Production process
According to “Carbon
Fibers” by Raghavendra R. Hegde, Atul Dahiya, M. G. Kamath (Monika Kannadaguli & Haoming Rong)- updated April 2004 carbon fiber can be made from a
variety of precursor materials and based on what material was used the carbon
fiber is classified as one of the following:
¨
PAN-based
carbon fibers
¨ Pitch-based carbon fibers
¨ Mesophase pitch-based carbon fibers
¨ Isotropic pitch-based carbon fibers
¨ Rayon-based carbon fibers
¨ Gas-phase-grown carbon fibers
The fibers are then heated to varying temperatures to give
the end product the desired properties. Below is a section from the document “Carbon Fibers” by Raghavendra R. Hegde, Atul Dahiya,
M. G. Kamath (Monika Kannadaguli
& Haoming Rong)-
updated April 2004 detailing the manufacturing process of carbon fibers from polyacrylonitrile
(PAN), one of the most common ways of
producing carbon fiber. Although carbon
fibers can be made from many different materials some of the most common are
PAN (as shown below), “cellulosic” fibers
such as cotton and rayon, and coal and petroleum tar pitch.
“Carbon fibers from
POLYACRYLONITRILE (PAN):
There are three successive stages in the conversion of PAN
precursor into high-performance carbon fibers. Oxidative stabilization: The polyacrylonitrile precursor is first stretched and
simultaneously oxidized in a temperature range of 200-300°C.
This treatment converts thermoplastic PAN to a non-plastic cyclic or ladder
compound. Carbonization: After oxidation, the fibers are carbonized at about
1000°C without tension in an inert
atmosphere (normally nitrogen) for a few hours. During this process the
non-carbon elements are removed as volatiles to give carbon fibers with a yield
of about 50% of the mass of the original PAN. 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.
To see a schematic representation of carbon fiber preparation from PAN
fibers (from the source below), click here
To view the
entire excellent document on carbon fiber and for more information on precursor
materials for carbon fibers click the link below
http://www.engr.utk.edu/mse/pages/Textiles/CARBON%20FIBERS.htm