Electrodes graphite

Graphite reacts with alkali metals, for example potassium, to form compounds which are non-stoichiometric but which all have limiting compositions (for example K C) in these, the alkaU metal atoms are intercalated between the layers of carbon atoms. In the preparation of fluorine by electrolysis of a molten fluoride with graphite electrodes the solid compound (CF) polycarbon fluoride is formed, with fluorine on each carbon atom, causing puckering of the rings. 

This experiment describes the use of coated graphite electrodes for the potentiometric monitoring of precipitation, acid-base, complexation, and redox titrations. 

Graphite, bulk Graphite cathodes Graphite electrodes... 

Electrodes. Because of the numerous different processes, there are many different types of electrodes in use (9), eg, prefabricated graphite, prefabricated carbon, self-baking, and composite electrodes (see Carbon). Graphite electrodes are used primarily in smaller furnaces or in sealed furnaces. Prebaked carbon electrodes, made in diameters of <152 cm or 76 by 61 cm rectangular, are used primarily in smelting furnaces where the process requkes them. However, self-baking electrodes are preferred because of thek lower cost. 

The electrolysis is conducted at 90—95°C and an anode current density of about 50 120 A/m when using lead alloy anodes and lead cathodes. Using graphite electrodes, the current density is from 70 100 A/m using titanium anodes and graphite cathodes, the current density is 50 80 A/m (82). 

Property Aluminum anode-grade coke Graphite electrode-grade needle coke... 

With the exception of carbon use in the manufacture of aluminum, the largest use of carbon and graphite is as electrodes in electric-arc furnaces. In general, the use of graphite electrodes is restricted to open-arc furnaces of the type used in steel production whereas, carbon electrodes are employed in submerged-arc furnaces used in phosphoms, ferroalloy, and calcium carbide. 

Graphite electrodes are consumed in the melting process. For iron and steel production, the average consumption is ca 2—5 kg/1, depending on the... 

Table 2. Typical Room Temperature Properties of Regular- and Premium-Grade Graphite Electrodes and Connecting Pins...

A variety of products are made in submerged-arc furnaces. Among them are various alloys and compounds. Each uses a particular type or grade of carbon electrode to hold production costs at the lowest possible level. Graphite electrodes could be and are used in some submerged-arc furnaces. Such a choice is the result of special conditions that warrant use of the more expensive graphite in Heu of carbon. 

Production of carbon electrodes is a capital-intensive business. Two suppHers dominate the prebaked market. Carbon paste producers are more numerous and tend to serve local markets. There is no international standard for the threaded joints on carbon electrodes. Manufacturers of straight pin carbon electrodes have followed the physical specifications adopted for graphite electrodes (37). Unified standards do not exist for pinless joints resulting in limited interchangeability among brands. Electrode diameters are offered in both English and metric sizes with no restrictions on new or unique diameters. 

Manufactured Graphite Electrodes, NEMA Standards Pubhcation No. CG-1, National Electrical Manufacturers Association, Washington, D.C., 1981 (Rev. 1985,1987). 

Dissohition of metal is avoided by selecting a resistant material such as Pt, Pt coated on Ti, or Pt on Nb. Base metals are sometimes used, as are graphite electrodes. 

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