handbook of carbon, graphite, diamond and fullerenes

4.0 CARBON-CARBON
4.1 General Characteristics of Carbon-Carbon
Applications of Carbon Fibers 209
The carbon-fiber/polymer composites reviewed in the previous section
have excellent mechanical properties but limited temperature resistance.
Maximum operating temperature is presently - 370°C (Table 9.2).
These composites cannot meet the increasingly exacting requirements of
many aerospace applications which call for a material with low density,
excellent thermal-shock resistance, high strength, and with temperature
resistance as high or higher than that of refractory metals or ceramics.
These requirements are met by the so-called "carbon-carbon" materials.
Carbon-carbon refers to a composite comprising a carbon-fiber reinforcement
and a carbon matrix, in other words an all-carbon material.
Carbon-carbon was developed in the early 1960's in various programs
sponsored by the United States Air Force.t 17 ^ 181 Some of the early
applications of carbon-carbon were in nose tips and heat shields of reentry
vehicles. f19 K 20! Carbon-carbon is now a major structural material, not only
in aerospace, but also in many non-military applications.
Carbon-carbon has many common features with the various materials
already reviewed in previous chapters such as molded carbon and graphite,
polymeric carbon and pyrolytic graphite. It is often considered as a
refractory version of the carbon-fiber/ polymer composites.
Carbon-carbon has a major disadvantage, that is poor oxidation
resistance and efforts to solve the problem have met with only limited
success so far. A solution will have to be found to this Achilles' heel before
the material can achieve its full potential.
4.2 Carbon-Carbon Composition and Processing
Carbon-Fiber Network. Rayon-based carbon fibers were used in the
early development of carbon-carbon and are still used as carbon felt. PANbased
fibers are now used extensively and pitch-based fibers are under
investigation.! 211 The selection of the carbon-fiber architecture is determined
by the application and include felt, short (chopped) fibers, continuous
filament such as small-tow T-300 fiber, filament winding or tape-layup, and
3D structures (see Sec. 2.0 above). The effect of carbon-fiber type and
architecture is reviewed in Refs. 22 and 23. The effect of carbon-fiber