1. Microstructure Studies of Carbon-Carbon Composite Materials
Kei Yamamoto
Purdue University
Advisor: Prof. Alex King

2. Presentation Outline
Background information on Carbon-Carbon Composites
Optical Microscopy images
X-ray diffraction results
SEM images
Conclusions
Future Work

3. What are Carbon-Carbon Composites?
Amorphous carbon matrix composite
Carbon matrix reinforced by graphitic carbon fibers
First developed in 1958, but not intensively researched until the Space Shuttle Program (for insulation)

4. How are Carbon-Carbon composites made?
First carbon fibers are made by pyrolizing Poly-acrylo-nitrile (PAN) fibers
Pyrolized fibers then woven into the desired pattern
Spaces between the fibers are filled by Chemical Vapor Deposition (CVD)

5. Properties of Carbon-Carbon Composites
Outstanding durability at temperatures over 2000ºC
Low coefficient of thermal expansion
Great thermal shock resistance
High strength
Low weight
High melting point
Corrosion resistant
Expensive
Long time to manufacture (weeks to months)

6. Properties of Carbon-Carbon

8. Uses of Carbon-Carbon Composites
Aircraft, F-1 racing cars and train brakes
Space shuttle nose tip and leading edges
Rocket nozzles and tips

9. Original goals of my project
To determine how the microstructure of the carbon-carbon composites affect the properties of aircraft brakes
To find out the best methods to determine porosity and fiber alignment to be used as quality control tests

10. Sample 1

11. Sample 2

12. Sample 3

13. Sample 4

14. Optical Microscopy
Sample 1:

15. Optical Microscopy
Sample 2:

16. Optical Microscopy
Sample 3:

17. X-ray Diffraction Results

18. X-ray Diffraction Results

19. X-ray Diffraction Results

20. X-ray Diffraction Results

21. Microtome Cuts thin slices (microns thick) of your specimen
Specimen must be soft
Beem Capsule
Microtome

22. Microtomy Result

23. Sample #
Mass Before Heating
Mass After Heating
% Mass Change 1 g % 2 g g
0.0303% 3 g g
2.1699% 4 g g %

24. SEM Images
Sample 1:

25. SEM Images
Sample 2:

26. SEM Images
Sample 3:

27. SEM Images
Sample 4:

28. Conclusions
Crystallinity of carbon fibers varies considerably between specimens
In samples 2, 3 and 4 the amorphous carbon matrix and carbon fibers are not well bound together, thus matrix is not providing any benefits to the structure
In sample 1 amorphous carbon matrix and carbon fibers are bound together but it is not inter-grown together, thus matrix is still not providing any benefits to the structure
Carbon was only deposited on the surface in one of the specimens: amorphous carbon nucleation is found only very rarely on the fiber surfaces in this specimen

29. Future Work
Improvement of the sectioning process to retain shell and core structure of carbon-carbon composite
Refine techniques for embedding the material
Develop a capacity for thin section specimens for transmitted light microscopy and TEM
Routine SEM and XRD
Relate results to processing the samples have been exposed to

30. Acknowledgements
Prof. Alex King
Indiana 21st Century fund
Honeywell

31. Questions?