handbook of carbon, graphite, diamond and fullerenes

30
Applications of Carbon Fibers 213
2D Carbon/Carbon
IN-100 (Nickel Base)
Single Crystal
Superalloy
500 1000 1500
Temperature,°C
2000
Figure 9.4. Specific strength of carbon-carbon and refractory alloys as a function
of temperature.' 37 l
4.4 Carbon-Carbon Applications
Table 9.8 lists some of the present applications of carbon-carbon.
These are either in production or in the development stageJ 28 '! 381
Aircraft Brakes. By far the largest volume application of carboncarbon
is found in aircraft brakes. Carbon-carbon brakes offer a lifelong,
lightweight alternative to steel brakes. For instance, the weight saving on
the Boeing 767 is 395 kg with double the number of landings per overhaul.
Since the coefficient of friction remains constant with temperature, brakes
do not fade. A typical fabrication process includes carbonizing PAN-fiber
fabrics to 1000°C, cutting the fabric to shape, impregnating with a polymer,
carbonizing, and densifying by CVD by the decomposition of natural gas at
low-pressureJ 29 ' A carbon-carbon brake assembly is shown in Fig. 9.5.
Cost of Carbon-Carbon. Because of the long and involved processing,
the cost of carbon-carbon is high and estimated at over $200/kg for
industrial parts and considerably more for some aerospace applications.