TheInfoList

Carbon fiber reinforced polymer (
American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of variety (linguistics), varieties of the English language native to the United States. Currently, American English is the m ...
), Carbon fibre reinforced polymer (
Commonwealth English The use of the English language English is a of the , originally spoken by the inhabitants of . It is named after the , one of the ancient that migrated from , a peninsula on the (not to be confused with ), to the area of later nam ...
), or carbon fiber reinforced plastic, or carbon fiber reinforced thermoplastic (CFRP, CRP, CFRTP, also known as carbon fiber, carbon composite, or just carbon), is an extremely strong and light
fiber-reinforced plastic Fibre-reinforced plastic (FRP) (also called fiber-reinforced polymer, or fiber-reinforced plastic) is a composite material made of a polymer matrix reinforced with fibres. The fibres are usually glass fibre, glass (in fibreglass), Carbon fibers, c ...
which contains
carbon fibers Carbon fibers American and British English spelling differences, or carbon fibres (alternatively CF, graphite fiber or graphite fibre) are fibers about in diameter and composed mostly of carbon atoms. Carbon fibers have several advantages i ...
. CFRPs can be expensive to produce, but are commonly used wherever high
strength-to-weight ratio The specific strength is a material's strength (force per unit area at failure) divided by its density The density (more precisely, the volumetric mass density; also known as specific mass), of a substance is its mass per unit volume. The sym ...
and
stiffness Stiffness is the extent to which an object resists Deformation (mechanics), deformation in response to an applied force. The complementary concept is flexibility or pliability: the more flexible an object is, the less stiff it is. Calculations ...
(rigidity) are required, such as aerospace, superstructures of ships, automotive, civil engineering,
sports equipment Sporting equipment, also called sporting goods, are the tools, materials, apparel, and gear used to compete in a sport and varies depending on the sport. The equipment ranges from balls, nets, and protective gear Personal protective equipme ...
, and an increasing number of consumer and technical applications. The binding
polymer A polymer (; Greek ''poly- Poly, from the Greek :wikt:πολύς, πολύς meaning "many" or "much", may refer to: Businesses * China Poly Group Corporation, a Chinese business group, and its subsidiaries: ** Poly Property, a Hong Kong inc ...

is often a
thermoset A thermosetting polymer, resin, or plastic, often called a thermoset, is a polymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecule File:Pentacene on Ni(111) STM.jpg, ...
resin such as
epoxy Epoxy is the family of basic components or cured A cure is a completely effective treatment for a disease. Cure, or similar, may also refer to: Places * Cure (river), a river in France * Cures, Sabinum, an ancient Italian town * Cures, Sa ...

, but other thermoset or
thermoplastic A thermoplastic, or thermosoft plastic, is a plastic polymer A polymer (; Greek ''wikt:poly-, poly-'', "many" + ''wikt:-mer, -mer'', "part") is a Chemical substance, substance or material consisting of very large molecules, or macromolecules, ...
polymers, such as
polyester Polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include natural ...
,
vinyl ester image:Vinyl_acetate.png, left, 144px, Vinyl acetate is a commercially important monomer that is classified as a vinyl ester (i.e. an ester of vinyl alcohol). Vinyl ester refers to esters formerly derived from vinyl alcohol. Commercially important ...
, or
nylon Nylon is a generic designation for a family of s composed of s ( linked by links).The polyamides may be or . Nylon is a -like , generally made from , that can be melt-processed into fibers, , or shapes. Nylon polymers can be mixed with a w ...

, are sometimes used. The properties of the final CFRP product can be affected by the type of additives introduced to the binding matrix (resin). The most common additive is
silica Silicon dioxide, also known as silica, is an oxide An oxide () is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any su ...

, but other additives such as rubber and
carbon nanotube image of a single-walled carbon nanotube. Carbon nanotubes (CNTs) are tubes made of carbon with diameters typically measured in nanometers The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI ...

s can be used. Carbon fiber is sometimes referred to as ''graphite-reinforced polymer'' or ''graphite fiber-reinforced polymer'' (''GFRP'' is less common, as it clashes with glass-(fiber)-reinforced polymer).

# Properties

CFRP are
composite material A composite material (also called a composition material or shortened to composite, which is the common name) is a material Material is a substance Substance may refer to: * Substance (Jainism), a term in Jain ontology to denote the base or o ...

s. In this case the composite consists of two parts: a matrix and a reinforcement. In CFRP the reinforcement is carbon fiber, which provides its strength. The matrix is usually a polymer resin, such as epoxy, to bind the reinforcements together. Because CFRP consists of two distinct elements, the material properties depend on these two elements. Reinforcement gives CFRP its strength and rigidity, measured by stress and
elastic modulus An elastic modulus (also known as modulus of elasticity) is a quantity that measures an object or substance's resistance to being deformed elastically (i.e., non-permanently) when a stress is applied to it. The elastic modulus of an object is defi ...
respectively. Unlike
isotropic Isotropy is uniformity in all orientations; it is derived from the Greek ''isos'' (ἴσος, "equal") and ''tropos'' (τρόπος, "way"). Precise definitions depend on the subject area. Exceptions, or inequalities, are frequently indicated by ...
materials like steel and aluminum, CFRP has directional strength properties. The properties of CFRP depend on the layouts of the carbon fiber and the proportion of the carbon fibers relative to the polymer. The two different equations governing the net elastic modulus of composite materials using the properties of the carbon fibers and the polymer matrix can also be applied to carbon fiber reinforced plastics. The following equation, :$E_c = V_mE_m + V_fE_f$ is valid for composite materials with the fibers oriented in the direction of the applied load. $E_c$ is the total composite modulus, $V_m$ and $V_f$ are the volume fractions of the matrix and fiber respectively in the composite, and $E_m$ and $E_f$ are the elastic moduli of the matrix and fibers respectively. The other extreme case of the elastic modulus of the composite with the fibers oriented transverse to the applied load can be found using the following equation: :$E_c = \left\left( \frac + \frac \right\right)^$ The fracture toughness of carbon fiber reinforced plastics is governed by the following mechanisms: 1) debonding between the carbon fiber and polymer matrix, 2) fiber pull-out, and 3) delamination between the CFRP sheets. Typical epoxy-based CFRPs exhibit virtually no plasticity, with less than 0.5% strain to failure. Although CFRPs with epoxy have high strength and elastic modulus, the brittle fracture mechanics present unique challenges to engineers in failure detection since failure occurs catastrophically. As such, recent efforts to toughen CFRPs include modifying the existing epoxy material and finding alternative polymer matrix. One such material with high promise is
PEEK Polyether ether ketone (PEEK) is a colourless organic thermoplastic A thermoplastic, or thermosoftening plastic, is a plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Most t ...
, which exhibits an order of magnitude greater toughness with similar elastic modulus and tensile strength. However, PEEK is much more difficult to process and more expensive. Despite its high initial strength-to-weight ratio, a design limitation of CFRP is its lack of a definable
fatigue limit 350px, Representative curves of applied stress vs number of cycles for steel (showing an endurance limit) and aluminium (showing no such limit). The fatigue limit or endurance limit is the stress level below which an infinite number of loading cyc ...
. This means, theoretically, that stress cycle failure cannot be ruled out. While steel and many other structural metals and alloys do have estimable fatigue or endurance limits, the complex failure modes of composites mean that the fatigue failure properties of CFRP are difficult to predict and design against. As a result, when using CFRP for critical cyclic-loading applications, engineers may need to design in considerable strength safety margins to provide suitable component reliability over its service life. Environmental effects such as temperature and humidity can have profound effects on the polymer-based composites, including most CFRPs. While CFRPs demonstrate excellent corrosion resistance, the effect of moisture at wide ranges of temperatures can lead to degradation of the mechanical properties of CFRPs, particularly at the matrix-fiber interface. While the carbon fibers themselves are not affected by the moisture diffusing into the material, the moisture plasticizes the polymer matrix. This led to significant changes in properties that are dominantly influenced by the matrix in CFRPs such as compressive, interlaminar shear, and impact properties. The epoxy matrix used for engine fan blades is designed to be impervious against jet fuel, lubrication, and rain water, and external paint on the composites parts is applied to minimize damage from ultraviolet light. The carbon fibers can cause
galvanic corrosion Galvanic corrosion (also called bimetallic corrosion or dissimilar metal corrosion) is an electrochemical Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential, as a measurable and quant ...
when CRP parts are attached to aluminum. Carbon Fiber Reinforced Plastics are very hard to machine, and causes significant tool wear. The tool wear in CFRP machining is dependent on the fiber orientation and machining condition of the cutting process. In order to reduce tool wear various types of coated tools are used in machining CFRP and CFRP-metal stack.

# Manufacture

The primary element of CFRP is a ; this is produced from a precursor
polymer A polymer (; Greek ''poly- Poly, from the Greek :wikt:πολύς, πολύς meaning "many" or "much", may refer to: Businesses * China Poly Group Corporation, a Chinese business group, and its subsidiaries: ** Poly Property, a Hong Kong inc ...

such as
polyacrylonitrile Polyacrylonitrile (PAN), also known as polyvinyl cyanide and Creslan 61, is a synthetic, semicrystalline organic polymer A polymer (; Greek ''wikt:poly-, poly-'', "many" + ''wikt:-mer, -mer'', "part") is a Chemical substance, substance or ma ...

(PAN),
rayon Rayon is a synthetic fiber Synthetic fiber or synthetic fibre (in British English British English (BrE) is the standard dialect A standard language (also standard variety, standard dialect, and standard) is a language variety that ...

, or petroleum
pitch Pitch may refer to: Acoustic frequency * Pitch (music), the perceived frequency of sound including "definite pitch" and "indefinite pitch" ** Absolute pitch or "perfect pitch" ** Pitch class, a set of all pitches that are a whole number of octaves ...
. For synthetic polymers such as PAN or rayon, the precursor is first
spun ''Spun'' is a 2003 American black comedy Black comedy, also known as black humor, dark humor, dark comedy, morbid humor, or gallows humor, is a style of comedy Comedy (from the el, wikt:κωμῳδία, κωμῳδία, ''kōmōdía'') i ...
into filament yarns, using chemical and mechanical processes to initially align the polymer chains in a way to enhance the final physical properties of the completed carbon fiber. Precursor compositions and mechanical processes used during spinning filament yarns may vary among manufacturers. After drawing or spinning, the polymer filament yarns are then heated to drive off non-carbon atoms (
carbonization Carbonization is the conversion of organic matters like plants and dead animal remains into carbon Carbon (from la, carbo "coal") is a chemical element with the Symbol (chemistry), symbol C and atomic number 6. It is nonmetallic and tetraval ...
), producing the final carbon fiber. The carbon fibers filament yarns may be further treated to improve handling qualities, then wound on to
bobbin A bobbin is a spindle or cylinder, with or without s, on which , , thread or is wound. Bobbins are typically found in s, s, and within equipment. In non-electrical applications the bobbin is used for and tidy storage without tangles. In ...
s. From these fibers, a unidirectional sheet is created. These sheets are layered onto each other in a quasi-isotropic layup, e.g. 0°, +60°, or −60° relative to each other. From the elementary fiber, a bidirectional woven sheet can be created, i.e. a
twill Twill is a type of with a pattern of diagonal parallel ribs. It is one of three fundamental types of along with and . It is made by passing the thread over one or more threads then under two or more warp threads and so on, with a "step, ...

with a 2/2 weave. The process by which most CFRPs are made varies, depending on the piece being created, the finish (outside gloss) required, and how many of the piece will be produced. In addition, the choice of matrix can have a profound effect on the properties of the finished composite. Many CFRP parts are created with a single layer of carbon fabric that is backed with fiberglass. A tool called a chopper gun is used to quickly create these composite parts. Once a thin shell is created out of carbon fiber, the chopper gun cuts rolls of fiberglass into short lengths and sprays resin at the same time, so that the fiberglass and resin are mixed on the spot. The resin is either external mix, wherein the hardener and resin are sprayed separately, or internal mixed, which requires cleaning after every use. Manufacturing methods may include the following:

## Molding

One method of producing CFRP parts is by layering sheets of carbon fiber cloth into a
mold A mold () or mould () is a fungus A fungus (plural The plural (sometimes abbreviated An abbreviation (from Latin ''brevis'', meaning ''short'') is a shortened form of a word or phrase, by any method. It may consist of a group of ...
in the shape of the final product. The alignment and weave of the cloth fibers is chosen to optimize the strength and stiffness properties of the resulting material. The mold is then filled with
epoxy Epoxy is the family of basic components or cured A cure is a completely effective treatment for a disease. Cure, or similar, may also refer to: Places * Cure (river), a river in France * Cures, Sabinum, an ancient Italian town * Cures, Sa ...

and is heated or air-cured. The resulting part is very corrosion-resistant, stiff, and strong for its weight. Parts used in less critical areas are manufactured by draping cloth over a mold, with epoxy either preimpregnated into the fibers (also known as ''
pre-pregPre-preg is a composite material made from "pre-impregnated" fibers and a ''partially cured'' polymer matrix, such as epoxy or phenolic resin, or even thermoplastic A thermoplastic, or thermosoftening plastic, is a plastic polymer material that b ...
'') or "painted" over it. High-performance parts using single molds are often vacuum-bagged and/or
autoclave An autoclave is a machine used to carry out industrial and scientific processes requiring elevated temperature and pressure in relation to ambient pressure/Ambient temperature, temperature. Autoclaves are used in medical applications to perform ...
-cured, because even small air bubbles in the material will reduce strength. An alternative to the autoclave method is to use internal pressure via inflatable air bladders or inside the non-cured laid-up carbon fiber.

## Vacuum bagging

For simple pieces of which relatively few copies are needed (1–2 per day), a vacuum bag can be used. A fiberglass, carbon fiber, or aluminum mold is polished and waxed, and has a
release agent A release agent (also mold release agent, release coating, or mold release coating) is a chemical used to prevent other materials from bonding to surfaces. It can provide a solution in processes involving mold release, die-cast release, plastic ...
applied before the fabric and resin are applied, and the vacuum is pulled and set aside to allow the piece to cure (harden). There are three ways to apply the resin to the fabric in a vacuum mold. The first method is manual and called a wet layup, where the two-part resin is mixed and applied before being laid in the mold and placed in the bag. The other one is done by infusion, where the dry fabric and mold are placed inside the bag while the vacuum pulls the resin through a small tube into the bag, then through a tube with holes or something similar to evenly spread the resin throughout the fabric. Wire loom works perfectly for a tube that requires holes inside the bag. Both of these methods of applying resin require hand work to spread the resin evenly for a glossy finish with very small pin-holes. A third method of constructing composite materials is known as a dry layup. Here, the carbon fiber material is already impregnated with resin (pre-preg) and is applied to the mold in a similar fashion to adhesive film. The assembly is then placed in a vacuum to cure. The dry layup method has the least amount of resin waste and can achieve lighter constructions than wet layup. Also, because larger amounts of resin are more difficult to bleed out with wet layup methods, pre-preg parts generally have fewer pinholes. Pinhole elimination with minimal resin amounts generally require the use of
autoclave An autoclave is a machine used to carry out industrial and scientific processes requiring elevated temperature and pressure in relation to ambient pressure/Ambient temperature, temperature. Autoclaves are used in medical applications to perform ...
pressures to purge the residual gases out.

## Compression molding

A quicker method uses a . This is a two-piece (male and female) mold usually made out of aluminum or steel that is pressed together with the fabric and resin between the two. The benefit is the speed of the entire process. Some car manufacturers, such as BMW, claimed to be able to cycle a new part every 80 seconds. However, this technique has a very high initial cost since the molds require CNC machining of very high precision.

## Filament winding

For difficult or convoluted shapes, a filament winder can be used to make CFRP parts by winding filaments around a mandrel or a core.

# Applications

Applications for CFRP include the following:

## Aerospace engineering

The
Airbus A350 XWB The Airbus A350 is a long-range, wide-body jet airliner developed by Airbus Airbus SE (; ; ; ) is a European multinational aerospace corporation. Airbus designs, manufactures and sells civil and military aerospace Aerospace is a ...

is built of 52% CFRP including wing spars and fuselage components, overtaking the
Boeing 787 Dreamliner The Boeing 787 Dreamliner is an American wide-body jet airliner manufactured by Boeing Commercial Airplanes Boeing Commercial Airplanes (BCA) is a division (business), division of Boeing, the Boeing Company. It Aircraft design process, de ...

, for the aircraft with the highest weight ratio for CFRP, which is 50%. This was one of the first commercial aircraft to have wing spars made from composites. The
Airbus A380 The Airbus A380 is a wide-body aircraft A wide-body aircraft, also known as a twin-aisle aircraft, is an airliner An airliner is a type of aircraft for transporting passengers and air cargo. Such aircraft are most often operated b ...

was one of the first commercial airliners to have a central wing-box made of CFRP; it is the first to have a smoothly contoured wing cross-section instead of the wings being partitioned span-wise into sections. This flowing, continuous cross section optimises aerodynamic efficiency. Moreover, the trailing edge, along with the rear bulkhead,
empennage The empennage ( or ), also known as the tail or tail assembly, is a structure at the rear of an aircraft that provides stability during flight, in a way similar to the feathers on an arrow s and nock. An arrow is a fin-stabilized projectile la ...
, and un-pressurised fuselage are made of CFRP. However, many delays have pushed order delivery dates back because of problems with the manufacture of these parts. Many aircraft that use CFRP have experienced delays with delivery dates due to the relatively new processes used to make CFRP components, whereas metallic structures have been studied and used on airframes for years, and the processes are relatively well understood. A recurrent problem is the monitoring of structural ageing, for which new methods are constantly investigated, due to the unusual multi-material and anisotropic nature of CFRP. In 1968 a ''Hyfil'' carbon-fiber fan assembly was in service on the
Rolls-Royce Conway Rolls-Royce (always hyphenated) may refer to: * Rolls-Royce Limited Rolls-Royce was a British luxury car and later an aero-engine manufacturing business established in 1904 in Manchester Manchester () is the most-populous city and metr ...

s of the
Vickers VC10 The Vickers VC10 is a mid-sized, narrow-body A narrow-body aircraft or single-aisle aircraft is an airliner arranged along a single aisle, permitting up to 6-abreast seating in a cabin below of width. In contrast, a wide-body aircraft ...

s operated by BOAC. Specialist aircraft designers and manufacturers
Scaled Composites Scaled Composites (often called simply Scaled) is an American aerospace company founded by Burt Rutan and currently owned by Northrop Grumman. It is located at the Mojave Air and Space Port in Mojave, California, United States. Founded to devel ...
have made extensive use of CFRP throughout their design range, including the first private manned spacecraft Spaceship One. CFRP is widely used in micro air vehicles (MAVs) because of its high strength to weight ratio.

## Automotive engineering

CFRPs are extensively used in high-end automobile racing. The high cost of carbon fiber is mitigated by the material's unsurpassed strength-to-weight ratio, and low weight is essential for high-performance automobile racing. Race-car manufacturers have also developed methods to give carbon fiber pieces strength in a certain direction, making it strong in a load-bearing direction, but weak in directions where little or no load would be placed on the member. Conversely, manufacturers developed omnidirectional carbon fiber weaves that apply strength in all directions. This type of carbon fiber assembly is most widely used in the "safety cell"
monocoque Monocoque (), also called structural skin, is a structural system in which loads are supported by an object's external skin, in a manner similar to an egg shell. The word ''monocoque'' is a French language, French term for "single shell". First u ...
chassis assembly of high-performance race-cars. The first carbon fiber monocoque chassis was introduced in
Formula One Formula One (also known as Formula 1 or F1) is the highest class of international racing for single-seater An open-wheel car (formula car, or often single-seater car in British English) is a car with the wheels outside the car's main body ...
by
McLaren McLaren Racing Limited is a British motor racing Motorsport, motorsports or motor sport is a global term used to encompass the group of competitive sporting events which primarily involve the use of motorised vehicles, whether for racin ...

in the 1981 season. It was designed by
John Barnard John Barnard (born 4 May 1946, Wembley Wembley (/ˈwɛmbli/) is a largely suburban town in north-west London London is the capital city, capital and List of urban areas in the United Kingdom, largest city of England and the United Kin ...

and was widely copied in the following seasons by other F1 teams due to the extra rigidity provided to the chassis of the cars. Many
supercar A supercar – also called exotic car – is a loosely defined description of street-legal, high-performance luxury sports car. Since the 2000s or 2010s, the term hypercar has come into use for the highest performing supercars. Supercars comm ...
s over the past few decades have incorporated CFRP extensively in their manufacture, using it for their monocoque chassis as well as other components. As far back as 1971, the offered optional lightweight carbon fiber wheels. Use of the material has been more readily adopted by low-volume manufacturers who used it primarily for creating body-panels for some of their high-end cars due to its increased strength and decreased weight compared with the glass-reinforced polymer they used for the majority of their products.

## Civil engineering

CFRP has become a notable material in
structural engineering Structural engineering is a sub-discipline of in which s are trained to design the 'bones and muscles' that create the form and shape of man-made structures. also must understand and calculate the , strength, and earthquake-susceptibility of ...
applications. Studied in an academic context as to its potential benefits in construction, it has also proved itself cost-effective in a number of field applications strengthening concrete, masonry, steel, cast iron, and timber structures. Its use in industry can be either for retrofitting to strengthen an existing structure or as an alternative reinforcing (or pre-stressing) material instead of steel from the outset of a project.
Retrofitting Retrofitting is the addition of new technology or features to older systems, for example: * power plantPower Station or The Power Station may refer to: * Power station, a facility for the generation of electricity Music * The Power Station (ban ...
has become the increasingly dominant use of the material in civil engineering, and applications include increasing the load capacity of old structures (such as
bridge A bridge is a Nonbuilding structure, structure built to Span (engineering), span a physical obstacle, such as a body of water, valley, or road, without closing the way underneath. It is constructed for the purpose of providing passage over the ...

s) that were designed to tolerate far lower service loads than they are experiencing today, seismic retrofitting, and repair of damaged structures. Retrofitting is popular in many instances as the cost of replacing the deficient structure can greatly exceed the cost of strengthening using CFRP. Applied to reinforced concrete structures for flexure, CFRP typically has a large impact on strength (doubling or more the strength of the section is not uncommon), but only a moderate increase in stiffness (perhaps a 10% increase). This is because the material used in this application is typically very strong (e.g., 3000 MPa ultimate
tensile strength In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies matter, its Motion (physics), motion and behavior through Spa ...
, more than 10 times mild steel) but not particularly stiff (150 to 250 GPa, a little less than steel, is typical). As a consequence, only small cross-sectional areas of the material are used. Small areas of very high strength but moderate stiffness material will significantly increase strength, but not stiffness. CFRP can also be applied to enhance shear strength of reinforced concrete by wrapping fabrics or fibers around the section to be strengthened. Wrapping around sections (such as bridge or building columns) can also enhance the ductility of the section, greatly increasing the resistance to collapse under earthquake loading. Such 'seismic retrofit' is the major application in earthquake-prone areas, since it is much more economic than alternative methods. If a column is circular (or nearly so) an increase in axial capacity is also achieved by wrapping. In this application, the confinement of the CFRP wrap enhances the compressive strength of the concrete. However, although large increases are achieved in the ultimate collapse load, the concrete will crack at only slightly enhanced load, meaning that this application is only occasionally used. Specialist ultra-high modulus CFRP (with tensile modulus of 420 GPa or more) is one of the few practical methods of strengthening cast-iron beams. In typical use, it is bonded to the tensile flange of the section, both increasing the stiffness of the section and lowering the
neutral axis The neutral axis is an axis in the cross section of a beam Beam may refer to: Streams of particles or energy *Light beam, or beam of light, a directional projection of light energy **Laser beam *Particle beam, a stream of charged or neutral p ...
, thus greatly reducing the maximum tensile stress in the cast iron. In the United States, pre-stressed concrete cylinder pipes (PCCP) account for a vast majority of water transmission mains. Due to their large diameters, failures of PCCP are usually catastrophic and affect large populations. Approximately of PCCP have been installed between 1940 and 2006. Corrosion in the form of hydrogen embrittlement has been blamed for the gradual deterioration of the pre-stressing wires in many PCCP lines. Over the past decade, CFRPs have been utilized to internally line PCCP, resulting in a fully structural strengthening system. Inside a PCCP line, the CFRP liner acts as a barrier that controls the level of strain experienced by the steel cylinder in the host pipe. The composite liner enables the steel cylinder to perform within its elastic range, to ensure the pipeline's long-term performance is maintained. CFRP liner designs are based on strain compatibility between the liner and host pipe. CFRP is a more costly material than its counterparts in the construction industry, glass fiber-reinforced polymer (GFRP) and aramid fiber-reinforced polymer (AFRP), though CFRP is, in general, regarded as having superior properties. Much research continues to be done on using CFRP both for retrofitting and as an alternative to steel as a reinforcing or pre-stressing material. Cost remains an issue and long-term durability questions still remain. Some are concerned about the brittle nature of CFRP, in contrast to the ductility of steel. Though design codes have been drawn up by institutions such as the American Concrete Institute, there remains some hesitation among the engineering community about implementing these alternative materials. In part, this is due to a lack of standardization and the proprietary nature of the fiber and resin combinations on the market.

## Carbon-fiber microelectrodes

Carbon fibers are used for fabrication of carbon-fiber
microelectrode A microelectrode is an electrode used in electrophysiology either for recording Action potential, neural signals or for the electrical stimulation of nervous tissue (they were first developed by Ida Henrietta Hyde, Ida Hyde in 1921). Pulled glas ...
s. In this application typically a single carbon fiber with diameter of 5–7 μm is sealed in a glass capillary. At the tip the capillary is either sealed with epoxy and polished to make carbon-fiber disk microelectrode or the fiber is cut to a length of 75–150 μm to make carbon-fiber cylinder electrode. Carbon-fiber microelectrodes are used either in amperometry or
fast-scan cyclic voltammetry Fast-scan cyclic voltammetry (FSCV) is cyclic voltammetry Cyclic voltammetry (CV) is a type of potentiodynamic electrochemical measurement. In a cyclic voltammetry experiment, the working electrode potential is ramped linearly versus time. Unlike ...
for detection of biochemical signaling.

## Sports goods

CFRP is now widely used in sports equipment such as in squash, tennis, and badminton racquets,
sport kite A sport kite, also commonly known as a stunt kite, is a kite that can be maneuvered in the air. A related kite, also controllable and used for recreation, but capable of generating a significant amount of pull and used for providing movement, is ...
spars, high-quality arrow shafts, hockey sticks, fishing rods,
surfboard A surfboard is a narrow plank used in surfing. Surfboards are relatively light, but are strong enough to support an individual standing on them while riding an ocean wave. They were invented in ancient Hawaii, where they were known as ''papa he'e ...

s, high end swim fins, and rowing
shells Shell may refer to: Architecture and design * Shell (structure), a thin structure **Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses **Thin-shell structure, **Oil company Science Biology * Seashell ...
. Amputee athletes such as
Jonnie Peacock Jonathan Peacock, Order of the British Empire, MBE (born 28 May 1993) is an English sprint (running), sprint runner... An amputee, Peacock won gold at the 2012 Summer Paralympics and 2016 Summer Paralympics, representing Great Britain at the Par ...

use carbon fiber blades for running. It is used as a shank plate in some
basketball Basketball is a team sport in which two teams, most commonly of five players each, opposing one another on a rectangular court A court is any person or institution, often as a government institution, with the authority to Adjudication, ...

sneakers to keep the foot stable, usually running the length of the shoe just above the sole and left exposed in some areas, usually in the arch. Controversially, in 2006, cricket bats with a thin carbon-fiber layer on the back were introduced and used in competitive matches by high-profile players including
Ricky Ponting Ricky Thomas Ponting (born 19 December 1974) is an Australian cricket coach, commentator, and former cricketer. Ponting was captain of the Australia national cricket team, Australian national team during its "golden era", between 2004 and 2011 ...

and
Michael Hussey Michael Edward Killeen Hussey (born 27 May 1975) is an Australian cricket coach, commentator and former international cricket Cricket is a Bat-and-ball games, bat-and-ball game played between two teams of eleven players on a cricket field, ...
. The carbon fiber was claimed to merely increase the durability of the bats, but it was banned from all first-class matches by the
ICC ICC may refer to: Buildings * International Commerce Centre, a skyscraper in Hong Kong * International Commercial Center, a skyscraper in Ulaanbaatar, Mongolia * International Convention Centre (disambiguation), any of several convention centers * ...
in 2007. A CFRP
bicycle frame A bicycle frame is the main component of a bicycle Classic bell of a bicycle A bicycle, also called a bike or cycle, is a human-powered or motor-powered, pedal-driven, single-track vehicle A single-track vehicle is a vehicle that leaves ...
weighs less than one of
steel Steel is an alloy An alloy is an admixture of metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appe ...

,
aluminum Aluminium (aluminum in American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the United States The United States of America (USA), commonly known as the Uni ...

, or
titanium Titanium is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical ele ...

having the same strength. The type and orientation of the carbon-fiber weave can be designed to maximize stiffness in required directions. Frames can be tuned to address different riding styles: sprint events require stiffer frames while endurance events may require more flexible frames for rider comfort over longer periods. The variety of shapes it can be built into has further increased stiffness and also allowed
aerodynamic study at Wallops Flight Facility, Wallops Island in 1990. A vortex is created by passage of an aircraft wing, revealed by smoke. Vortices are one of the many phenomena associated with the study of aerodynamics. Aerodynamics, from Greek language, ...
tube sections. CFRP
forks In cutlery or kitchenware, a fork (from la, furca 'pitchfork') is a utensil, now usually made of metal, whose long handle terminates in a head that branches into several narrow and often slightly curved tine (structural), tines with which one ...
including suspension fork crowns and steerers, handlebars,
seatpost (red). bike. A bicycle seatpost, seatpin, saddlepole, saddle pillar, or saddle pin is a tube that extends upwards from the bicycle frame to the saddle The saddle is a supportive structure for a professional other load, fastened to an ani ...
s, and crank arms are becoming more common on medium as well as higher-priced bicycles. CFRP remain expensive but their stability compared to aluminium reduces the need to re-true a wheel and the reduced mass reduces the
moment of inertia The moment of inertia, otherwise known as the mass moment of inertia, angular mass, second moment of mass, or most accurately, rotational inertia, of a rigid body In physics Physics is the natural science that studies matter, its ...

of the wheel. CFRP spokes are rare and most carbon wheelsets retain traditional stainless steel spokes. CFRP also appears increasingly in other components such as derailleur parts, brake and shifter levers and bodies, cassette sprocket carriers, suspension linkages, disc brake rotors, pedals, shoe soles, and saddle rails. Although strong and light, impact, over-torquing, or improper installation of CFRP components has resulted in cracking and failures, which may be difficult or impossible to repair.

## Other applications

The fire resistance of polymers and thermo-set composites is significantly improved if a thin layer of carbon fibers is moulded near the surface because a dense, compact layer of carbon fibers efficiently reflects heat. CFRP is being used in an increasing number of high-end products that require stiffness and low weight, these include: *Musical instruments, including violin bows; guitar picks, necks (carbon fiber rods), and pick-guards; drum shells; bagpipe chanters; and entire musical instruments such as
Luis and Clark Luis and Clark, or L&C, is a small, family run company that sells carbon fiber Carbon fiber reinforced polymer (American English), Carbon fibre reinforced polymer (English in the Commonwealth of Nations, Commonwealth English), or carbon fiber ...
's carbon fiber cellos, violas, and violins; and Blackbird Guitars' acoustic guitars and ukuleles; also audio components such as turntables and loudspeakers. *Firearms use it to replace certain metal, wood, and fiberglass components but many of the internal parts are still limited to metal alloys as current reinforced plastics are unsuitable. *High-performance drone bodies and other radio-controlled vehicle and aircraft components such as helicopter rotor blades. *Lightweight poles such as: tripod legs, tent poles, fishing rods, billiards cues, walking sticks, and high-reach poles such as for window cleaning. *Dentistry, carbon fiber posts are used in restoring root canal treated teeth. *Railed train
bogie A bogie ( ) (in some senses Sense relates to any of the systems and corresponding organs involved in sensation, i.e. the physical process of responding to Stimulus (physiology), stimuli and providing data for perception. During sensation, se ...
s for passenger service. This reduces the weight by up to 50% compared to metal bogies, which contributes to energy savings. *Laptop shells and other high performance cases. *Carbon woven fabrics. *Archery, carbon fiber arrows and bolts, stock, and rail. *As a filament for the 3D fused deposition modeling printing process, carbon fiber-reinforced plastic (polyamide-carbon filament) is used for the production of sturdy but lightweight tools and parts due to its high strength and tear length. *District heating pipe rehabilitation, using CIPP method.

# Disposal and recycling

CFRPs have a long service lifetime when protected from the sun. When it is time to decommission CFRPs, they cannot be melted down in air like many metals. When free of vinyl (PVC or
polyvinyl chloride Polyvinyl chloride (colloquial Colloquialism or colloquial language is the style (sociolinguistics), linguistic style used for casual (informal) communication. It is the most common functional style of speech, the idiom normally employed in ...
) and other halogenated polymers, CFRPs can be thermally decomposed via
thermal depolymerizationThermal depolymerization (TDP) is a depolymerization process using hydrous pyrolysis for the reduction of complex organic material Organic matter, organic material, or natural organic matter refers to the large source of carbon-based compounds ...
in an oxygen-free environment. This can be accomplished in a refinery in a one-step process. Capture and reuse of the carbon and monomers is then possible. CFRPs can also be milled or shredded at low temperature to reclaim the carbon fiber; however, this process shortens the fibers dramatically. Just as with downcycled paper, the shortened fibers cause the recycled material to be weaker than the original material. There are still many industrial applications that do not need the strength of full-length carbon fiber reinforcement. For example, chopped reclaimed carbon fiber can be used in consumer electronics, such as laptops. It provides excellent reinforcement of the polymers used even if it lacks the strength-to-weight ratio of an aerospace component.

# Carbon nanotube reinforced polymer (CNRP)

In 2009,
Zyvex Technologies Zyvex Technologies (formerly Zyvex Performance Materials, ZPM) is a molecular engineering company headquartered in Columbus, Ohio. Zyvex Technologies focuses on developing advanced materials, including prepreg, epoxy resins, and adhesives. History ...
introduced carbon nanotube-reinforced epoxy and carbon
pre-pregPre-preg is a composite material made from "pre-impregnated" fibers and a ''partially cured'' polymer matrix, such as epoxy or phenolic resin, or even thermoplastic A thermoplastic, or thermosoftening plastic, is a plastic polymer material that b ...
s.
Carbon nanotube image of a single-walled carbon nanotube. Carbon nanotubes (CNTs) are tubes made of carbon with diameters typically measured in nanometers The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI ...

reinforced polymer (CNRP) is several times stronger and tougher than CFRP and is used in the
Lockheed Martin F-35 Lightning II The Lockheed Martin F-35 Lightning II is an American family of single-seat, single-engine, all-weather Stealth aircraft, stealth multirole combat aircraft that is intended to perform both Air superiority fighter, air superiority and attack ...
as a structural material for aircraft. CNRP still uses carbon fiber as the primary reinforcement, but the binding matrix is a carbon nanotube-filled epoxy.

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