Industrial Carbon and Graphite Materials. Группа авторов
COKE is mainly produced from tars or residues from petrochemistry by the DELAYED COKING PROCESS. Also refined COAL‐TAR PITCHES are used as precursors for PREMIUM COKE production.
See: COAL‐TAR PITCH, DELAYED COKING PROCESS, REGULAR COKE.
Puffing
Description
The term PUFFING describes an irreversible expansion of some CARBON ARTIFACTS during GRAPHITIZATION HEAT TREATMENT between 1650 and 2700 K.
See: CARBON ARTIFACT, COKE, GRAPHITIZATION HEAT TREATMENT.
Notes
PUFFING is caused by the release of heteroatoms, for instance, sulfur atoms, from the COKE in association with specific microstructural rearrangements.
See: COKE, POLYGRANULAR CARBON, PUFFING INHIBITOR.
Puffing Inhibitor
Description
PUFFING INHIBITORS are metals or metal compounds with a high chemical affinity for the heteroatoms in the carbons. They are distributed as fine particles within the CARBON MATERIALS to be graphitized.
See: CARBON MATERIAL.
Notes
Iron and iron compounds are most frequently used as PUFFING INHIBITORS when PUFFING is related to sulfur.
See: PUFFING.
Pyrolytic Carbon
Description
PYROLYTIC CARBON is a CARBON MATERIAL deposited from gaseous hydrocarbon compounds on suitable underlying substrates (CARBON MATERIALS, metals, ceramics) at temperatures ranging from 1000 to 2500 K (chemical vapor deposition).
See: CARBON MATERIAL.
Notes
A wide range of microstructures, e.g. isotropic, lamellar, substrate‐nucleated, and varied content of remaining hydrogen, can occur in PYROLYTIC CARBONS, depending on the deposition conditions (temperature, type, concentration, and flow rate of the source gas, surface area of the underlying substrate, etc.).
“Pyrocarbon” that is synonymous with PYROLYTIC CARBON was introduced as a trademark and should not be used as a term.
The term PYROLYTIC CARBON does not describe the large range of CARBON MATERIALS obtained by thermal degradation (thermolysis, pyrolysis) of organic compounds when they are not formed by chemical vapor deposition (CVD). Also CARBON MATERIALS, obtained by physical vapor deposition (PVD), are not covered by the term PYROLYTIC CARBON.
See: CARBON MATERIAL.
Pyrolytic Graphite
Description
PYROLYTIC GRAPHITE is a GRAPHITE MATERIAL with a high degree of preferred crystallographic orientation of the c‐axes perpendicular to the surface of the substrate, obtained by GRAPHITIZATION HEAT TREATMENT of PYROLYTIC CARBON or by chemical vapor deposition at temperatures above 2500 K.
See: GRAPHITE MATERIAL, GRAPHITIZATION HEAT TREATMENT, PYROLYTIC CARBON.
Notes
“Pyrographite,” a synonym for PYROLYTIC GRAPHITE, was introduced as a trademark and should not be used as term.
Hot working of PYROLYTIC GRAPHITE (by heat treatment under compressive stress at temperatures above 3000 K) results in HIGHLY ORIENTED PYROLYTIC GRAPHITE (HOPG).
See: HIGHLY ORIENTED PYROLYTIC GRAPHITE.
Raw Coke
Description
See: GREEN COKE.
Notes
The term RAW COKE is equivalent to GREEN COKE although it now used less frequently.
See: GREEN COKE.
Rayon‐Based Carbon Fibers
Description
RAYON‐BASED CARBON FIBERS are CARBON FIBERS made from rayon (cellulose) precursor fibers.
See: CARBON FIBERS.
Notes
RAYON‐BASED CARBON FIBERS have a more isotropic structure than similarly heat‐treated polyacrylonitrile (PAN)‐ or MESOPHASE PITCH‐BASED (MPP‐BASED) CARBON FIBERS. Their Young’s modulus values are therefore drastically lower (Youngs modulus, E < 100 GPa; tensile strength, σ > 100 MPa). RAYON‐BASED CARBON FIBERS can be transformed into anisotropic CARBON FIBERS with high strength and Young’s modulus values by hot‐stretching treatment at temperatures of approximately 2800 K.
See: CARBON FIBERS, MESOPHASE PITCH‐BASED CARBON FIBERS, PAN‐BASED CARBON FIBERS.
Regular Coke
Description
REGULAR COKE is a PETROLEUM COKE with good graphitizability and is characterized by a combination of properties that differ significantly from those of METALLURGICAL COKE but do not reach the quality level of PREMIUM COKE. These properties are optical anisotropy, medium reversible thermal expansion, and low ash content.
See: METALLURGICAL COKE, PETROLEUM COKE, PREMIUM COKE.
Notes
Typical characteristics for REGULAR COKE in comparison with those of METALLURGICAL COKE and of PREMIUM COKE calcined at 1620 K are:
| Regular coke | Premium coke | Metallurgical coke | |
| Real densitya) (g × cm−3) | 2.07–2.09 | 2.12–2.14 | 1.95–2.02 |
| CTEb) (293–773 K) (K−1) | 2.0 × 10−6 | 1.1 × 10−6 | >3.0 × 10−6 |
|
CTEb) |