Carbon fiber, also known as graphite fiber or carbon graphite, is made from very fine filaments of the element carbon. Carbon fiber has high tensile strength and is very strong for its size. It is also a very light material.
The diameter of each fiber is 5-10 microns. To give you an idea of how small it is, one micron is equal to 0.0001 mm. A spider web filament is between 3 and 8 microns in diameter.
Features and applications
Carbon fiber is twice as hard and five times as strong as steel. Another feature is their high degree of chemical resistance, high temperature resistance and low thermal expansion.
Carbon fiber is an important engineering material in the manufacture of aircraft, high-performance vehicles, sports equipment and musical instruments.
How carbon fiber is made
Carbon fiber is made from organic polymers. These polymers are made up of long strings of molecules linked together by carbon atoms. About 90% of carbon fiber is made using the polyacrylonitrile (PAN) process. The remaining 10% is made using rayon or petroleum bitumen processes.
The gases, liquids and other materials used in the manufacturing process produce certain carbon fiber effects, qualities and grades. The highest grades of carbon fiber with optimal modulus properties are used in demanding applications such as the aerospace industry.
Carbon fiber manufacturers vary in the mix of raw materials they use. They often treat their specific recipes as trade secrets.
manufacturing process
During the manufacturing process, raw materials called precursors are drawn into long fiber bundles. The fibers are then woven into fabric. They can also be combined with other materials, filament-wound or molded into the desired shape and size.
The manufacturing process is as follows:
Rotate. PAN is mixed with other ingredients and spun into fibers, which are then washed and stretched.
Stablize. Chemical changes to stabilize bonds.
Carbonization. The stabilizing fibers are heated to very high temperatures, forming tightly bound carbon crystals.
Treat the surface. The fiber surface is oxidized to improve bonding properties.
sizing. The fibers are coated and wound onto spools. They are then loaded onto spinning machines, which twist the fibers into yarns of different sizes.
Fibers can be formed into composite materials rather than woven into fabrics. To form the composite, heat, pressure or vacuum can be used to bond the fibers to the plastic polymer.
