Composites carbon/graphite fiber

Delmonte, J. (1981). Surface treatments of carbon/graphite fibers and their effect on composites. In Technology of Carbon and Graphite Fiber Composites. Van Nostrand Reinhold, New York, pp. 171-197. 

Synthetics and mineral fibers have other parallels. A few synthesized fibers show a higher level or secondary ordering of the crystalline structure, such as that described for chrysotile. Composed entirely of carbon, graphite fibers are synthetic fibers with such a secondary structure (see the following section). Tubular fibers of other compositions, such as aluminum silicate polymers, have also been synthesized (Farmer et al., 1977). 

Ceramic fibers used in composites are usually made by high-temperature methods. Carbon (graphite) fiber, for example, can be made by the thermal decomposition of fibers of polyacrylonitrile, a long-chain organic molecule also used to make the textile Orion ... 

Elemental carbon is usually handled in three forms graphite, diamond, and amorphous carbon. Graphite and amorphous carbon have been extensively used in electrochemistry because of their high electrical conductivity, chemical stability, versatility, and low cost. For electrochemical applications, such materials can be manufactured in bars, powders, and fibers or can even form conducting composites when appropriate binders are used. A number of carbon-based materials, such as pyrolytic carbon, carbon blacks, activated carbons, graphite fibers, whiskers, glassy carbon, etc., have been used in electrochemistry for decades (Yoshimura and Chang, 1998). 

Composite materials that take advantage of the strength, stability, and low density of carbon fibers are widely used. Composites are combinations of two or more materials. These materials are present as separate phases and are combined to form structures that take advantage of certain desirable properties of each component. In carbon composites the graphite fibers are often woven into a fabric that is embedded in a matrix that binds them into a soUd structure. The... 

Balaba WM, Weirauch DA, Perrotta AJ, Armstrong GH, Anyalebechi PN, Kauffman S, MacInnes AN, Winner AM, Barron AR, Effect of sUoxane spin-on-glass and reaction bonded silicon oxycarbide coatings with a self-propagating interfacial reaction treatment (aspire) in the synthesis of carbon/graphite fiber-reinforced A1 metal matrix composites, J Mater Res, 8(12), 3192-3201, 1993. 

Chen Y, Zhang GD, Wu F, Zhu J, Study of the C/Mg interface in magnesium matrix composites reinforced by carbon (graphite) fiber, Rare Metal Mater Eng, 26(3), 20-25, 1997. 

Phenolic resins give a high char yield on combustion and TGA provides a measure of the expected yield. Typical values are between 40 and 65% in nitrogen. Decomposition begins at 350°C and continues up to 600°C. Autoignition temperature in air is above 900°C. Thermogravimetric analyses have played an important part in the development of carbon-carbon and carbon-graphite-fiber composites... 

Carbon/graphite. Carbon/graphite fibers have demonstrated the widest variety of strengths and moduli and have the greatest number of suppliers (Tables 4.4a and 4.4b). The carbon/graphite fiber manufacturers, as a result of the turmoil in the composite... 

Most of the reported data in the field were focused on epoxy resins based composites, either filled with microparticles, such as Ti02 containing pigments [213] and glass microspheres [214], or glass or carbon/graphite fiber reinforced [215-221]. 

Carbon-Carbon Composites. Carbon—carbon composites are simply described as a carbon fiber reinforcement in one or many directions using a carbon or graphite matrix material (see Composite materials). 

Carbon—carbon composites for rocket nozzles or exit cones are usually made by weaving a 3D preform composed of radial, axial, and circumferential carbon or graphite fibers to near net shape, followed by densification to high densities. Because of the high relative volume cost of the process, looms have been designed for semiautomatic fabrication of parts, taking advantage of selective reinforcement placement for optimum thermal performance. 

High performance composites may be laminates wherein veils of carbon fiber ate treated with an epoxy resin, stacked up to the desired final product thickness, and then laminated together under heat and pressure (see Composite materials Carbon and graphite fibers). Simply mixing together carbon or glass fibers and polymeric resins to form a reinforced plastic leads to a composite material, but this is not a laminate if not constmcted from discrete phes. 

Carbon—carbon composites are used in high temperature service for aerospace and aircraft appHcations as weU as for corrosion-resistant industrial pipes and housings. AppHcations include rocket nozzles and cases, aircraft brakes, and sateUite stmctures. Carbonized phenoHc resin with graphite fiber functioned effectively as the ablative shield in orbital re-entry vehicles for many years (92). 

Carbon, Carbides, and Nitrides. Carbon (graphite) is a good thermal and electrical conductor. It is not easily wetted by chemical action, which is an important consideration for corrosion resistance. As an important stmctural material at high temperature, pyrolytic graphite has shown a strength of 280 MPa (40,600 psi). It tends to oxidize at high temperatures, but can be used up to 2760°C for short periods in neutral or reducing conditions. The use of new composite materials made of carbon fibers is expected, especially in the field of aerospace stmcture. When heated under... 

For friction material appHcations, composite materials (qv) comprising glass or metallic fibers with other minerals have been developed. In such appHcations also, aramid and graphite fibers are effective, although the cost of these materials restricts their use to heavy duty or high technology appHcations (see Carbon fibers). 

Carbon Composites. In this class of materials, carbon or graphite fibers are embedded in a carbon or graphite matrix. The matrix can be formed by two methods chemical vapor deposition (CVD) and coking. In the case of chemical vapor deposition (see Film deposition techniques) a hydrocarbon gas is introduced into a reaction chamber in which carbon formed from the decomposition of the gas condenses on the surface of carbon fibers. An alternative method is to mold a carbon fiber—resin mixture into shape and coke the resin precursor at high temperatures and then foUow with CVD. In both methods the process has to be repeated until a desired density is obtained. 

More than 95% of current carbon fiber production for advanced composite appHcations is based on the thermal conversion of polyacrylonitrile (PAN) or pitch precursors to carbon or graphite fibers. Generally, the conversion of PAN or pitch precursor to carbon fiber involves similar process steps fiber formation, ie, spinning, stabilization to thermoset the fiber, carbonization—graphitization, surface treatment, and sizing. Schematic process flow diagrams are shown in Eigure 4. However, specific process details differ. 

A polymer blend is a physical or mechanical blend (alloy) of two or more homopolymers or copolymers. Although a polymer blend is not a copolymer according to the above definition, it is mentioned here because of its commercial importance and the frequency with which blends are compared with chemically bonded copolymers. Another technologically significant material relative to the copolymer is the composite, a physical or mechanical combination of a polymer with some unlike material, eg, reinforcing materials such as carbon black, graphite fiber, and glass (see Composite materials). 

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