Semigraphite

Coal electrodes Coke electrodes Semigraphite electrodes High purity electrodes... 

Various forms of carbon, semigraphite, and graphite materials have found wide apphcation ia the metals iadustry, particularly ia connection with the productioa of iroa, alumiaum, and ferroalloys. Carbon has been used as a refractory material siace 1850, though full commercial acceptance and subsequent rapid iacrease ia use has occurred only siace 1945. 

With regard to purity, carbon blacks consist of almost 100% pure carbon, with a semigraphitic structure, but the particle smfaces have oxygen-rich reactive functional groups such as phenolic, ketone, quinone, lactone, hydroxyl and carboxyl. Their concentration is proportional to the volatile content , which is a positive factor in UV stabilisation. 

Li, J., Fang, Z., Lai, Y. etal. (2009) Electrolysis expansion performance of semigraphitic cathode in [KjAlFg/NajAlFg]-AlFj-AljOj bath system. J. Cent. South Univ. Technol., 16, 422-428. 

In carbon materials, almost aU the porosity is open. The number of closed pores is small, especially in graphitic materials. The exception is the closed porosity in anthracite grains, which are used for the production of semigraphitic carbon cathode materials. In semigraphitic carbon blocks, there is a certain portion (<5 %) of closed pores. 

Electrically calcined anthracite is considered to be a more advanced raw material for semigraphitic blocks compared with gas-calcined anthracite, because it gives a lower electrical resistivity of carbon cathode blocks and a very small (but detected)... 

The graphitization promotes stable electrical characteristics of semigraphitic... 

So the graphitization of anthracitic or semigraphitic blocks is followed by the increase in the pore volume, whereas the pores are filled in with bath. The process of graphitization may also be followed by the fracture of coke bridges between the grains of graphite and anthracite, which in a pessimistic variant may cause cracking. 

Erosion increases the wear, and the combined mechanism of chemical wear takes place. Once at the smelter, there is a decision to modernize and to install graphitic or graphitized blocks instead of semigraphitic, and the increased wear takes place. Anthracite is sufficiently harder than graphite. Yet there is no direct proportionality between the wear rates and the graphite content in the blocks [87]. 

The words carbon and graphite are often used interchangeably in the literature, but the two are not synonymous. Additionally, the words semigraphite and semigraphitic are also similarly misused. The following describes the composition, processing, and major characteristics of these various carbonaceous materials. 

The proprietary hot press method of manufacturing brick can also be used to make true semigraphite products, utilizing graphite particles combined with carbon binder and other proprietary ingredients. The process is as described... 

The resultant semigraphitized carbon, in which both particles and binder are semigraphitized, provides a material with higher thermal conductivity and chemical attack (from alkali or oxidation) resistance than either carbon or semigraphite materials. This is because alkalis and zinc attack the binder material first and the semigraphitized binder is more resistant to attack than the carbon binder of semigraphite. 

Table 3 provides a limited list of various semigraphite and semigraphitized materials and their properties. 

Table 3 Typical Semigraphite and Semigraphitized Carbon Refractory Material Properties... 

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