20
... solution spinning techniques . Solution Spinning of PAN Precursor Fibers Figure 2 shows the process schematic of a typical solution spinning process ( ref . 2 ) . In this process , the copolymer first is dissolved in a suitable solvent ...
... solution spinning techniques . Solution Spinning of PAN Precursor Fibers Figure 2 shows the process schematic of a typical solution spinning process ( ref . 2 ) . In this process , the copolymer first is dissolved in a suitable solvent ...
Page 22
... solution spinning , the polymer solution is extruded into a hot gas environment . In this case , the temperature and composition of the gas must be carefully monitored to control the rate of solvent evaporation and , thus , the ...
... solution spinning , the polymer solution is extruded into a hot gas environment . In this case , the temperature and composition of the gas must be carefully monitored to control the rate of solvent evaporation and , thus , the ...
Page 26
... solutions , or electrolytically etching the fiber . The principal goal of this process step is to increase the interfacial ... solution and then treated with CS2 to form cellulose xanthate . This soluble derivative of cellulose then is ...
... solutions , or electrolytically etching the fiber . The principal goal of this process step is to increase the interfacial ... solution and then treated with CS2 to form cellulose xanthate . This soluble derivative of cellulose then is ...
Page 28
... mesophase precursors have certain characteristics of both mixtures and solutions : they soften over a range of temperatures and orient under an applied stress . CH2 CH2 CH2 Molecular weight = 1178 C / H 28 CC Materials and Composites.
... mesophase precursors have certain characteristics of both mixtures and solutions : they soften over a range of temperatures and orient under an applied stress . CH2 CH2 CH2 Molecular weight = 1178 C / H 28 CC Materials and Composites.
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3-D braid alignment anisotropic applications approximately basal planes bonding borate borate glasses carbon fibers ref carbon matrix Carbon-Carbon Composites CC composites CC materials Chemical Vapor Deposition Composite Materials compressive strength cracks crystallites densification density effective elastic modulus fiber architecture fiber axis fiber bundle fiber surface fiber-reinforced filament geometry graphite heat treatment high modulus high temperatures high-performance impregnation increase interface isotropic knit laminate layer planes matrix matrix composites matrix material mechanical properties mesophase pitch method microcracks microstructure noncircular outer coating oxidation oxygen PAN fibers PAN precursor fiber PAN-based carbon fibers PAN-based fibers percent phenolic pitch matrix pitch-based carbon fibers pitch-based fibers polymer preform pressure produce pyrolysis pyrolytic carbon rayon reinforced resin result shear strength shown in figure SiO2 stiffness structure substrate techniques tensile modulus tensile strength thermal expansion thermoset thickness transverse unit cell weave woven yarn
Popular passages
Page 102 - Processing-Proceedings of 1987 International SAMPE Metals Conference, August 18-21, 1987. Bibliography A. Chou, TW; and Ko, FK: Textile Structural Composites . Elsevier, 1988. B. Hearle, JWS; Grosberg, P.; and Backer, S.: Structural Mechanics of Fibers, Yarns nd Fabrics. John Wiley & Sons, 1969. C. Kaswel, ER: Wellington-Sears Handbook of Industrial Textiles. West Point Pepperell, Inc., 1963. D. Klein, AJ: Which Way to Weave. Adv. Mater. & Process., vol. 2, no. 3, 1986, pp. 40-43.
Page 72 - On the basis of structural integrity and fiber linearity and continuity, fiber architecture can be classified into four categories: discrete, continuous, planar interlaced (2-D), and fully integrated (3-D) structures. In table I, the nature of the various levels of fiber architecture is summarized (ref.
Page 8 - In the thermal gradient technique (fig. 9), the part to be infiltrated is supported by a mandrel that is inductively heated. Therefore, the hottest portion of the substrate is the inside surface, which is in direct contact with the mandrel. The outer surface of the low-density substrate is exposed to a cooler environment and results in a temperature gradient through the substrate thickness. Surface crusting is eliminated because the deposition rate is greater on the heated fibers near the mandrel,...
Page 14 - Bokros, JC: Deposition, Structure, and Properties of Pyrolytic Carbon.
Page 84 - Brochier (ref. 12), and SEP (ref. 13) and in Japan by Fukuta of the Research Institute for Polymers and Textiles (refs. 14 and 15). The structural geometries resulting from the various processing techniques are shown in figure 15 (ref. 16). Figures 16(a) and 16(b) show the single bundle XYZ fabrics in a rectangular and cylindrical shape. Figure 16(c) demonstrates the multiple-yarn bundle possibilities in the various directions; figure 16(d) shows the multidirectional reinforcement in the 3-D structure...
Page 95 - In this way, four inclined, unidirectional laminae formed a unit cell. Using classical laminate theory, the elastic moduli then can be expressed in terms of the laminae properties. From the preform processing science aspect, Ko et al. (ref. 45) developed a fabric geometric model (FGM) based on the unit cell geometry shown in figure 26. The stiffness of a 3-D braided composite was considered to be the sum of stiffnesses of all its laminae. The unique feature of the FGM is its ability to handle 3-D...
Page 73 - A discrete fiber system such as a whisker or fiber mat has no material continuity; the orientation of the fibers is difficult to control precisely, although some aligned discrete fiber systems have recently been introduced. The structural integrity of the fibrous preform is derived mainly from inter-fiber friction. The strength translation efficiency, or the fraction of fiber strength translated to the non-aligned fibrous assembly of the reinforcement system, is quite low.
Page 88 - The major distinctions of these fabrics are the linearity of the bias yarns, the number of axes, and the precision of the stitching process.
Page 251 - ... to 1 14). Figure 14 shows the type of forced-flow thermal gradient arrangement currently being used for rapid CVI within deposition chambers at General Atomics. Temperature Limitations Current Coatings Although actual temperature limitations on the coatings currently being used for CC oxidation protection will vary depending on specific operating conditions and component performance requirements, general guidelines can be established based on experimental observations and the known thermochemical...