Vitreous carbon types

The first coupling reaction of this type studied utilized a 3-methoxyphenyl ring as the aryl coupling partner (Scheme 36) [47a, c]. The reaction employed constant current electrolysis conditions and a reticulated vitreous carbon anode (RVC). A good yield of cyclized material was obtained. However, the reaction was plagued by the formation of secondary products derived from over-oxidation (35 and 36) of the initially formed cyclization products (33 and 34). The amount of over-oxidized material could be greatly reduced with the use of controlled potential electrolysis conditions. 

Figure 9.10 Assembly of sandwich-type optically transparent electrochemical cell for extended x-ray absorbance fine structure (EXAFS) spectroelectrochemistry. Cell body is of MACOR working electrode is reticulated vitreous carbon (RVC). [From Ref. 64, with permission.]...

Amorphous carbon is a general term that covers non-crystalline forms of carbon such as coal, coke, charcoal, carbon black (soot), activated carbon, vitreous carbon, glassy carbon, carbon fiber, carbon nanotubes, and carbon onions, which are important materials and widely used in industry. The arrangements of the carbon atoms in amorphous carbon are different from those in diamond, graphite, and fullerenes, but the bond types of carbon atoms are the same as in these three crystalline allotropes. Most forms of amorphous carbon consist of graphite scraps in irregularly packing. 

With regard to electrode material, it can be seen (Tables 4 and 5) that cathodic limits on mercury are displaced by a few tenths of a volt to more negative potentials than on platinum. On the anodic side, the number of practically useful electrode materials is limited to noble metals and different types of carbon one case (anodic limit of pyridine nos. 35 and 36) shows that the anodic limit is lower on graphite than on platinum, and this seems to be a general trend for the comparison of carbon based anode materials, except possibly for vitreous carbon (Table 5) and bright (smooth, polished or shiny) platinum. 

Carbon—Graphite electrodes are often used, but they are less stable toward corrosion/phys-ical degradation than platinum. Graphite is available in many forms, including woven cloths, reticulated foam, and glassy (vitreous) carbon rods and plates. Organic products at different types of graphite anodes may differ considerably [60]. 

Two types of FP traps have been installed in JOYO. One is a cesium trap installed in the primary coolant sodium purification system to capture cesium released from failed fuels. An open pore, foam-like glassy carbon that consists of thin struts of Reticulated Vitreous Carbon (RVC) is used as a material for collecting cesium. The capacity of this trap is designed to be 7.4E+12 Bq. The other trap is a Cover Gas Clean-up System (CGCS) to collect and store the noble fission gas released from failed fuels. Although it is planned that only one failed fuel pin will be in the core at any time, the CGCS is designed to handle the releases of up to twelve failed fuel pins. 

The effectiveness of electrocatalytic hydrogenation depends upon the nature of the support and the metal of the electrodes. For that reason, a variety of materials have been developed, including Raney Ni/Ni, Raney Ni/Hg pool, Pt/Pt, Pt/C, Rh/C [62], Pt/Pt, and Pt/C with different concentrations of Pt [63] and different types of composite materials incorporated in reticulated vitreous carbon like fractal Ni, crystalline Ni B, and metallic nanoaggregates deposited on nonconductive... 

Vitreous carbon is obtained by the carbonization of organic polymers, commonly known as plastics. The types of polymers and the carbonization process and mechanism are reviewed in broad terms in Ch. 3, Sec. 2. 

Vitreous carbon can be produced in three basic types which have essentially the same microstructure, but different macrostructures solid (or monolithic), foam (or reticulated), and spheres (or particles). Each type is reviewed in the next three sections. 

Electrodes. Its chemical inertness, its wide range of usable potential (1.2 to -1.0 V vs. SCE) and the hydrodynamic and structural advantages of its open-pore foam structure make vitreous carbon foam an attractive material for electrodes for lithium-ion and other types of batteries, with many potential applications in electrochemistry.[ l[ ll ]... 

The situation is somewhat different with solid electrodes several materials are used here such as platinum, gold, as well as different types of carbon materials, e.g., glassy (vitreous) carbon etc. All these solid electrodes are particularly convenient in... 

One of the newest types of porous, three-dimensional materials to receive attention is reticulated (foam) metal (e,g. Ni, stainless steel, Cu) or carbon, e.g. reticulated vitreous carbon (RVC). The open-cell (alveoli like) porous structure of these materials confers a range of interesting properties ... 

Carbon presents a great variety of forms amorphous carbon, graphite, diamond, vitreous carbon and pyrolitic carbon. Some of them display the most excellent properties of biocompatibility, chemical inertia and thromboresistance that any other bioceramic. On the other hand, another advantage of these materials is that their physical characteristics are next to those of the bone [40]. Thus, their densities, according to the type carbon, change between 1.5 - 2.2 g/cm, and their elastic modules between 4-35 GPa. In spite of all the mentioned... 

---