Graphitization is a high-temperature heat treatment process in which carbon products are heated to above 2300 ℃ in the protective medium in a high temperature electric furnace to transform amorphous disordered structure carbon into three-dimensional ordered stone inky structure.
Graphitization of graphite electrode is carried out at a high temperature of 2300-3000 ℃. Therefore, in industry, it can only be realized by means of electric heating, that is, the current passes through the heated roasted products directly. The roasted products in the furnace are not only the conductor of high temperature generated by the current, but also the objects heated to high temperature.
• At present, widely used furnace types are Acheson graphitization furnace and internal heat series (LWG) furnace. The former has large output, large temperature difference and high power consumption, while the latter has short heating time, low power consumption and uniform resistivity, but it is difficult to install the joint.
• The graphitization process is controlled by determining the electrical power curve corresponding to the temperature rise through temperature measurement. The electrification time is 50-80 hours for Acheson furnace and 9-15 hours for LWG furnace.
• Graphitization consumes a lot of power, generally 3200-4800kwh, and the process cost accounts for about 20-35% of the total production cost
• Inspection of graphitized products: appearance percussion, resistivity test
Purpose and function of graphitization:
• Improve the electrical conductivity and thermal conductivity of carbon materials (the resistivity decreases 4-5 times, the thermal conductivity increases about 10 times);
• Improve thermal shock resistance and chemical stability of carbon materials (linear expansion coefficient reduced by 50-80%);
•Make the carbon material lubricity and wear resistance;
•discharge impurities, improve the purity of carbon materials (the ash content of products from 0.5-0.8% to 0.3% or so).