Graphitization is the process of heating the baked carbon blank to ultra-high temperature, usually above 2500℃, in an inert atmosphere to transform the disordered carbon into a graphite crystal structure. During the graphitization, the carbon atoms rearrange and form the layered graphite structure, and the lattice defects are reduced. The graphitization improves the thermal conductivity, electrical conductivity and high-temperature stability of the carbon material. The degree of graphitization determines the quality and performance of the final graphite product. The graphitization is the most energy-intensive process in the graphite production.
There are two main types of graphitization furnaces: the Acheson furnace and the internal series furnace. The Acheson furnace is a traditional resistance furnace, in which the carbon blanks are packed with a resistance material and heated by the electrical current. The internal series furnace is a more advanced type, in which the carbon blanks are connected in series and heated by the electrical current passing through them directly. The internal series furnace has a higher energy efficiency and a more uniform temperature distribution. The selection of the furnace type depends on the product type and the production scale.
The process parameters of graphitization include the maximum temperature, the heating rate, the holding time and the atmosphere. The maximum temperature determines the graphitization degree. The heating rate should be controlled to avoid the thermal stress and the cracking of the blanks. The holding time at the maximum temperature ensures the complete graphitization. The atmosphere in the furnace must be inert to prevent the oxidation of the carbon material. The control of these parameters is important for the quality of the graphitized product.
The temperature distribution in the graphitization furnace affects the uniformity of the graphitization. The non-uniform temperature distribution results in inconsistent graphitization degree and properties of the products. The design of the furnace and the packing of the blanks affect the temperature distribution. The computer-controlled temperature management helps to optimize the heating curve and ensure the uniform temperature. The monitoring of the temperature during the graphitization is important for the process control.
The quality inspection after graphitization includes the measurement of the graphitization degree, the resistivity, the density and the visual inspection. The graphitization degree is measured by X-ray diffraction analysis. The resistivity is a direct indicator of the graphitization degree, and the lower resistivity indicates a higher graphitization degree. The density and the mechanical properties are also tested. The visual inspection detects the surface defects and the deformation. The qualified graphitized products are delivered to the next process or the finished product inspection.
The stable operation of the graphitization furnace is important for the production efficiency and the product quality. The maintenance of the furnace, including the inspection of the electrical system and the refractory lining, ensures the reliable operation. The energy consumption of the graphitization is a major cost factor, and the optimization of the furnace operation improves the energy efficiency. The recovery of the heat and the by-products improves the overall efficiency of the production.
Jincheng Graphite uses advanced graphitization equipment and computer-controlled temperature management to ensure the complete graphitization of its products. The company optimizes the graphitization heating curve and controls the furnace atmosphere strictly. The graphitization degree and the physical properties of each batch of products are tested. The stable graphitization process ensures the consistent quality of the graphite products. Jincheng Graphite provides graphite products with stable quality for high-temperature furnace, chemical equipment, EDM and other applications.
Looking forward, the development of the graphitization technology focuses on improving the energy efficiency and the temperature uniformity. The application of the continuous graphitization equipment and the intelligent control system improves the production efficiency and the product quality. Jincheng Graphite will continue to improve its graphitization technology and provide high-quality graphite products for customers.
