A review of the properties of the oxide ceramic fibers that are available at the present time discloses that they cannot meet many of the projected requirements for reinforcement of high-temperature composites requiring stable strength and stiffness properties and resistance to creep at high temperatures, (e.g. > 1200°C), for extended periods of time. New fibers of selected compositions will be necessary to satisfy these needs.

The controlled pyrolysis of precursor fibers has been shown to be a useful process for the fabrication of both oxide and nonoxide high-performance fibers for structural applications. It is a uniquely versatile process in that virtually any composition that can be compounded in a fiberizable precursor batch can be pyrolyzed to form continuous inorganic fibers. However, the preparation of fibers sufficiently handleable for use and possessing properties that would classify them as high-performance fibers requires sophisticated process control procedures tailored to each composition and adjusted for the precursor materials used. Survival of the filament form through pyrolysis does not necessarily guarantee a resultant high-quality fiber because it must undergo further heat treatment with associated solid-state reactions, crystal growth, and structural changes.

Fundamental studies on progressive microstructural changes that take place during the pyrolysis process as well as during sintering and densification of the resulting inorganic fiber would facilitate development of advanced high-performance inorganic fibers not now available. Especially important is the development of methods for stabilization of microstructures so as to prevent or minimize property changes during high-temperature applications.

The Chemical Conversion Of A Precursor Fiber (Ccpf) Is A Versatile But Not Very Well Known Fiber-Making Technology Used By Researchers From The Early 1960s To The Mid-1970s To Develop A Number Of Interesting Refractory Fibrous Materials. As The Name Of The Process Implies, The Method Invokes The Conversion Of One Fiber Into Another By Reacting The Precursor Fiber With The Proper Reactants Under Precisely Controlled Conditions. Thus, The Difficult Task Of Forming The Refractory Fiber Directly Is Bypassed. Instead, Effort Is Focused On Dealing With A Chemical Problem To Accomplish Conversion Of An Existing Fiber Into Another.

The Success Of This Method Depends On Two Important Factors:

• Selection Of Available Fiber As Precursor For The Reaction.

• Control Of Reaction Parameters To Facilitate The Reaction Between The Reactants And The Precursor Fiber.

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)