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1. CARBON FIBRE
Submitted By
 2019UMT1663
 2019UMT1899
 2019UMT1806
 2019UMT1579
 2019UMT1851
 2019UMT1892

2. CARBON FIBRE
Introduction :
What is Carbon Fiber ?
 A Material Consisting Of Thin, Strong Crystalline Filaments Of Carbon,
Used As A Strengthening Material, Especially In Resins And Ceramics.
 Carbon fiber is composed of carbon atoms bonded together to form a
long chain.
 The fibers are extremely stiff, strong, and light, and are used in many
processes to create excellent building materials for any industry.

3. CARBON FIBER
Structure:
 The atomic structure of the carbon fiber is similar to the graphite one,
which is composed by flat sheets of carbon atoms (Graphene) placed
following a regular hexagonal pattern.
 The difference between each of them is the way that the sheets are
linked.
 The inter-molecular strengths between each sheets are relatively
smaller, (Van Der Waals), giving the graphite its soft and brittle
properties.

4. CARBON FIBER
Structure:
(a) Graphitic layer structure. The layers are shown not in contact for visual ease. (b)
The hexagonal lattice structure of graphite

5. CARBON FIBER
Most of the carbon fiber fabrication processes involve the
following essential steps:
 1. A fiberization procedure to make a precursor fiber. This generally
involves wet-,dry-, or melt-spinning followed by some drawing or
stretching.
 2. A stabilization treatment that prevents the fiber from melting in the
subsequent high-temperature treatments.
 3. A thermal treatment called carbonization that removes most non-
carbon elements.
 4. An optional thermal treatment called graphitization that improves the
properties of carbon fiber obtained in step 3.

6. CARBON FIBERS
Types(Based of precursor fiber materials):
 Ex- PAN Carbon Fibers
 Ex-Cellulose Carbon Fibers
 Ex-Pitch Carbon Fibers

7. EX-PAN CARBON FIBERS:
 Carbon fibers made from PAN are called Ex-PAN carbon fibers.
 Polyacrylonitrile (PAN) is the mostly used precursor for carbon fiber due to its
superior strength and stability, and higher carbon yield.
 About 90% of carbon fibers are made from poly-acrylonitrile(PAN) .

8. Processing of PAN carbon fiber:
 The PAN fibers are stabilized in air (a few hours at 250 C) to prevent melting during the subsequent
higher-temperature treatment.
 The fibers are kept under tension, i.e., they are
prevented from contracting during this oxidation treatment.
 The white PAN fibers become black after oxidation.
 The black fibers obtained after this treatment are
heated slowly in an inert atmosphere to 1,000–1,500 C.
 Slow heating allows the
high degree of order in the fiber to be maintained.
 The rate of temperature increase should be low so as not to destroy the molecular order in the fibers.
 The final optional heat treatment consists of holding the fibers for very short duration at
temperatures up to 3,000 C. This improves the fiber texture
 The carbon fiber yield from PAN is between 50 % by weight.

9. Processing of PAN carbon fiber:

10. EX-PITCH CARBON FIBERS:
PROCESSING STEPS:
 There are four main steps in the production of carbon fiber from pitch
 1) melt spinning
 2) oxidization/pre-carbonization
 3) carbonization and
 4) graphitization.

11. PROCESSING OF PITCH CARBON FIBERS:
1) Melt spinning :
 It is the method of forming fibers through the rapid cooling of a melt; due to
the fast rates of cooling, the mesophase pitch is able to become highly oriented.
Mesophase pitch can be melt spun, but because of its flow characteristics the
process can be difficult.
2) Oxidization/Pre-carbonization:
 is used in order to cross-link the fibers to the point where they cannot be
melted or fused together.
 This step is extremely important because it produces fibers that are stable at the
high temperatures of carbonization and graphitization; otherwise, the fibers would
fail in those steps of the process.

12. PITCH CARBON FIBERS:
3) Carbonization :
 Carbonization is the process removing all non organic elements.
 In the case of carbon fibers, all elements except for carbon are removed. This is
achieved by heating the fibers to high temperatures in an environment without
oxygen.
 This step removes all impurities from the fibers and leaves crystalline carbon
structures.
 These structures are mostly hexagonal in shape and are composed of entirely
carbon.
4) Graphitization :
 is the process of treating the fibers at high temperatures in order to improve
the alignment and orientation of the crystalline regions along the fiber direction.

13. Ex- Cellulose CARBON FIBERS AND
PROCESSING :
 Cellulose is a natural polymer that is frequently found in a fibrous form. In fact,
cotton fiber, which is cellulosic, was one of the first to be carbonized.
 The cellulose is extracted from wood pulp, and continuous filament tows are produced
by wet spinning.
 Rayon is a thermosetting polymer.
 The process used for the conversion of
rayon into carbon fiber involves the same stages: fiberization, stabilization in a
reactive atmosphere (air or oxygen, <400 C), carbonization (<1,500 C), and
graphitization (>2,500 C).

14. Ex- Cellulose CARBON FIBERS:
 Various reactions occur during the first stage, causing extensive decomposition
and evolution of H2O, CO, CO2 , and tar.
 The stabilization is carried out in a reactive atmosphere to inhibit tar formation
and improve yield.
 The carbonization treatment involves heating to about 1,000 C in nitrogen.
 Graphitization is carried out at 2,800 C under stress.
 The carbon fiber yield from rayon is between 15 and 30 % by weight

15. CARBON FIBER
Properties:
 High tensile strength.
 Low thermal expansion.
 Electrically and thermally conductors.
 Light weight and low density.
 Density : 1.95 gm/cc
 Melting point : 3652 – 3697 C
 Boiling point : 4200 C

16. CARBON FIBER
Properties:
 Ability to protest friction: Good
 Good creep resistance
 Colour: Black
 Lustre : Like silky
 Ability to protest heat : Good
 Protection against flame : Excellent

17. Disadvantages
 High cost of production
 Requires molds that are resistant to high temperature
 Limitation to design phase
 Its electric conductivity is less than metals
 Effect of sunlight
 Repair of carbon fibers composites

18. APPLICATION OF CARBON FIBERS:
 Civil Engineering
 Sports equipment's
 Aerospace and Aircraft industry
 Acoustics
 Portable power
 Building and construction materials
 Fiber reinforced plastics