What is Carbon fiber?
[[File:Kohlenstofffasermatte.jpg|thumb|right|200px|A cloth of woven carbon filaments]] '''Carbon fiber''' (British English: '''carbon fibre''') is a type of fiber that is made of carbon atoms. It is also sometimes called '''graphite fiber'''. It has the highest [[compressive strength]] of all the reinforcing materials ([[Composite material|composites]]), and it has a high [[strength]] to [[weight]] ratio and low [[coefficient]] of [[thermal expansion]]. The [[density]] of carbon fiber is also much lower than the density of [[steel]].<ref>Mr. Jeremy Hierholzer, Assistant Professor of Aviation Technology, Purdue University, 2007.</ref> Carbon fiber is in the form of several thousand long, thin strands of material that is composed of mostly carbon atoms.<ref>{{cite web|url=http://www.madehow.com/Volume-4/Carbon-Fiber.html|title=How carbon fiber is made - material, making, used, processing, parts, components, composition, structure|website=www.madehow.com}}</ref> == Applications == [[File:Cfk heli slw.jpg|120px|thumb|Tail of an RC helicopter, made of [[Carbon fiber reinforced polymer]]]] Carbon fiber is most notably used to reinforce [[composite material]]s, particularly carbon fiber reinforced polymers. [[Reinforced carbon-carbon]] (RCC) is used structurally in high-temperature applications. The fiber is also used to [[filtration|filter]] high-temperature gases. Molding a thin layer of carbon fibers significantly improves fire resistance of polymers or thermoset composites. This works because a dense, compact layer of carbon fibers efficiently reflects heat.<ref>{{cite journal|author=Zhao, Z. and Gou, J. |title=Improved fire retardancy of thermoset composites modified with carbon nanofibers|journal= Sci. Technol. Adv. Mater. |volume=10 |year=2009|issue=1|page=015005 |doi=10.1088/1468-6996/10/1/015005|pmid=27877268|pmc=5109595|bibcode = 2009STAdM..10a5005Z }}</ref> The increasing use of carbon fiber composites is displacing [[aluminum]] from [[aerospace]] applications in favor of other metals.<ref>[http://www.bo