CARBON FIBERS.
Notes
CARBON FELTS are usually fabricated by CARBONIZATION of organic felts, but they can also be produced from short CARBON FIBERS.
See: CARBON FIBERS, CARBONIZATION.
Carbon Fiber
Description
CARBON FIBERS are fibers (filaments, tows, yarns, rovings) consisting of at least 92% (mass fraction) CARBON, usually in the NON‐GRAPHITIC stage.
See: CARBON, NON‐GRAPHITIC CARBON.
Notes
CARBON FIBERS are fabricated by pyrolysis of organic precursor fibers or by growth from gaseous hydrocarbons. The use of the term GRAPHITE FIBERS instead of CARBON FIBERS as often observed in literature is incorrect and should be avoided. The term GRAPHITE FIBERS is justified only if three‐dimensional crystalline order is confirmed, e.g. by X‐ray diffraction measurements.
See: GRAPHITE FIBERS.
Carbon Fiber Fabrics
Description
CARBON FIBER FABRICS are woven textile materials made of CARBON FIBERS.
See: CARBON FIBERS.
Carbon Fibers Type HM
Description
CARBON FIBERS TYPE HM (HIGH MODULUS) are CARBON FIBERS with a value of Young’s modulus (tensile modulus) larger than 300 GPa (nearly 30% of the C11 elastic constant of a graphite single crystal).
See: CARBON FIBERS.
Notes
The level of the tensile modulus of CARBON FIBERS is controlled by the degree of preferred orientation of the layer planes in the direction parallel to the fiber axis. C11, the elastic constant of graphite single crystals in the direction of the layer planes, is 1060 ± 20 GPa.
In general, the ratio of tensile strength to tensile modulus is smaller than 1 × 10−2 for CARBON FIBERS TYPE HM (but the tensile strength is influenced by flaws in the fibers and may be improved in the future).
CARBON FIBERS TYPE UHM (ULTRAHIGH MODULUS) have moduli of elasticity in excess of 600 GPa, surpassing 50% of the theoretical C11 number. Such high values of Young’s modulus can be achieved most readily in MESOPHASE PITCH‐BASED CARBON FIBERS (MPP‐BASED CARBON FIBERS).
See: 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
