Industrial Carbon and Graphite Materials. Группа авторов
K) (K−1)
a) Measured with m‐xylene.
b) Coefficient of thermal expansion.
REGULAR COKE is mainly used for the production of SYNTHETIC CARBON and GRAPHITE MATERIALS.
See: CARBON MATERIAL, GRAPHITE MATERIAL, METALLURGICAL COKE, PREMIUM COKE, SYNTHETIC GRAPHITE.
Rhombohedral Graphite
Description
RHOMBOHEDRAL GRAPHITE is a thermodynamically unstable allotropic form of GRAPHITE with an ABCABC stacking sequence of the layers. The exact crystallographic description of this allotropic form is given by the space group D53d‐R3m (unit cell constants: a = 256.6 pm, c = 1006.2 pm).
See: GRAPHITE.
Notes
The structure of RHOMBOHEDRAL GRAPHITE can be best considered as an extended stacking fault in HEXAGONAL GRAPHITE. RHOMBOHEDRAL GRAPHITE cannot be isolated in pure form (NATURAL GRAPHITE and laboratory preparations contain less than 40% of RHOMBOHEDRAL GRAPHITE in combination with HEXAGONAL GRAPHITE). It is produced by shear deformation of HEXAGONAL GRAPHITE and transforms progressively to the hexagonal (ABAB) modification on heating above 1600 K.
See: HEXAGONAL GRAPHITE, NATURAL GRAPHITE.
Semicoke
Description
SEMICOKE is a carbonaceous material intermediate between a fusible MESOPHASE PITCH and a non‐deformable GREEN COKE produced by incomplete CARBONIZATION at temperatures between the onset of fusion (of coal, approximately 620 K), and complete devolatilization. SEMICOKE still contains volatile matter, therefore.
See: CARBONIZATION, COAL‐TAR PITCH, GREEN COKE, MESOPHASE PITCH.
Notes
SEMICOKE may be conceived as covering a continuous range from coal that has not yet been fused to COKE BREEZE. SEMICOKE can also be used as a FILLER in carbon mixtures.
See: COKE BREEZE, FILLER.
Soot
Description
SOOT is a randomly formed PARTICULATE CARBON material and may be coarse, fine, and/or colloidal in proportions dependent on its origin. SOOT consists of variable quantities of carbonaceous and inorganic solids together with absorbed and occluded tars and resins.
See: PARTICULATE CARBON.
Notes
SOOT is generally formed as an unwanted by‐product of incomplete combustion or pyrolysis. SOOT generated within flames consists essentially of aggregates of spheres of carbon. SOOT found in domestic fireplace chimneys contains few aggregates but may contain substantial amounts of particulate fragments of COKE or CHAR. SOOT from diesel engines consists essentially of aggregates together with tars and resins. For historical reasons, the term SOOT is sometimes incorrectly used for CARBON BLACK. This misleading use should be avoided.
See: CARBON BLACK, CHAR, COKE.
Spherical Carbonaceous Mesophase
Description
The term SPHERICAL CARBONACEOUS MESOPHASE describes the morphology of CARBONACEOUS MESOPHASE, which is formed in the isotropic PITCH matrix. The SPHERICAL CARBONACEOUS MESOPHASE usually has a lamellar structure consisting of flat aromatic molecules arranged in parallel layers that are perpendicular to the sphere/isotropic phase interface as described by BROOKS AND TAYLOR. On coalescence, this spherical mesophase loses its characteristic morphology and is converted to the BULK MESOPHASE.
See: BROOKS AND TAYLOR STRUCTURE, BULK MESOPHASE, CARBONACEOUS MESOPHASE, PITCH.
Stabilization Treatment of Thermoplastic Precursor Fibers for Carbon Fibers
Description
STABILIZATION TREATMENT is a process applied to fusible organic precursor fibers for CARBON FIBERS with the aim of obtaining non‐fusible polymer fibers suitable for subsequent CARBONIZATION. The original fiber shape is maintained.
See: CARBON FIBERS, CARBONIZATION.
Notes
The STABILIZATION TREATMENT of thermoplastic precursor fibers for CARBON FIBERS is usually a heat treatment process performed in an oxidizing atmosphere above 470 K. For STABILIZATION TREATMENT of polyacrylonitrile (PAN) fibers, 600 K is the highest temperature up to which cyclization, dehydrogenation, and oxidation processes prevail.
See: CARBON FIBERS.
Stress Graphitization
Description
STRESS GRAPHITIZATION refers to the solid state transformation of NON‐GRAPHITIC CARBON into GRAPHITE by heat treatment combined with application of mechanical stress, resulting in a defined degree of GRAPHITIZATION being obtained at lower temperature and/or for a shorter time of heat treatment than in the absence of applied stress.
See: GRAPHITE, GRAPHITIZATION, NON‐GRAHITIC CARBON.
Notes
STRESS GRAPHITIZATION may also occur in volume elements of a carbon body in the process of heat treatment as a result of the action of internal residual or thermal stresses.
Synthetic Graphite
Description
SYNTHETIC GRAPHITE is a material consisting of GRAPHITIC CARBON that has been obtained by graphitizing of NON‐GRAPHITIC CARBON, by chemical vapor deposition (CVD) from hydrocarbons at temperatures above 2500 K, by decomposing of thermally unstable carbides, or by crystallizing from metal melts supersaturated with carbon.
See: GRAPHITIC CARBON, GRAPHITIZATION, NON‐GRAPHITIC