Chapter 64. NDE of Structural and Functional Carbon-Carbon Composites after First Carbonization
- 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
Vaidya, U. K., Mahfuz, H. and Jeelani, S. (1994) NDE of Structural and Functional Carbon-Carbon Composites after First Carbonization, 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.ch64
- Published Online: 28 MAR 2008
- Published Print: 1 JAN 1994
Print ISBN: 9780470375327
Online ISBN: 9780470314500
- first carbonization;
In the processing cycle of carbon-carbon (C/C) composites, transition of the precursor polymer matrix to a carbon matrix takes place at the stage of first carbonization. Matrix microcracking, interfacial debonding and development of distributed porosity are some consequences of first carbonization. The extent of these happenings are dependent on factors such as material precursor systems and time/temperatures of carbonization. These factors, in turn influence the resulting physical, mechanical and thermal properties of the final (after number of impregnation cycles) C/C composites. A key to assessing and optimizing these properties of the final material is to successfully define nondestructive evaluation (NDE)-microstructure-process relationships for different material precursor systems at the stage of first carbonization. Here such a study is undertaken through a systematic consideration of structural and functional fiber reinforced phenolic matrix precursor material systems. Structural composite precursor systems consisted of woven fabric architectures, such as plain, satin and stretch broken, while the functional systems included nonwoven thermal bonded carbon fiber. These materials were subjected to ultrasonic and vibration NDE at their as-cured and carbonized matrix stages. Ultrasonic testing included C-scans and velocity measurements, while material damping and resonance frequency were the vibration parameters that were considered. NDE parameters from these methods were correlated with various mechanisms ensuing first carbonization.