High-purity graphitization principle

During the graphitization heat treatment, the process of chemically removing impurity elements and their compounds in the product to obtain high-purity graphite products is called high-purity graphitization. At ordinary graphitization temperature, some high-boiling impurity compounds in graphite materials are difficult to gasify and escape. For example, the boiling point of boron carbide is 3500 °C, the boiling point of vanadium carbide is 3900 °C, and the boiling point of titanium is 3287 °C. Impurities are difficult. However, most metal halides have very low melting and boiling points. Therefore, fluorination or chlorination chemical reactions can be used to convert these high-boiling impurity compounds into metal halides that are easily decomposed and escaped, so that low impurity content can be prepared. of high-purity graphite material.

During graphitization, chlorine gas or freon is introduced into the furnace as purification gas, which decomposes into element fluorine and chlorine at high temperature, and these chemically active halogen elements react with various impurity elements and their compounds in graphite products , combined with the formation of halides with low melting and boiling points, and gasification and escape.