Baked carbon

Self-baked carbon electrodes are those whose shapes are formed in situ (33). The carbonaceous mixture is placed into a hoUow tube-shaped metal casing. The upper end receives the unbaked mixture as a soHd block, small particles, or warm plastic paste. The casing contains inwardly-projecting longitudinal perforated fins that become surrounded by baked carbon as the casing is incrementally moved downward and through the contact plates. Casing and carbon are consumed in this furnace. 

Because of their low thermal conductivity, high temperature capability, low cost, and neutron tolerance, carbon materials make ideal thermal insulators in nuclear reactor environments. For example, the HTTR currently under construction in Japan, uses a baked carbon material (Sigri, Germany grade ASR-ORB) as a thermal insulator layer at the base of the core, between the lower plenum graphite blocks and the bottom floor graphite blocks [47]. 

The reaction conditions, normally applied, are those described in chap. 2 for the radical pathway. These are a platinum anode, high current densities, no additives and a slightly acidic medium. However, the dimerizations shown in Table 2, No. 2, also gave in some cases good yields at a carbon anode in acetonitrile-water [52] or at a baked carbon anode in methanol [48]. With propionic and butyric acid an unusually high portion of alkene is formed at the cost of the dimer. 

Self-association, of surfactants, 22 725 Self-baking carbon electrodes, 12 752, 757-758... 

Solvent Pt Vitreous carbon Baked carbon Graphite ... 

Solvent/anode material Graphite Vitreous carbon Baked carbon Platinum... 

The most important objective for anode filler aggregate sizing is to obtain a high vibrated aggregate bulk density (23). For prebake anodes, maximum aggregate bulk density is required to achieve maximum baked carbon density. For Soderberg anodes, this requirement is somewhat modified by paste rheological requirements... 

Anode porosity is important because it affects the extent of oxidant-accessible surface. This surface is influenced both by coke microstructure and the fabrication process for converting the raw materials into baked carbon. The prime requirement for good anode carbon is minimum oxidant-accessible surface. It is also desirable that this surface have a low, uniform specific reactivity. Anode surface with pores having diameters in the 1-10 micron range are accessible to oxidation unless blocked in some manner. Submicron porosity, such as that produced by thermal desulfurization of coke, is oxidant diffusion-limited and will not affect carbon consumption significantly. Increasing anode carbon density will usually increase anode performance because the oxidant-accessible surface is reduced. 

As anode material, smooth platinum, as foil or net, is most widely used. In nonaqueous solvents, additionally, platinized titanium, gold, hard graphite and ruthenium dioxide on titanium have been employed. To keep the amount of the costly platinum low, the foils have been glued to a graphite support. With vitreous or baked carbon in protic solvents (methanol, ethanol, water) dimer yields nearly comparable to those at platinum have been obtained. ... 

Thonstadt, J. (1973). Double-layer capacity of graphite in cryohte-alumnina melts and surface area changes by electrolyte consumption of graphite and baked carbon. 

D 6558 (2000) Standard Test Method for Determination of TGA CO2 Reactivity of Baked Carbon Anodes and Cathode Blocks... 

Self-setting (phenolic urethane no bake) Carbon oxides Nitrogen oxides Monoisocyanates Formaldehyde Phenol, cresols and xylenols Aromatics (inc. polycyclics) Anilines Naphthalenes Armnonia ... 

The carbonized material is often called amorphous or baked carbon . It is without long-range crystalline order and the deviation of the interatomic distances of the carbon atoms (from the perfect graphite crystal) is greater than 5% in both the basal plane ab directions) and between planes (c direction), as determined by x-ray diffraction. 

Electrodes for Aluminum Production. Aluminum is processed electrolytically and the production of the necessary electrodes is the second-largest application of molded greiphite (see Table 5.11 above) The anodes are similar to those used in electric-arc steel production and are also manufactured from petroleum-coke filler and coal-tar pitch. The aluminum collects at the cathodes which are large blocks lining the electrolytic cell. These cathodes were originally made of baked carbon based on anthracite coal but, in recent years, have been upgraded and are now made of molded graphite from petroleum coke. 

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