1. Fabrication Method and Characteristics of Fibers
Aim of 3rd week class
To understand
Fabrication Method and Characteristics of Fibers
Boron fibers
Carbon fibers
Organic fibers
Metallic fibers

2. 3. Boron Fibers
Reaction zone w B
Sic

3. 2BX3+ 3H2----2B + 6HX

4. Boron Hydride Molecular Structure
from

5. Boron Fiber Fabrication by CVD
1.Thermal Decomposition of a Boron Hydride.
Low temperatures, weak
Lack of adherence b/w B and core
Substrate : Glass fiber, low density
2. Reduction of Boron Halide.
2BX3 + 3H2 = 2B + 6HX
X : halogen elements, Cl, Br, I etc
Very high Temp. Strong, Uniform Quality
Substrate: W wire, high density
→ Fig. Schematic Diagram of Reduction of
Boron Halide

7. Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)

8. Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)

9. Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)

11. Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)

12. 4. Carbon Fibers
• carbon fiber is manufactured from organic precursers at high temperature with taking advantage of alignment of a axis through stabilization, carbonization, and graphitization
• Schematic of carbon fiber production
Oxidation
Up to 250℃
Precursor
fiber
Carbonization
250~1500℃
Graphitization
1500~2500℃

13. Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)

14. Carbon/Graphite Fibers
Manufacturing process of carbon/graphite fibers.
1. Polyacrylonitrile (PAN): good properties with relatively low cost
2. Rayon (regenerated cellulose): high and uniform properties but more expensive than Pitch
3. Pitch: lower in cost

15. Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)

16. Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)

17. Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)

18. Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)

19. Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)

20. Comparison of properties of different carbon fibers
Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)

21. Schematic Representation of Carbon Fibers Preparation from PAN
Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)

22. Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)
Carbon Fibers

23. Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)

24. Carbon Fibers
Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)

25. H H H H • Tensile direction- covalent bonding 5. Organic Fibers
• compressive direction- hydrogen , Vander Waals Bonding H H H H

26. Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)

27. Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)

28. Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)

29. Krishan K. Chawla, Composite materials science and engineering, Springer-Verlag, (1998)

30. 5. Organic Fibers
• kevlar - meant mainly for use as rubber reinforcement
for tires
• kevlar 29 - meant for ropes, cables, coated fabrics for
inflatables, architectural…
• kevlar 49 - meant for reinforcement of epoxy,
polyester, and other resins for use in
aerospace, marine……
▶ organic fiber shows anisotropy of mechanical properties.
e.g. Big difference between compressive and tensile strength