Chapter 78. Continuous Fabrication of SiC Fiber Tows by CVD
- John B. Wachtman Jr.
Published Online: 28 MAR 2008
Copyright © 1993 The American Ceramic Society
Proceedings of the 17th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 14, Issue 7/8
How to Cite
Lackey, W. J., Hanigofsky, J. A., Freeman, G. B., Hardin, R. D. and Prasad, A. (1993) Continuous Fabrication of SiC Fiber Tows by CVD, in Proceedings of the 17th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 14, Issue 7/8 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470314180.ch78
- Published Online: 28 MAR 2008
- Published Print: 1 JAN 1993
Print ISBN: 9780470375266
Online ISBN: 9780470314180
- silicon carbide fiber;
- thermal expansion;
The feasibility of preparing small diameter, high strength, thermally stable silicon carbide fiber tows by the continuous chemical vapor deposition of SiC onto carbon fiber tows was experimentally evaluated. A 5 m̈m diameter carbon substrate with a 5 m̈m SiC coating thickness yields a fiber that is 89 vol% SiC. Calculations of bending stresses and stresses caused by thermal expansion mismatch between the substrate and coating were used to evaluate the influence of coating thickness and substrate fiber diameter and type, e.g., T-50 versus T-300 carbon fiber.
Statistically designed and analyzed processing studies have quantitatively shown the influence of key CVD process variables (temperature, pressure, and flow rates of CH3SiCl3 and H2) on fiber attributes such as coating thickness and uniformity, surface roughness, percent agglomeration, and strength. Emphasis was given to conceiving and evaluating various fiber spreading devices in order to enhance coating uniformity and to minimize filament agglomeration within a tow. Uniform coating and fiber tensile strengths in excess of 2 GPa were achieved.