Graphitization


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graphitization

[‚graf·əd·ə′zā·shən]
(organic chemistry)
The formation of graphitelike material from organic compounds.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Graphitization

 

the formation (deposition) of graphite in iron, nickel, cobalt, and other metal alloys in which carbon is contained in the form of unstable chemical compounds, carbides. At high temperatures the carbide is completely replaced by graphite. The rate of graphitization increases upon a rise in temperature, as well as upon preliminary hardening, deformation, and irradiation.

Graphitization of steel usually adversely affects the mechanical properties of steel (it reduces the strength and plasticity). At the same time the graphite, which has lubricating properties, increases the durability of the articles. The graphitization of iron alloys is used in producing articles from cast iron and graphitic bearing and die steel. Silicon, or less frequently aluminum, is introduced into steel or iron to accelerate graphitization. The graphitization of a number of alloys (tool-cutting, spring, boiler, and other steels) reduces their operating quality and is undesirable. Graphitization can be arrested by introducing additives (chromium or manganese), which increase the stability of the carbides. The term “graphitization” is sometimes used to designate the formation of graphite in iron-carbon alloys that do not contain carbides. Graphite is separated from alloys that are supersaturated with carbon upon their solidification and subsequent cooling.

REFERENCES

Grafitizatsiia stali. Kiev, 1961.
Girshovich, N. G. Kristallizatsiia i svoislva chuguna ν otlivkakh. Moscow-Leningrad, 1966.
Krishtal, M. A., and E. G. Titenskii. Svoistva kovkogo chuguna. Moscow, 1967.

K. P. BUNIN and A. A. BARANOV

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Reviewing literature, the oxidation corrosion rate of graphite was not only determined by its degree of graphitization but also influenced by the content of impurity elements such as the Fe, Cr, and Co that would act as the catalysts in the oxidation process in the MG [9, 10].
Wang, "A study on graphitization of diamond in copper-diamond composite materials," Materials Letters, vol.
By tuning the carbonization temperature and KOH/C ratio, Konjac sponge-derived ACs (KACs) with ultrahigh SSA (up to ~3000 [m.sup.2]/g at KOH/C > 3), tunable micro/mesopore volume, varied O/N doping, and high graphitization degree have been achieved.
Indeed, a higher nanotube graphitization degree was proved by Raman spectroscopy, i.e., lower I(D)/I(G) ratio, when the temperature during the growth was increased from 600 to 650 and 700[degrees]C (Figure 4(b)).
The Raman spectra indicates high graphitization of carbons supports which is related high electric conductivity.
Zhu, "Effect of microstructure on the mechanical properties of PAN-based carbon fibers during high-temperature graphitization," Journal of Materials Science, vol.
Moreover, many reports indicate that [alpha]-ZrP are also able to catalyze carbonization and graphitization on the surface of polymer composites [16-21].
The equivalent reflectivity of solid bitumen can be calculated through the equation " [sub.Rmc][R.sub.o]% = 1.1659h (Dh/Gh) + 2.7588" (where h (Dh/Gh) is the ratio of peak height of peaks G and D), which is suitable for thermal evolution stage from overmature to granular graphitization.
At around 200[degrees]C starts a so called "graphitization" of the carbon which implies the transformation of [sp.sup.3] in [sp.sup.2] bonding (graphite like) and this leads to a quick wear of the coating, see figure 7.
(4) The treatment results in a high degree of graphitization of the laminates with little structural damage, and the resultant films are highly impermeable to gases, liquids, and aggressive chemicals, including hydrofluoric acid.
It is characterized by the lower ash, moisture and volatile contents (below 0.25 wt %) than a steam coal, but generally contains higher sulfur quantities; 2) RGC - resilient graphitic carbons, which is one of the most unique graphitic carbons available nowadays with the carbon content of 99.9 wt.%, and the degree of graphitization being about 80%; and 3) synthetic graphite that is produced by graphitization of petroleum and coal tar-based cokes at temperatures above 2500[degrees]C under exclusion of oxygen.
Some of the samples showed dark areas of graphitization on their girdles (Figure 6).