Abstract

Elemental carbon, atomic number six in the periodic table, at wt 12.011, occurs naturally throughout the world in either its crystalline (more ordered) or amorphous (less ordered) form. Carbonaceous materials such as soot or charcoal are examples of the amorphous form, whereas graphite and diamond are crystalline. Carbon atoms bond with other carbon atoms as well as with other elements, principally hydrogen, nitrogen, oxygen, and sulfur, to form carbon compounds, which are the subject of organic chemistry. In their many varying manufactured forms, carbon and graphite can exhibit a wide range of electrical, thermal, and chemical properties that are controlled by the selection of raw materials and thermal processing during manufacture. There are two allotropes of carbon: diamond and graphite. A wide variety and range of bulk carbon forms are available within the industry. In general, commercial forms are loosely characterized as carbon or graphite, but they are distinctly different. The term manufactured carbon refers to a bonded granular carbon body whose matrix has been subjected to a temperature typically between 900 and 2400°C. Manufactured graphite refers to a bonded granular carbon body whose matrix has been subjected to a temperature typically in excess of 2400°C. Natural graphite has been known since the Middle Ages, but carbon was first fabricated by H. Davy in his experiments on the electric arc in the early 1800s. The manufacture of artificial graphite came about only at the end of the nineteenth century, preceded by developments in the fabrication of electrodes.

A useful form of graphite is a flexible sheet or foil. Carbon–graphite foam is a prime candidate for thermal protection of new, emerging carbon–carbon aerospace reentry vehicles. Pyrolytic graphite produced in massive shapes is used for missile components, rocket nozzles, and aircraft brakes for advanced high performance aircraft. Glassy, or vitreous, carbon is a black, shiny, dense, brittle material with a vitreous or glass-like appearance. Carbon and graphite paper has outstanding electrical conductivity, corrosion resistance, and moderately high strength.