Graphitizing heat-treatment

There is Htfle crystal growth during carbonization, which always occurs in the soHd phase. The soHd cross-linking that occurs at this time does not lend itself to crystal growth. The glassy carbons are composed of random crystaUites of the order of 5.0 nm across and are not significantly altered by ordinary graphitization heat treatment to 2800°C. 

Figure 27. Flexural strength and bulk density of unidirectional composites subjected to graphitizing heat treatments either for each densification cycle or after the densification cycles were completed (20,52) The matrix was a coal-tar binder pitch with 10 wt.-% sulfur the high-modulus PAN-based fiber was Sigrafil HM.

Degree of orientation Degree of graphitization Heat treatment temperature... 

Scheme I is a generalized scheme for the transformation of a polynuclear aromatic hydrocarbon to carbon and graphite. Heat treatment at about 350-500 °C leads to a complex reaction product mixture designated as pitch. Further reaction at temperatures near 500 °C results in an infusible polymeric hydrocarbon mixture designated as coke. As the heat-treatment process continues, the remaining hydrogen is removed, and a two-dimensional carbon polymer is formed. Finally, at temperatures near 3000 °C, three-dimensionally ordered graphite is produced.

Note GAS PHASE GROWN CARBON FIBERS transform during GRAPHITIZATION HEAT TREATMENT into GRAPHITE FIBERS. The term vapor grown carbon fibers is also acceptable but, CVD fibers is not acceptable, as it also describes fibers grown by a chemical vapor deposition (CVD) process on substrate fibers. 

Note GRAPHITE FIBERS can be obtained by GRAPHITIZATION HEAT TREATMENT of CARBON FIBERS, if these consist mostly of GRAPHITIZABLE CARBON. 

GRAPHITIZED CARBON is a GRAPHITIC CARBON with more or less perfect three-dimensional hexagonal crystalline order, prepared from NON-GRAPHITIC CARBON by GRAPHITIZATION HEAT TREATMENT. 

See carbon fibers, graphitizable carbon, graphitization heat treatment, synthetic graphite... 

Graphitizable carbon is a non-graphitic carbon which upon graphitization heat treatment converts into graphitic carbon. 

See carbon materials, diamond, graphite, graphitization, graphitization heat treatment... 

Graphitization heat treatment is a process of heat treatment of a non-graphitic carbon, industrially performed at temperatures in the range between 2500 and 3300 K, to achieve transformation into graphitic carbon. 

See graphite material, graphitization heat treatment, pyrolytic carbon... 

Sato S, Sato K, Inamura Y. A rationalization of the graphitizing heat treatment process of carbon. Carbon. 1975 13 309-16. 

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