Industrial Carbon and Graphite Materials. Группа авторов
CARBON FIBERS, CARBON FIBERS TYPE UHM, MESOPHASE PITCH‐BASED CARBON FIBERS.
Carbon Fibers Type HT
Description
CARBON FIBERS TYPE HT are CARBON FIBERS with values of Young’s modulus between 150 and 275–300 GPa. The term HT, referring to high tensile strength, was early applied because fibers of this type display the highest tensile strengths.
See: CARBON FIBERS.
Notes
The disposition of boundaries between the fiber types is somewhat arbitrary.
For CARBON FIBERS TYPE HT, the values of the strength‐to‐stiffness ratio are typically larger than 1.5 × 10−2. The tensile strength of CARBON FIBERS is flaw‐controlled, however, and therefore the measured values increase strongly as the diameter of the filaments is decreased.
See: CARBON FIBERS, CARBON FIBERS TYPE IM.
Carbon Fibers Type IM
Description
The CARBON FIBERS TYPE IM (INTERMEDIATE MODULUS) are related to CARBON FIBERS TYPE HT because of the comparable values of tensile strength but are characterized by greater stiffness (Young’s modulus up to approximately 35% of the theoretical C11 value).
See: CARBON FIBERS, CARBON FIBERS TYPE HT.
Notes
The tensile modulus (Young’s modulus) varies between approximately 275 and 300 GPa, but the disposition of the boundaries is somewhat arbitrary. The relatively high ratio of tensile strength to tensile modulus, typically above 1 × 10−2, in CARBON FIBERS TYPE IM, in spite of an increase of Young’s modulus, requires a further increase of strength, which is achievable by a significant reduction of the monofilament diameter down to about 5 μm. Such small filament diameters are typical of CARBON FIBERS TYPE IM.
Carbon Fibers Type LM (Low Modulus)
Description
CARBON FIBERS TYPE LM (LOW MODULUS) are CARBON FIBERS with isotropic structure, tensile modulus values as low as 10% of the C11 values of the graphite single crystal, and low strength values.
See: CARBON FIBERS.
Notes
The term CARBON FIBERS TYPE LM (LOW MODULUS) is sometimes used for various types of isotropic CARBON FIBERS known as PITCH‐BASED or RAYON‐BASED CARBON FIBERS that have not been subjected to hot‐stretching. Such fibers are not used for reinforcement purposes in high‐performance composites.
See: CARBON FIBERS, PITCH‐BASED CARBON FIBERS, RAYON‐BASED CARBON FIBERS.
Carbon Fibers Type UHM
Description
CARBON FIBERS TYPE UHM (ULTRAHIGH MODULUS) designates a class of CARBON FIBERS having very high values of Young’s modulus larger than 600 GPa (i.e. greater than 55% of the theoretical C11 value of GRAPHITE).
See: CARBON FIBER, CARBON FIBERS TYPE HM, GRAPHITE.
Carbon Material
Description
CARBON MATERIAL is a solid high in content of the element CARBON and structurally in a NON‐GRAPHITIC state.
See: CARBON, NON‐GRAPHITIC CARBON.
Notes
The use of the term CARBON as a short term for a material consisting of NON‐GRAPHITIC CARBON is incorrect. The use of the term CARBON without a second noun or a clarifying adjective should be restricted to the chemical element carbon. The term CARBON can be used in combination with other nouns or clarifying adjectives for special types of CARBON MATERIALS (CARBON ELECTRODE, CARBON FIBERS, PYROLYTIC CARBON, GLASS‐LIKE CARBON, and others).
See: CARBON, CARBON ELECTRODE, CARBON FIBERS, GLASS‐LIKE CARBON, NON‐GRAPHITIC CARBON, PYROLYTIC CARBON.
Carbon Mix
Description
CARBON MIX is a mixture of FILLER COKE, e.g. grains and/or powders of solid CARBON MATERIALS, and a carbonaceous BINDER and selected additives prepared in heated mixers at temperatures in the range of 410–445 K as a preliminary step for the formation of shaped green bodies.
See: BINDER, CARBON MATERIAL, FILLER COKE.
Carbon Whiskers
Description
See: GRAPHITE WHISKERS.
Carbonaceous Mesophase
Description
CARBONACEOUS MESOPHASE is a liquid‐crystalline state of PITCH, which shows the optical birefringence of disklike (discotic) nematic liquid crystals. It can be formed as an intermediate phase during thermolysis (pyrolysis) of an isotropic molten PITCH or by precipitation from PITCH fractions prepared by selective extraction. Generally, the spherical mesophase precipitated from a pyrolyzing PITCH has the BROOKS AND TAYLOR STRUCTURE. With continuous heat treatment the CARBONACEOUS MESOPHASE coalesces to a state of BULK MESOPHASE before solidification to GREEN COKE with further loss of hydrogen or low‐molecular‐weight compounds.
See: BROOKS AND TAYLOR STRUCTURE IN THE CARBONACEOUS MESOPHASE, BULK MESOPHASE, GREEN COKE, PITCH.
Notes
In the formation of CARBONACEOUS MESOPHASE by thermolysis (pyrolysis) of isotropic molten PITCH, the development of a liquid‐crystalline phase is accompanied by simultaneous aromatic polymerization reactions. The reactivity of PITCH with increasing heat treatment temperature and its thermosetting nature are responsible for the lack of a true reversible thermotropic phase transition for the BULK MESOPHASE in most PITCHES. Due to its glass‐like nature, most of the liquid‐crystalline characteristics are retained in the supercooled solid state.
See: BROOKS AND TAYLOR STRUCTURE IN THE CARBONACEOUS MESOPHASE, BULK MESOPHASE, PITCH.
Carbonization
Description
CARBONIZATION is a process by which solid residues with increasing content of the element carbon are formed from organic material usually by pyrolysis in inert atmosphere.
Notes
As with all pyrolytic reactions, CARBONIZATION is a complex process in which many