Industrial Carbon and Graphite Materials. Группа авторов
PETROLEUM COKE is a CARBONIZATION product of high‐boiling hydrocarbon fractions obtained in petroleum processing (heavy residues). It is the general term for all special PETROLEUM COKE products such as GREEN, CALCINED, and NEEDLE petroleum COKE.
See: CALCINED COKE, CARBONIZATION, GREEN or RAW COKE, NEEDLE COKE.
Notes
High‐boiling hydrocarbon fractions (heavy residues) used as feedstock for PETROLEUM COKE are residues from distillation (atmospheric, vacuum) or cracking (e.g. thermal, catalytic, steam‐based) processes. The nature of feedstock has a decisive influence on the graphitizability of the CALCINED COKE.
See: CALCINED COKE.
Petroleum Pitch
Description
PETROLEUM PITCH is a residue from heat treatment and distillation of petroleum fractions. It is solid at room temperature, consists of a complex mixture of numerous predominantly aromatic and alkyl‐substituted aromatic hydrocarbons, and exhibits a broad softening range instead of a defined melting temperature.
Notes
The hydrogen aromaticity (ratio of aromatic to total hydrogen atoms) varies between 0.3 and 0.6. The aliphatic hydrogen atoms are typically present in alkyl groups substituted on aromatic rings or as naphthenic hydrogen.
Pitch
Description
PITCH is a residue from pyrolysis of organic material or tar distillation, which is solid at room temperature, consisting of a complex mixture of numerous, essentially aromatic hydrocarbons and heterocyclic compounds. It exhibits a broad softening range instead of a defined melting temperature. When cooled from the melt, PITCHES solidify without crystallization.
Notes
The ratio of aromatic to aliphatic hydrogen depends mainly on the source of the starting material. The hydrogen aromaticity (ratio of aromatic to total hydrogen atoms) varies between 0.3 and 0.9.
The aliphatic hydrogen in PITCH is largely associated with alkyl side chains substituted on aromatic rings. The content of heterocyclic compounds in pitches varies depending on their origins. Also the softening temperature can vary in a broad range between about 320 and 570 K depending on the molecular weight (relative molecular mass) and composition of the constituents.
Pitch‐Based Carbon Fibers
Description
PITCH‐BASED CARBON FIBERS are CARBON FIBERS obtained from PITCH precursor fibers after STABILIZATION TREATMENT, CARBONIZATION, and final heat treatment.
See: CARBON FIBERS, CARBONIZATION, PITCH, STABILIZATION TREATMENT.
Notes
The term PITCH‐BASED CARBON FIBERS comprises the ISOTROPIC PITCH‐BASED CARBON FIBERS as well as the anisotropic MESOPHASE PITCH‐BASED CARBON FIBERS (MPP‐BASED CARBON FIBERS). The isotropic type belongs to the CARBON FIBERS TYPE LM (LOW MODULUS) and is mainly used as filler in polymers and insulation materials and for similar applications. The anisotropic type (MPP‐BASED CARBON FIBERS) belongs to the CARBON FIBERS TYPE HM and is used mainly for reinforcement purposes due to its high Young’s modulus value.
See: CARBON FIBERS TYPE HM, CARBON FIBERS TYPE LM (LOW MODULUS), ISOTROPIC PITCH‐BASED CARBON FIBERS, MESOPHASE PITCH‐BASED CARBON FIBERS.
Polycrystalline Graphite
Description
POLYCRYSTALLINE GRAPHITE is a GRAPHITE MATERIAL with coherent crystallographic domains of limited size regardless of the perfection and preferred orientation (texture) of their crystalline structure.
See: GRAPHITE MATERIAL.
Notes
The common use of the term POLYCRYSTALLINE GRAPHITE for POLYGRANULAR GRAPHITE is in line with this definition but may be inexact because usually all grains of POLYGRANULAR GRAPHITE are polycrystalline themselves.
POLYCRYSTALLINE GRAPHITE can exhibit a random orientation, more or less preferred orientation, or a highly oriented texture as in some PYROLYTIC GRAPHITES.
There is no sharp transition, however, between the typical polycrystalline texture and the “single crystal‐like” texture of HIGHLY ORIENTED PYROLYTIC GRAPHITE (HOPG).
See: HIGHLY ORIENTED PYROLYTIC GRAPHITE, POLYGRANULAR GRAPHITE, PYROLYTIC GRAPHITE.
Polygranular Carbon
Description
POLYGRANULAR CARBON is a CARBON MATERIAL composed of grains, which can be clearly distinguished by means of optical microscopy.
See: CARBON MATERIAL.
Notes
Industrial CARBON MATERIALS (such as electrodes) are mostly polygranular, but special grades are agranular materials, such as GLASS‐LIKE CARBON, CARBON FIBERS, or PYROLYTIC CARBON. Such materials are covered by the term AGRANULAR CARBON.
See: AGRANULAR CARBON, CARBON FIBERS, CARBON MATERIAL, GLAS‐LIKE CARBON, PYROLYTIC CARBON
Polygranular Graphite
Description
POLYGRANULAR GRAPHITE is a GRAPHITE MATERIAL composed of grains, which can be clearly distinguished by means of optical microscopy.
See: GRAPHITE MATERIAL.
Notes
From the viewpoint of crystallinity, a POLYGRANULAR GRAPHITE is always a POLYCRYSTALLINE GRAPHITE, but not vice versa. Most industrial GRAPHITE MATERIALS are polygranular. Monogranular materials consist mostly of NON‐GRAPHITIC CARBON; such materials are called monolithic or AGRANULAR CARBONS.
See: AGRANULAR CARBON, GRAPHITE MATERIAL, NON‐GRAPHITIC CARBON, POLYCRYSTALLINE GRAPHITE.
Premium Coke
Description
PREMIUM COKE is an extremely well graphitizing carbon with a high degree of optical anisotropy (isochromatic areas of optical texture above about 100 μm) and is characterized by a combination of the following properties that differ significantly from those of REGULAR COKE: high real density, low reversible thermal expansion, and low ash content combined, in most cases, with low sulfur content.
See: REGULAR COKE.
Notes