Solid Carbon Materials

Solid carbon materials are available in a variety of crystallographic forms, typically classified as diamond, graphite, and amorphous carbon. More recently another structure of carbon was identified—namely the fullerenes which resemble a soccer ball... 

The carbonization of natural or industrial hydrocarbon mixtures annually produces about 2.2 billion tons of solid carbon which, depending on the final heat treatment temperature, is called coke or graphite. A wide range of premium carbons that are not based directly on coal, produced by plastic phase pyrolysis of fusible or liquid isotropic hydrocarbons, constitute about one percent (22 million t/a) of the total solid carbon material produced included are ... 

Pure decarbonization is not relevant for hydrocarbon pyrolysis, but may be of interest for high temperature treatment of solid carbon material like coke. 

A difficulty of principle arises when using a solid electrolyte in direct carbon fuel cells. In fact, in fuel cells with a liquid electrolyte (solution or melt) the entire surface area of the carbon material is in contact with the electrolyte (is wetted by the electrolyte). In fuel cells with a solid electrolyte, to the contrary, the contact between the solid carbon material and the solid electrolyte is a mere point contact, and the working surface area is much smaller. 

Clearly, the requirement of a MAS rate well above the CSA frequency range is quite restrictive for values of A/csa above approximately 20 kHz. Although there are solid-state NMR probes capable of providing MAS rates of this magnitude (or even higher), they are quite expensive and rotor sizes are sometimes prohibitively small [27]. The commonly used NMR probes with rotor diameters down to 4 mm typically spin at no more than 18 kHz and are, thus, not quite appropriate for use in NMR spectrometers with Bq above approximately 9.4 T when C NMR experiments with solid carbon materials are intended (unless TOSS or related methods are employed). Also, as mentioned in Section 2.3.2, use of fast MAS rates can bring serious problems to the efficiency of the CP process and consequently to a quantitative analysis of carbon materials using this method [56]. 

Mechanism of Lubrication for Solid Carbon Materials in Vacuum to 10" Millimeters of Mercury, D.H. Buckley and R.L. Johnson, ASLE Trans.. 7(1) 91-100, 1964. 

Moreover, carbon support corrosion also results in thinning of the electrodes. The solid carbon material is oxidized to CO2 and a very thin layer is remaining in the MEA. This very thin layer is consisting of mily small amounts of carbon, but a very high platinum and binder concentration can be observed (Fig. 15.2). 

Carbon mix is a mixture of filler coke, for example grains and/or powders of solid carbon materials, and a carbonaceous binder and selected additives, prepared in heated mixers at temperatures in the range of 410K-445K as a preliminary step for the formation of shaped green bodies. 

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