Carbon

MATERIAL OVERVIEW

Characteristics: Relatively soft greasy feel; steel gray to black color with a metallic sheen representative of both metals and nonmetals, thus is generally classified as a metalloid. There are several allotropes of carbon of which the best known are: graphite, diamond, and amorphous carbon. The physical properties of carbon vary widely with the allotropic form. For example, diamond is highly transparent and is the hardest naturally occurring material known, while graphite is opaque and black and soft enough to form a streak on paper (the pencil). Graphite’s softness is a result of the weak bonding between atom layers which provide little resistance to interlayer movement.

Carbon is the 15th most abundant element on Earth, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. It is present in all known life forms, and in the human body carbon is the second most abundant element by mass (about 18.5%) after oxygen. This abundance, together with the unique diversity of organic compounds and unusual polymer-forming ability, make this element the chemical basis of all known life.

Although graphite is considered to have high electrical and thermal conductivity, the electrical resistivity of polycrystalline commercial Graphite is several hundred-fold higher than that of copper.

Graphite is highly inert to chemical attack at normal temperatures. Sufficiently resistant to oxidation and thermal shock for practical utilization at moderate temperatures, however, graphite deteriorates rapidly at high temperatures.

The various grades are available in rod, foil and sheet stock and can be supplied in varying sizes and shapes in accordance with customer’s requirements. Pyrolytic graphite is also available.