composite insertions: structural, dimensionally stable, and thermal management components. The relatively low carbon-matrix modulus of elasticity causes very little matrix contribution to the C-C composite thermal expansion coefficient, and thus a zero or slightly negative thermal expansion coefficient of the composite can be obtained by using carbon fibers with these same properties.

It has been shown that highly graphitic fibers are resistant to shrinkage under intense neutron radiation. This attribute, together with other properties of high-temperature strength, toughness, and low nuclear cross section, makes highly graphitized C-C composites applicable for nuclear power plant applications.

Applications that could potentially be exploited for economic considerations are in high-temperature processing of materials. Some examples include containers for molten metal, high-temperature bearings in steel mills and chemical processing plants.

Oxidation is the most critical problem to overcome if C-C composites are to be widely used in a variety of applications. Composite surface coatings can provide protection, but to provide for a more gradual degradation in the performance of the composite in the event of a breech in the coating, internal oxidation resistance must be designed into the C-C composite substrate. The high cost of C-C composites is also a major issue and must be addressed on many fronts. The major contributors to the high costs are fiber cost, preforming costs, and densification costs. The technical issues involved are discussed further in Chapter 4.

As pointed out earlier, composites—especially advanced composites—are used primarily in structural and semistructural applications for which the dominant considerations are mechanical properties, such as stiffness, static strength, and resistance to fatigue, creep, and creep rupture. However, there are many applications for which other physical properties, alone or in combination with mechanical properties, dominate the selection process. These physical properties include electrical conductivity, thermal conductivity, coefficient of thermal expansion (CTE), dielectric properties and magnetic characteristics. Although there are currently many applications for which these properties are critical factors in the choice of materials, their unique properties in composites have not been fully exploited. This chapter considers current and potential applications for which nonstructural physical properties are key requirements and examines the needs for new or improved fibers to exploit these properties.

Front Matter (R1-R16)

Executive Summary, Conclusions, and Recommendations (1-8)

1 High-Performance Synthetic Fibers for Composites (9-20)

2 High-Performance Fiber Materials: Applications, Needs, and Opportunities (21-48)

3 Fiber-Forming Processes: Current and Potential Methods (49-102)

4 Important Issues in Fiber Science/Technology (103-108)

5 Important Policy Issues (109-118)

Glossary of Terms (119-126)

Appendix (127-129)