Carbon fiber

Carbon fiber is a polymer which is a form of graphite. Graphite is a form of pure carbon. In graphite the carbon atoms are arranged into big sheets of hexagonal aromatic rings. The sheets look like chicken wire.

Carbon fiber is a form of graphite in which these sheets are long and thin. You might think of them as ribbons of graphite. Bunches of these ribbons like to pack together to form fibers, hence the name carbon fiber.

These fibers aren't used by themselves. Instead, they're used to reinforce materials like epoxy resins and other thermosetting materials. We call these reinforced materials composites because they have more than one component.

Carbon fiber reinforced composites are very strong for their weight. They're often stronger than steel, but a whole lot lighter. Because of this, they can be used to replace metals in many uses, from parts for airplanes and the space shuttle to tennis rackets and golf clubs.

Carbon fiber is made from another polymer, called polyacrylonitrile, by a complicated heating process.