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

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

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)

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) http://www.fibermaterialsinc.com/frSW.htm

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)

Properties of Carbon-Carbon http://www.hitco.com/products/corrosion/chemical/index.html

http://www.hitco.com/products/corrosion/chemical/index.html

Uses of Carbon-Carbon Composites http://www.fibermaterialsinc.com/frSW.htm Aircraft, F-1 racing cars and train brakes Space shuttle nose tip and leading edges Rocket nozzles and tips http://www.futureshuttle.com/conference/ThermalProtectionSystem/Curry_73099.pdf http://www.fibermaterialsinc.com/frSW.htm

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

Sample 1

Sample 2

Sample 3

Sample 4

Optical Microscopy Sample 1:

Optical Microscopy Sample 2:

Optical Microscopy Sample 3:

X-ray Diffraction Results

X-ray Diffraction Results

X-ray Diffraction Results

X-ray Diffraction Results

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

Microtomy Result

Sample # Mass Before Heating Mass After Heating % Mass Change 1 2.03582g 2.03547 0.01719% 2 1.78192g 1.78138g 0.0303% 3 1.16317g 1.13793g 2.1699% 4 2.74388g 2.72870g 0.55323%

SEM Images Sample 1:

SEM Images Sample 2:

SEM Images Sample 3:

SEM Images Sample 4:

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

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

Acknowledgements Prof. Alex King Indiana 21st Century fund Honeywell

Questions?