FILMS is a synonym for DIAMOND‐LIKE CARBON FILMS.
See: DIAMOND‐LIKE CARBON FILMS.
Hexagonal Graphite
Description
HEXAGONAL GRAPHITE is the thermodynamically stable form of GRAPHITE with an ABAB stacking sequence of the GRAPHENE LAYERS. The exact crystallographic description of this allotropic form is given by the space group D46h‐P63/mmc (unit cell constants: ao = 245.6 pm, co = 670.8 pm). HEXAGONAL GRAPHITE is thermodynamically stable below approximately 2600 K and 6 GPa.
See: GRAPHENE LAYERS, GRAPHITE.
Notes
The use of the term GRAPHITE instead of the more exact term HEXAGONAL GRAPHITE may be tolerated in view of the minor importance of RHOMBOHEDRAL GRAPHITE, the other allotropic form.
See: GRAPHITE, RHOMBOHEDRAL GRAPHITE.
High‐Pressure Graphitization
Description
HIGH‐PRESSURE GRAPHITIZATION refers to a solid state transformation of NON‐GRAPHITIC CARBON into GRAPHITE by heat treatment under elevated pressure (e.g. 100–1000 MPa) so that a definitely higher degree of GRAPHITIZATION is achieved at lower temperature and/or for a shorter heat treatment time than in heat treatment of the same NON‐GRAPHITIC material at atmospheric pressure.
See: GRAPHITE, GRAPHITIZATION, NON‐GRAPHITIC CARBON.
Highly Oriented Pyrolytic Graphite
Description
HIGHLY ORIENTED PYROLYTIC GRAPHITE (HOPG) is a PYROLYTIC GRAPHITE with an angular spread of the c‐axes of crystallites of less than 1°.
See: GRAPHITE, PYROLYTIC GRAPHITE.
Notes
Commercial HIGHLY ORIENTED PYROLYTIC GRAPHITE is usually produced by stress annealing at approximately 3300 K.
Isotropic Carbon
Description
ISOTROPIC CARBON is a monolithic CARBON MATERIAL without preferred crystallographic orientation of the microstructure.
See: CARBON MATERIAL.
Notes
ISOTROPIC CARBON can also be a GRAPHITE MATERIAL. The isotropy can be gross (bulk), macroscopic, or microscopic depending on the structural level at which isotropy is obtained. This word is widely used today and its meaning covers all the above levels. For example, the aerospace graphites have isotropy built in by random grain orientation. Some NUCLEAR GRAPHITES are isotropic at the crystalline (sub‐grain) level.
See: GRAPHITE MATERIAL, NUCLEAR GRAPHITE.
Isotropic Pitch‐Based Carbon Fibers
Description
ISOTROPIC PITCH‐BASED CARBON FIBERS are CARBON FIBERS obtained by CARBONIZATION of isotropic pitch fibers after these have been stabilized (i.e. made non‐fusible).
See: CARBON FIBERS, CARBONIZATION, PITCH‐BASED CARBON FIBERS, STABILIZATION TREATMENT
Notes
During fabrication of ISOTROPIC PITCH‐BASED CARBON FIBERS, no means (neither mechanical nor chemical) are applied to achieve preferred orientation of the polyaromatic molecules in the fiber direction. They belong to the CARBON FIBERS TYPE LM (LOW MODULUS), and because of the relatively low values of strength and Young’s modulus, this PITCH‐BASED CARBON FIBER type is not used for high‐performance reinforcement purposes.
See: CARBON FIBERS TYPE LM, PITCH‐BASED CARBON FIBERS.
Lamp Black
Description
LAMP BLACK is a special type of CARBON BLACK produced by incomplete combustion of a fuel, rich in aromatics that are burned in flat pans. LAMP BLACK is characterized by a relatively broad particle size distribution.
See: CARBON BLACK.
Mesogenic Pitch
Description
MESOGENIC PITCH is a PITCH with a complex mixture of numerous essentially aromatic hydrocarbons. It does not contain anisotropic particles detectable by optical microscopy. MESOGENIC PITCH is low in quinoline‐insoluble fractions and capable of transforming into MESOPHASE PITCH during continuous heat treatment above 750 K by the formation of optically detectable CARBONACEOUS MESOPHASE.
See: CARBONACEOUS MESOPHASE, MESOPHASE PITCH, PITCH.
Mesophase Pitch
Description
MESOPHASE PITCH is a PITCH with a complex mixture of numerous essentially aromatic hydrocarbons containing anisotropic liquid‐crystalline particles (CARBONACEOUS MESOPHASE) detectable by optical microscopy and capable of coalescence into the BULK MESOPHASE.
See: BULK MESOPHASE, CARBONACEOUS MESOPHASE, MESOGENIC PITCH, PITCH.
Notes
The CARBONACEOUS MESOPHASE particles are formed from the aromatics of high molecular mass in MESOGENIC PITCH, which have not yet been aggregated to particles detectable by optical microscopy within the apparently isotropic PITCH matrix. The CARBONACEOUS MESOPHASE is insoluble in quinoline and pyridine, but the amount of mesophase measured from microscopical observation appears somewhat higher because parts of the CARBONACEOUS MESOPHASE can be extracted by the solvents.
See: CARBONACEOUS MESOPHASE, MESOGENIC PITCH, PITCH.
Mesophase Pitch‐Based
