Carbon graphite-like, conversion

The importance of adsorption for different carbon materials and, conversely, the contribution of each type of carbon to the field of adsorption is very different. This reflects the ivide variability in properties of solid carbons [1, 2], which makes their surface properties important in very different fields and for different reasons. Thus, graphite, due to its relatively simple structure, has often been used as a model material to simulate the adsorption of different molecules on its surface, or to carry out adsorption measurements on a well-controlled surface. Likewise, carbon blacks, particularly those thermally treated ( graphi-tized ), have often been used as reference nonporous adsorbents, as they only exhibit an external surface. The absence of open porosity and high chemical inertia are attributes that make glass-like carbon a material ffequendy used in... 

The model postulates that diffuse cloud grains are composed of cores of silicate (some large, 2000 A and some small 100 A) each with a mantle of amorphous carbon (typical thickness 50 A). Freshly deposited amorphous carbon contains much sp bonded carbon, i.e. is diamond-like this is the metastable form. Exposure to UV radiation promotes the conversion to the more stable graphite-like form (sp bonding predominates). In both types of amorphous carbon, however, no long range order exists. The time... 

Reports on man-made diamond obtained by HPHT synthesis were first published in 1955 by General Electric [4]. Usually, metals able to dissolve carbon under HPHT conditions are used as catalysts and increase growth rates. Diamond crystals of several millimeters in size can be obtained in this way, but usually small grains for abrasives are produced. Direct conversion of graphite to diamond without catalyst in HPHT apparatus is possible, but uneconomical for industrial application. Direct transformation can be done by the detonation method and produces nanosized powders of diamond and diamond-like carbon [5]. 

Petroleum- and coal-derived pitches are basic raw materials for the manufacture of carbon and graphite. It is not surprising, then, that pitch was considered as a promising material for melt spinning into fibers for later conversion into carbon fibers. Pitch contains more than 90% carbon, much more than rayon or PAM. It is a con lex mixture of aromatic hydrocarbon molecules of wide molecular weight distribution and, therefore, behaves like a glass in its ability to be drawn into a fiber. 

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