Carbon fibre production, morphology, properties and fibre composites

1. Snigdha Chakraborty

2.  Introduction of carbon fibre
 Production of carbon fibre
 Process diagram of production
 Fibre morphology
 Properties- physical, chemical, biological
properties
 Carbon composites
 Uses
 Future scope

4. Raw Materials:
The raw material used to make carbon fiber is called the
precursor.
About 90% of the carbon fibers produced are made from
polyacrylonitrile (PAN).
The remaining 10% are made from rayon or petroleum pitch.
Zoltek, a hungarian company is world’s largest producer
of carbon fibre
(T-B) 50K ribbon, 10K, 6K, 3K Carbon fibre staples

5. CARBON FIBERS FROM POLYACRYLONITRILE (PAN)
There are three successive stages in the conversion of PAN precursor
into high-performance carbon fibers.
1) Oxidation stabilization: The PAN precursor is first stretched and
drawn into long strands of fibers and simultaneously oxidized in a
temperature range of 200-300C which results in stabilization,
meaning the fibre changes from thermoplastic to non plastic.
2) CARBONIZATION: Then it is heated at 1000 C (without oxygen)
in nitrogen for a few hours. Without oxygen the fiber cannot burn.
Instead, the high temperature causes the atoms in the fiber to vibrate
violently until most of the non-carbon atoms are expelled.
3) GRAPHITIZATION: Depending on the type of fiber required, the
fibers are treated at temperatures between 1500-3000C, which
improves the ordering, and orientation of the crystallites in the
direction of the fiber axis.

7. Carbon fiber fabrication from pitch generally consists of the following
four steps:
1) Pitch preparation: It is an adjustment in the molecular weight,
viscosity, and crystal orientation by certain processes.
2) Spinning and drawing: In this stage, pitch is converted into filaments
(by melt spinning process) some alignment in the crystallites to achieve
the directional characteristics.
3) Stabilization: In this step, some kind of thermosetting to maintain the
filament shape during pyrolysis. The stabilization temperature is
between 250 and 400 C.
4) Carbonization: The carbonization temperature is between 1000-
1500C.
CARBON FIBERS FROM PITCH

8. After carbonizing, the fibers have a surface that does not bond well with
the epoxies and other materials. For better bonding properties, their
surface is slightly oxidized.
Oxidation can be achieved by immersing the fibers in various gases such
as air, carbon dioxide, or ozone; or in various liquids such as sodium
hypochlorite or nitric acid.
SIZING
Coating materials are chosen to be compatible with the adhesive used to
form composite materials. Typical coating materials include epoxy,
polyester, nylon, urethane, and others.
 The coated fibers are wound onto cylinders called bobbins. The bobbins
are THEN loaded for spinning.
SURFACE TREATMENT

9. Carbon fibre under
microscope.
It is entirely a mass of
carbon atoms.
The small pores are
created during
carbonization when
the other components
present in PAN are
vaporized.

10. Fibre morphology depends on:
1) Degree of polymerization:
2) Temperature
3) Draw ratio
4) Orientation
5) Crystalline and
amorphous region
And these factors are all interrelated
Here in the picture, we can see the atomic structure of carbon fibre,
By increasing the setting temperature gradually, the orientation of fibres
can be bettered
The crystalline region is increasing in the fibre gradually and amorphous
is decreasing.

11.  1) Tensile Strength- is the maximum stress that a material can withstand
while being stretched or pulled before breaking.
 Carbon fibre has a tensile strength of 4137 MPa compared to normal
steel’s 2693 Mpa. And carbon nanotube’s 11000-13000 Mpa.
 Carbon fiber (Toray T1000G)(the strongest man-made fibres) has 6370
Mpa /fibre .
2) Weight – light weight
Carbon Fiber has High Strength to Weight Ratio (also known as specific
strength) which is 2457 kN.m/kg, glass has 1307 and steel 254.
3) Elasticity- Elasticity is very poor as carbon is a very rigid fibre. Hence
young’s modulus is high. For carbon it’s 180 compared to 0.01-0.1 of
rubber.
 4) Dimensional stability- Very stable dimensionally. Hence used as
composites to make spare parts of missiles, automobiles, aircrafts, etc.

12. 5) Fineness- of carbon fibre is 5-10 micrometer, where as that of carbon
roving is given in the following chart.
6) Moisture regain - It is the ratio between the weight of water with the
oven dry weight of the material express in percentage. For carbon
fibres it is 0 whereas for jute it is 13.75.
7) Thermal property- a measure of how easily heat flows through a
material. Carbon has fairly good thermal conductivity. Carbon Fiber
Reinforced Epoxy has 24, carbon steel is 54. Air is 0.025, Aluminium
has the highest 250.
NO. OF FILAMENTS TEX
3k 3000 200
12K 12000 800
50K 50000 3300

13. 8)Electrical property- Carbon fibre is electrically conductive. Nanotubes of
carbon are used as high conducting materials.
9) Fire retardance- As carbon is chemically inert, it does not get affected
by flame. Can be use to make flame retardant jackets.
10)Affect of oxidation and chemicals- Carbon fiber is Corrosion Resistant
and Chemically Stable.
11) Non Poisonous, Biologically Inert, X-Ray Permeable- These quality
make Carbon fiber useful in Medical applications. Prosthesis use,
implants and tendon repair, x-ray accessories surgical instruments,
are all in development. Although not poisonous, the carbon fibers can
be quite irritating and long term unprotected exposure needs to be
limited.
12) Low Coefficient of Thermal Expansion- This is a measure of how
much a material expands and contracts when the temperature goes
up or down. Units are in Inch / inch degree F.
For carbon fibre it’s <2, for kevlar <3, Aluminium it is 13.

14. 13) Dye ability- carbon fibres are not dyeable.
14) Carbon fibre is brittle- The layers in the fibers are formed by strong
covalent bonds. They readily allow the propagation of cracks. Carbon
fibre does not bend much before failing, the reason being their high
young’s modulus.
CARBON FIBRES COMPOSITES:
Carbon fibres are very expensive. Hence glass or Aramid fibres are used
while weaving a matrix or mesh fabric. These are called carbon
composites.
The composite of glass n carbon is called FIBREGLASS.
Some properties of carbon fibres and their applications are given in the
next chart.

15. 1. Physical strength, toughness, light
weight
Aerospace, road and marine transport,
sporting goods
2. High dimensional stability and low
abrasion
Missiles, aircraft brakes, aerospace antenna
and support structure, large telescopes, optical
benches, waveguides for stable high-frequency
(GHz) precision measurement frames
3. Good vibration damping, strength,
and toughness
Audio equipment, loudspeakers for
equipment, pickup arms, robot arms
4. Electrical conductivity Automobile hoods, novel tooling, casings and
bases for electronic equipments
5. Biological inertness and x-ray
permeability
Medical applications in prostheses, surgery and
x-ray equipment, implants, tendon/ligament
repair
6. Fatigue resistance, self-lubrication,
high damping
Textile machinery, genera engineering
7. Chemical inertness, high corrosion
resistance
Chemical industry; nuclear field; valves, seals,
and pump components in process plants
8. Electromagnetic properties Large generator retaining rings, radiological
equipment

16. Carbon*carbon
twill fabric
Carbon tubes

17. Carbon fiber–reinforced polymer, carbon
fiber–reinforced plastic or carbon fiber–
reinforced thermoplastic (CFRP, CRP,
CFRTP), is an extremely strong and light
fiber-reinforced plastic which contains
carbon fibers.
Carbon-fiber-reinforced polymers are
composite materials. They consists of two
parts: a matrix and a reinforcement.
carbon fiber, which provides the strength. The matrix is usually a polymer
resin, such as epoxy, to bind the reinforcements together.
Carbon nano-tube reinforced polymer (CNRP)
In 2009, Zyvex Technologies introduced carbon nanotube-reinforced
epoxy and carbon prepregs. (CNRP) is several times stronger and
tougher than CFRP and was used in the Lockheed Martin F-35 Lightning
II as a structural material for aircraft

18. Civil
engineering
Automotive engineering
Aerospace
engineering
Carbon fiber
microelectrodes

22. Thank you