Pyrolytic carbon is a material similar to graphite, but with some covalent bonding between its graphene sheets. Material may refer to one of the following: Material is the matter from which something is or can be made, or also items needed for doing or creating something. ... Graphite (named by Abraham Gottlob Werner in 1789, from the Greek γραφειν: to draw/write, for its use in pencils) is one of the allotropes of carbon. ... Covalently bonded hydrogen and carbon in a molecule of methane. ... Graphene is a single planar sheet of sp² bonded carbon atoms. ...

Generally it is produced by heating a hydrocarbon nearly to its decomposition temperature, and permitting the graphite to crystallise (pyrolysis). One method is to take a synthetic fiber, and heat it in a vacuum. Another method is to place seeds or a plate in the very hot gas to collect the graphite coating. The Decomposition Temperature of a substance is the temperature at which the substance decomposes into smaller substances or into its constituent atoms. ... Quartz crystal A crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions. ... Synthetic fibers are the result of an extensive search by scientists to increase and improve upon the supply of naturally occurring animal and plant fibers that have been used in making cloth. ... For other uses, see vacuum cleaner and Vacuum (musical group). ...

Pyrolytic carbon samples usually have a single cleavage plane, similar to mica, because the graphene sheets crystalize in a planar order (as opposed to graphite, which forms microscopic randomly-oriented zones). Because of this, it is more thermally conductive along the cleavage plane (and less against the plane) than graphite, making it one of the best thermal conductors available. It is also more diamagnetic against the cleavage plane, than along it, exhibiting the greatest diamagnetism of any room temperature solid (by weight). It is possible to levitate reasonably pure and sufficiently ordered samples over rare earth permanent magnets. ImageMetadata File history File links Pyrolytic_graphite. ... Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types: Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes. ... rock with mica Mica sheet mica flakes The mica group of minerals includes several closely related materials having highly perfect basal cleavage. ... In physics, thermal conductivity, λ or k, is the intensive property of a material which relates its ability to conduct heat. ... Diamagnetism is a very weak form of magnetism that is only exhibited in the presence of an external magnetic field. ... Brugmans (in 1778) was the first person to observe that certain materials were repelled by magnetic fields. ... Magnetic levitation is the process by which an object is suspended above another object with no other support but magnetic fields. ... Neodymium magnet on a bracket from a hard drive A neodymium magnet (also called a Neodymium Iron Boron magnet, or less specifically, called a rare-earth magnet) is a powerful magnet made of a combination of neodymium, iron, and boron — Nd2Fe14B. These magnets are very strong in comparison to their...

Applications

It is used unreinforced for missile nosecones, and ablative (uncooled) rocket motors. A missile (CE pronunciation: ; AmE: ) is, in general, a projectile—that is, something thrown or otherwise propelled. ... A nose cone that contained one of the Voyager spacecraft is seen here as it is mounted on top of a Titan III/Centaur launch vehicle. ... Ablation is defined as the removal of material from the surface of an object by vaporization, chipping, or other erosive processes. ... A rocket is a vehicle, missile or aircraft which obtains thrust by the reaction to the ejection of fast moving exhaust from within a rocket engine. ...

In fiber form, it is used to reinforce plastics and metals (see Carbon fiber and Graphite-reinforced plastic). Carbon fiber composite is a strong, light and very expensive material. ... Graphite-reinforced plastic or carbon fiber reinforced plastic (CFRP or CRP), is a strong, light and very expensive composite material or fibre reinforced plastic. ...

Pebble bed nuclear reactors use a coating of pyrolytic carbon as a neutron moderator for the individual pebbles. The pebble bed reactor (PBR) is an advanced nuclear reactor design. ... Core of a nuclear reactor A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate (as opposed to a nuclear explosion, where the chain reaction occurs in a split second). ... In nuclear engineering, a neutron moderator is a medium which reduces the velocity of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction. ...

Biomedical Applications

Because blood clots do not easily form on it, it is often advisable to line a blood-contacting prosthesis with this material in order to reduce the risk of thrombosis. For example, it finds use in artificial hearts and prosthetic heart valves. Blood vessel stents, by contrast, are often lined with a polymer that has heparin as a pendant group, relying on drug action to prevent clotting. This is at least partly because of pyrolytic carbon's brittleness and the large amount of permanent deformation which a stent undergoes during expansion. A United States soldier demonstrates Foosball with two prosthetic limbs In medicine, a prosthesis is an artificial extension that replaces a missing part of the body. ... Thrombosis is the formation of a clot or thrombus inside a blood vessel, obstructing the flow of blood through the circulatory system. ... An artificial heart is a device that is implanted into the body to replace the original biological heart. ... In anatomy, the heart valves are valves in the heart that limits blood flow to a single direction by opening and closing depending on the difference in pressure on each side. ... The arterial system The blood vessels are part of the circulatory system and function to transport blood throughout the body. ... In medicine, a stent is an expandable wire mesh tube that is inserted into a hollow structure of the body to keep it open. ... Heparin - Wikipedia, the free encyclopedia /**/ @import /skins-1. ... A material is brittle if it is subject to fracture when subjected to stress i. ... In physics and materials science, plasticity is a property of a material to undergo a non-reversible change of shape in response to an applied force. ...

Pyrolytic carbon is also in medical use as anatomically correct orthopaedic joint implants. In this application it is currently marketed under the name "pyrocarbon".

External links

Biomedical Applications

• Pyrolytic Carbon for Biomedical Applications