Properties of carbon fibers- The role of carbon fibers

In order to understand the role that carbon fibers can play, the attributes of carbon fibers must be considered:

1. Available in many grades and forms with wide-ranging properties
2. High modulus, especially pitch based fiber
3. Good strength, especially Pan based fiber
4. Low density, giving good specific properties
5. Good thermal stability in the absence of O₂
6. High thermal conductivity, assisting good fatigue properties
7. Low thermal expansion coefficient
8. Excellent creep resistance
9. Good chemical resistance and does not wick
10. Low electrical resistivity
11. Biocompatibility
12. No significant inhalation problem with filament diameters down to 5 um

The disadvantages are:

1. Relatively high cost, but prices have been falling and more emphasis is now placed on using large tows
2. Low strain to failure with attendant handing problems
3. Compressive strength is lower than tensile strength and larger diameter fiber does not give improved compression properties
4. Poor impact strength of composites
5. Care required during handing carbon fiber, since it is electrically conducting and can cause havoc with electrical systems
6. Oxidizes in air at temperatures above 450C
7. Exhibits anisotropy in the axial and transverse directions

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