This may mean beginning with emergent CPC systems and applications that do not require either the highest level of structural performance or maximum temperature capability, nor that are optimum in their payoff, but instead serve a useful purpose, are cost effective, and give the opportunity to demonstrate reliable production methods, non-destructive evaluation (NDE) techniques, and design principles. This approach would allow a broader range of applications to be found for CMCs, and it would offer the potential to further support the overall technology base.

Carbon-carbon (C-C) composites are structures in which both the matrix and the reinforcement are carbon. They offer many advantages in high-temperature applications over composites fabricated with other matrix materials. The unique high-temperature mechanical property retention of C-C composites (in excess of 2200°C) and their low density (1.5 to 2.0 g/cc) make them useful at high temperatures (i.e., above 1350°C in some cases and above 1700°C for short-time, limited-use application). For continuously reinforced C-C composites, it is the mechanical properties of the carbon-graphite fibers that dominate the C-C composite properties, and it is the high-temperature capability of the carbon matrix that allows one to take advantage of the fiber properties at elevated temperatures, where most metal matrices have melted or polymer matrices have decomposed or melted.

The major drawback of C-C composites is lack of oxidation resistance. Carbon's oxidation rate increases dramatically above 600°C, and unless an oxygen barrier or inhibitor is applied to the C-C composite or its constituents, operational time above this temperature is limited. Another disadvantage of high-performance C-C composites is fabrication cost, which is a result of the high fiber cost, the long processing times, the many fabrication steps needed to achieve the desired composite properties, and the expense associated with the use of high-temperature processing equipment. However, in many applications where C-C composites are considered for use, government specifications dictate the use of expensive manufacturing methods or preclude the use of any other matrix.

A continuous fiber C-C composite is fabricated by first forming a ''preform'' of carbon-graphite fibers either by weaving a fabric that is used to build up a structural shape (involutes, rolled fabric, pierced fabric, etc.), by weaving straight fibers in multidimensions, or by braiding. This preform is then densified; that is carbon is added to the interstices of the fiber preform to become the matrix of the composite. Formation of the carbon matrix can be accomplished by a number of methods: conversion of liquid resin or liquid pitch precursors, gaseous or CVI, or combinations of these to achieve desired physical properties. Discontinuously reinforced C-C may be fabricated by starting with a carbon fiber felt and densifying by CVI or by mixing carbon fibers or whiskers in a carbon-forming precursor and then pyrolyzing and graphitizing.