Industry News

- April 29, 2021


Graphitization of calcined products is the main process of producing artificial graphite products. The so-called graphitization is a high-temperature heat treatment process in which non-graphitic carbon, which is thermodynamically unstable, is transformed into graphitic carbon through thermal activation.

Graphitization process usually uses low ash graphitizable carbon, such as petroleum coke, pitch coke and other roasted products as graphitization raw materials. The main difference in structure between calcined products and graphite products lies in the degree of order in the arrangement of their carbon atoms. Graphitization is to achieve the following purposes by changing the order;

(1) Improve the electrical conductivity and thermal conductivity of the product;

(2) Improve the thermal shock resistance and chemical stability of products;

(3) Improve the lubricity of products;

(4) Discharge impurities and improve the purity of products.

The formation of cracks in the blank during the graphitization process

The destruction of the electrode (or other products) blank during the graphitization process is the formation of cracks on the surface and inside of the blank. It can also be divided into: transverse cracks (that is, cracks on the surface of the product along the circumferential direction), longitudinal cracks (cracks along the length of the product), star cracks (that is, star-shaped expansion from one point to several directions). From a macro perspective, the reasons are:

(1) The products in the furnace are arranged unevenly, and the resistance material is unevenly filled, and there is even a phenomenon of resistance material "shed material". After the power is turned on, the uneven current everywhere causes a large temperature difference.

(2) When using graphitized metallurgical coke and ordinary metallurgical coke mixed resistance material, the two coke must be mixed evenly. If the mixing is uneven, the temperature of the furnace core cannot be uniform, and a large number of cracked waste products are easily produced.

(3) When the power is turned on, the starting power and rising power are too large, and the temperature of the furnace core rises too fast. When ordinary metallurgical coke is used as the resistance material to charge the furnace, the rapid rise of the power will easily cause cracks in large-size products and fine-structure graphite products.

(4) Sometimes the cracks produced are a large number of longitudinal and star-shaped cracks. It is generally believed that the quality of the previous processes (such as calcination) fluctuates and is concentratedly exposed during the graphitization process.