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Graphite Takes You Through Process of Producing High Purity Graphite Rods

The production of high-purity metal and semiconductor materials often use graphite crucible and graphite heaters, high purity graphite rods. In order to ensure that the metal and semiconductor materials produced to achieve the desired purity, reduce the amount of impurities, the use of high carbon content, impurities, high purity graphite. The original hand can industrial graphite, in addition to the total impurity content is low, the allowable content of boron in impurities there are special requirements.
General Graphite LU Products impurity content of about 0.3%, high purity graphite rods according to the use of different requirements under 0.05%, some requirements under 0.01%.
The production of high-purity graphite, starting from the raw materials should be strictly control of impurities, the selection of low ash raw materials, and in the production process as far as possible to prevent increased impurities. However, reducing impurities to the extent required is mainly in the graphitization process. Graphitization is done at high temperatures, and many of the impurity elements will decompose and evaporate at such high temperatures.
The higher the graphitization temperature, the more impurities are discharged and the higher the purity of the graphite products produced. In the production of general graphite products, the furnace core temperature of about 2300T, residual impurities content of 0.1% ~ 0.3% or so. If the maximum temperature of the furnace core is increased to 2500~3000t:, the residual impurity content will be greatly reduced. The method to improve the furnace temperature of graphitization furnaces is to reduce the furnace core section (i.e. to decrease the furnace load) to increase the current density of the furnace core and increase the power consumption per ton of products.
The furnace bottom material and the heat preservation material will be changed to carbon black, also can achieve the goal of raising the temperature. However, because of the high production cost of this method, it is less used in actual production. In the production of high-purity graphite products, resistance and insulation are usually used in low gray oil coke.
Even if the temperature of the graphite is raised to 2800T, some impurities are difficult to remove. Because these impurities produce refractory carbides or dissolve in graphite crystals at high temperatures. In addition to the above reasons, the use of reduced furnace core and improve the current density, such as improving the furnace temperature, the graphite furnace production will be reduced, the power consumption increased.
Therefore, the regulation in the production of high-purity graphite rods are used in the process of graphitization through the "purification of Gas" method, purifying gases such as chlorine gas, two chlorofluorocarbons (Freon) can make the graphite contains difficult to remove impurities in the formation of easy decomposition and easy to gasification of chloride or fluoride. Usually in the graphitization furnace temperature reached 1800T after the purification of gas.