Graphite can be divided into natural graphite and artificial graphite, which have similar structures and physical and chemical properties, but have significant differences in their uses.  

Classification and characteristics of graphite:

Natural graphite

     Natural graphite is formed by the long-term transformation of carbon rich organic compounds in high-temperature and high-pressure geological environments, and is a crystallization of nature. The process characteristics of natural graphite mainly depend on its crystalline form. Minerals with different crystal forms have different industrial values and uses. There are many types of natural graphite, and according to their different crystal forms, natural graphite is divided into three categories in industry: dense crystalline graphite, flake graphite, and cryptocrystalline graphite. There are two main types of graphite in China: flake graphite and cryptocrystalline graphite.

Artificial graphite

        Artificial graphite is similar to polycrystals in crystallography. There are many types of artificial graphite, and their production processes vary greatly. In a broad sense, all graphite materials obtained by carbonization of organic matter and graphitization and high-temperature treatment can be collectively referred to as artificial graphite, such as carbon (graphite) fiber, pyrolytic carbon (graphite), foam graphite, etc. Narrowly defined, artificial graphite usually refers to solid block materials made from low impurity carbonaceous materials (such as petroleum coke, asphalt coke, etc.) as aggregates and coal tar pitch as binders, through processes such as batching, mixing, molding, carbonization (known as roasting in industry), and graphitization, such as graphite electrodes, hot isostatic pressed graphite, etc.

The difference and connection between natural graphite and artificial graphite

       Given that natural graphite is usually used as raw material to prepare narrow artificial graphite, this article only analyzes and discusses the differences and connections between natural graphite and narrow artificial graphite.

Physical and chemical properties

       Natural graphite and artificial graphite have both similarities and performance differences. Both natural graphite and artificial graphite are good conductors of heat and electricity, but for graphite powders of the same purity and particle size, natural flake graphite has the best heat transfer and conductivity, followed by natural microcrystalline graphite, and artificial graphite has the lowest.

      Graphite has good lubricity and certain plasticity. Natural flake graphite has well-developed crystals, lower friction coefficient, the best lubricity, and the highest plasticity, followed by dense crystalline graphite and cryptocrystalline graphite, while artificial graphite is inferior.

Application area

      Graphite has many excellent properties and is therefore widely used in industrial sectors such as metallurgy, machinery, electrical engineering, chemical engineering, textiles, and national defense. The application fields of natural graphite and artificial graphite overlap and differ from each other.

      In the metallurgical industry, natural flake graphite can be used to produce refractory materials such as magnesia carbon bricks and aluminum carbon bricks due to its good oxidation resistance.

       Artificial graphite can be used as steelmaking electrodes, while electrodes made from natural graphite are difficult to use in steelmaking electric furnaces with harsh operating conditions.

       In the mechanical industry, graphite materials are commonly used as wear-resistant and lubricating materials. Natural flake graphite has good lubricity and is commonly used as an additive in lubricating oil.

       The equipment for transporting corrosive media widely uses piston rings, sealing rings, and bearings made of artificial graphite, which do not require the addition of lubricating oil during operation.

       Natural graphite and polymer resin composite materials can also be used in the above-mentioned fields, but their wear resistance is not as good as artificial graphite.

       Artificial graphite has the characteristics of corrosion resistance, good thermal conductivity, and low permeability, and is widely used in the chemical industry to make equipment such as heat exchangers, reaction tanks, absorption towers, and filters.

        Natural graphite and polymer resin composite materials can also be used in the above-mentioned fields, but their thermal conductivity and corrosion resistance are not as good as artificial graphite.

       Developing artificial graphite using natural graphite as raw material

       In fact, drawing on the preparation process of artificial graphite to develop new graphite products is no longer a new topic in the artificial graphite industry. There are many carbon graphite products prepared using natural graphite as the main raw material or auxiliary raw material according to the production process of artificial graphite, and some have even formed a large industry.

       Zinc manganese battery carbon rod: a zinc manganese battery (commonly known as dry battery) carbon rod produced from natural microcrystalline graphite and coal tar pitch as the main raw materials, through processes such as mixing, extrusion molding, calcination, machining, and wax immersion.

       Mainly utilizing the high conductivity and low cost of natural microcrystalline graphite, it does not require high ash content, but has strict requirements for impurity content such as iron and sulfur.

        Natural graphite electric brush: an electric motor electric brush produced mainly from natural flake graphite and coal tar pitch, through processes such as mixing, rolling, grinding, molding, roasting (graphitization treatment if necessary), and machining.

      Mainly utilizing the high conductivity and orientation characteristics of natural flake graphite, it is required to have low impurities such as iron and sulfur content and ash content not exceeding 2%. During machining, attention should be paid to the orientation of flake graphite.