17. Humidity and Frictional Performance of C/C Composites

  1. Manuel E. Brito,
  2. Peter Filip,
  3. Charles Lewinsohn,
  4. Ali Sayir,
  5. Mark Opeka and
  6. William M. Mullins
  1. Milan Krkoska and
  2. Peter Filip

Published Online: 26 MAR 2008

DOI: 10.1002/9780470291283.ch17

Developments in Advanced Ceramics and Composites: Ceramic Engineering and Science Proceedings, Volume 26, Number 8

Developments in Advanced Ceramics and Composites: Ceramic Engineering and Science Proceedings, Volume 26, Number 8

How to Cite

Krkoska, M. and Filip, P. (2005) Humidity and Frictional Performance of C/C Composites, in Developments in Advanced Ceramics and Composites: Ceramic Engineering and Science Proceedings, Volume 26, Number 8 (eds M. E. Brito, P. Filip, C. Lewinsohn, A. Sayir, M. Opeka and W. M. Mullins), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470291283.ch17

Author Information

  1. Southern Illinois University at Carbondale, SIUC 1230 Lincoln Dr. Carbondale, IL 62901–4343

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 2005

ISBN Information

Print ISBN: 9781574982619

Online ISBN: 9780470291283

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Keywords:

  • carbon;
  • energy;
  • amorphous;
  • moisture;
  • oxygen

Summary

This paper focuses on friction and wear of the carbon-carbon composite materials tested at different simulated landing energy and humidity conditions. The strong influence of humidity was visible at the low landing energy conditions. Temperature on the friction surface is insufficient for the evaporation of moisture, and the average coefficient of friction is low (μ = 0.15). At higher energy, the average μ increases to 0.4. However, the friction becomes unstable and depending on time. Similar frictional response was detected for both, 2D and 3D materials, however the effect is more pronounced in 3D composites. Wear of 2D material is sensitive to the level of the moisture and less sensitive to energy dissipated in friction process. As the humidity increases, wear of 2D material decreases proportionally. Wear data of 3D material demonstrated considerable sensitivity to humidity and to braking energy levels. At low energy braking simulations, wear of 3D composite is significantly higher compared to 2D samples. Opposite tendency was observed at 100% normal landing energy (NLE) simulations and wear is similar for 3D and 2D tested at 50% NLE. Microstructural studies showed that the friction layer was developed on the rubbing surface during all braking simulations. The proportion of the area covered by the friction layer is markedly influencing the frictional properties of C/C composite materials. TEM analysis revealed that at small energies, the friction layer was always amorphous. At highest energy simulations, a mixture of amorphous and highly crystalline carbons was detected in the friction layer. No direct correlation between crystal order of friction film and frictional performance was found.