arbon materials

Carbon, as the sixth element in the periodic system, is not only the source material for all organic chemistry and life on Earth, but also utilised in numerous technical areas in the form of carbon materials. A differentiate can be made in this respect between three principle naturally-occurring modifications of carbon, namely hexagonal graphite, cubic diamond and high-symmetrical fullerene. Separate from organic or anorganic compounds containing carbon, anorganic materials mainly consisting of elementary carbon in one of the three modifications are termed carbon materials. These include graphite materials (pure, impregnated or composites with other metals), carbon foams, diamond, active carbon, glassy carbon and carbon nanotubes.

Modifications of carbon differ considerably in numerous material parameters, due to their different bonding ratios. Pure diamond, for example, is an excellent electrical insulator, while graphite materials are more or less good electrical conductors, depending on their composition and pre-treatment. Carbon and graphite foams are very good thermal insulators, even at very high temperatures. Diamond, on the other hand, is used for heat sinking in electronics, due to its very high thermal conductivity. Mechanical characteristics also differ considerably, depending on the type of carbon material involved.

It is therefore no surprise that the variety of applications is also high. The characteristics of graphite materials are variable within very broad limits, so graphite components and parts are used in numerous industrial segments. Applications include carbon brushes in electric motors, current transmission in household and electrical appliances or railway technology, furnace construction, semiconductor technology, medical and analytical engineering, low-wear components in seals, bearings and pumps or core and fusion reactors, just to mention a few. Apart from use as precious stones, diamonds are also used in engineering applications as hard material in cutting and grinding tools or polishing paste, wear-resistant layers or in doped electrically conductive form in high-frequency electronics, synthesis chemistry or waste water treatment. Active carbon is used as an adsorption agent in process gas and waste water treatment, in ventilation and air conditioning and in the area of ABC protection technology. Carbon foams are utilised for high-temperature insulation in furnace construction and heat treatment or as highly porous catalyst carriers. Layers of glassy carbon are used in applications in electro-chemical and chemical process engineering, due to their high resistance to wear and corrosion and good electrical conductivity.