Chapter 24. Mechanical Behaviour of a 3-D Braided, Continuous SiC Fibre- Reinforced / CVI SiC Matrix Composite at Ambient and Elevated-Temperatures
- John B. Wachtman Jr.
Published Online: 28 MAR 2008
Copyright © 1994 The American Ceramic Society
Proceedings of the 18th Annual Conference on Composites and Advanced Ceramic Materials - A: Ceramic Engineering and Science Proceedings, Volume 15, Issue 4
How to Cite
Jenkins, M. G., Piccola, J. P., Mello, M. D., Lara-Curzio, E. and Wereszczak, A. A. (1994) Mechanical Behaviour of a 3-D Braided, Continuous SiC Fibre- Reinforced / CVI SiC Matrix Composite at Ambient and Elevated-Temperatures, in Proceedings of the 18th Annual Conference on Composites and Advanced Ceramic Materials - A: Ceramic Engineering and Science Proceedings, Volume 15, Issue 4 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470314500.ch24
- Published Online: 28 MAR 2008
- Published Print: 1 JAN 1994
Print ISBN: 9780470375327
Online ISBN: 9780470314500
- draulic grips
Three-dimensionally reinforced continuous-fibre ceramic matrix composites (CFCCs) were fabricated from preforms of braided SiC fibre (Nicalon™) tows that had been coated with 0.4-μm thick layer of pyrolytic graphite. A hybrid infiltration process of CVI and polymer precursor processing was used to promote the matrix and consolidate the composite. The as-fabricated CFCCs were composed of -35 vol% fibre, -40 vol% matrix and -25 vol% residual porosity. Densities and elastic constants were determined prior to testing. Straight-sided and contoured coupons were tested in uniaxial tension and compression at 20 and 1000°C. End tabs comprised of shaped potted-epoxy were used on all specimens to prevent crushing of the gripped specimen sections in the water-cooled, face-loaded hydraulic grips. Three- and four-point flexure tests were also conducted at 20 and 1000°C. Linear stress-strain responses to well-defined proportional limits (-75 MPa) were observed for tension and flexure at both temperatures. Nonlinear stress-strain behaviour was observed beyond the proportional limit up to fracture at ultimate strengths in tension on the order of 175-200 MPa for 20°C and 100 MPa for 1000 C. SEM fractography revealed fibre pullout for the 20°C tests and evidence of brittle fracture due to environmental degradation for the 1000°C tests.