Sorry I could not resist
Definition
Carbon fiber or carbon fibre is also sometimes called graphite fiber. It has the highest compressive strength of all the reinforcing materials (
composite materials), and it has a high strength to weight ratio and low coefficient of thermal expansion. The density of carbon fiber is also much lower than the density of steel.
[1] Carbon fiber is in the form of several thousand long, thin strands of material that is composed of mostly carbon atoms.
[2]
[edit] History of Carbon Fiber
In 1958, Dr. Roger Bacon created the first high performance carbon fibers at the Parma Technical Center outside of Cleveland, OH. Bacon's carbon fibers were mainly graphite whiskers that were sheets of graphite rolled into scrolls; they contained graphite sheets that were continuous over the entire length of the graphite filament. After the development of carbon fiber, Bacon had estimated the cost to make high performance carbon fiber at "$10 million per pound." Bacon's development was a remarkable achievement at the time, and scientists and manufacturers were determined to find a cheaper and efficient way of producing the fibers.
[3]
On the 14th January 1969, Carr Reinforcements wove the first ever Carbon fibre fabric in the world.
[4]
[edit] Structure and properties
A 6 μm diameter carbon filament (running from bottom left to top right) compared to a human hair.
Carbon fibers are the closest to
asbestos in a number of properties.
[5] Each carbon filament thread is a bundle of many thousand carbon filaments. A single such filament is a thin tube with a diameter of 5–8
micrometers and consists almost exclusively of
carbon.
The atomic structure of carbon fiber is similar to that of
graphite, consisting of sheets of carbon
atoms (
graphene sheets) arranged in a regular
hexagonal pattern. The difference lies in the way these sheets interlock. Graphite is a
crystalline material in which the sheets are stacked parallel to one another in regular fashion. The
chemical bonds between the sheets are relatively weak, giving graphite its soft and brittle characteristics. Depending upon the precursor to make the fiber, carbon fiber may be turbostratic or graphitic, or have a hybrid structure with both graphitic and turbostratic parts present. In turbostratic carbon fiber, the sheets of carbon atoms are haphazardly folded, or crumpled, together. Carbon fibers derived from
PAN are turbostratic, whereas carbon fibers derived from
mesophase pitch are graphitic after heat treatment at temperatures exceeding 2200 C. Turbostratic carbon fibers tend to have high
tensile strength, wheresas heat-treated mesophase-pitch-derived carbon fibers have high
Young's modulus and high
thermal conductivity.
[edit] Applications
(For common applications, see
Carbon fiber reinforced polymer or CFRP)
Carbon fiber is most notably used to reinforce
composite materials, particularly the class of materials known as
Carbon fiber or graphite reinforced polymers. Another utilization of Carbon Fiber is its added aesthetic value to various consumer products.
Non-polymer materials can also be used as the matrix for carbon fibres. Due to the formation of metal carbides (i.e., water-soluble AlC) and
corrosion considerations, carbon has seen limited success in
metal matrix composite applications.
Reinforced carbon-carbon (RCC) consists of carbon fibre-reinforced graphite, and is used structurally in high-temperature applications. The fibre also finds use in
filtration of high-temperature gases, as an
electrode with high surface area and impeccable
corrosion resistance, and as an anti-
static component.
[edit] Synthesis
Each
carbon filament is made out of long, thin filaments of carbon sometimes transformed to
graphite. A common method of making carbon filaments is the oxidation and thermal
pyrolysis of
polyacrylonitrile (PAN), a
polymer based on
acrylonitrile used in the creation of synthetic materials. Like all polymers, polyacrylonitrile molecules are long chains, which are aligned in the process of drawing continuous filaments. A common method of manufacture involves heating the PAN to approximately 300 °C in air, which breaks many of the hydrogen bonds, and oxidizes the material. The
oxidized PAN is then placed into a furnace, having an inert atmosphere of a gas such as
argon, and heated to approximately 2000 °C which induces graphitization of the material, changing the molecular bond structure. When heated in the correct conditions, these chains bond side-to-side (ladder polymers), forming narrow
graphene sheets which eventually merge to form a single,
jelly roll-shaped or round filament. The result is usually 93-95% carbon. Lower-quality fibre can be manufactured using
pitch or
rayon as the precursor instead of PAN. The carbon can become further enhanced, as high modulus, or high strength carbon, by heat treatment processes. Carbon heated in the range of 1500-2000 °C (carbonization) exhibits the highest
tensile strength (820,000
psi or 5,650 MPa or 5,650 N/mm²), while carbon fibre heated from 2500 to 3000 °C (graphitizing) exhibits a higher
modulus of elasticity (77,000,000 psi or 531 GPa or 531 kN/mm²
They sure look cool to bad you have to get them so hot before they work, kind of impracticle around town!
Linear Mode
