The difference and connection between natural graphite and artificial graphite

In view of the fact that the artificial graphite in the narrow sense is usually prepared from natural graphite as raw material, this article only analyzes and discusses the difference and connection between natural graphite and artificial graphite in the narrow sense.

Crystal structure

The crystal development of natural graphite is relatively complete, the graphitization degree of natural flake graphite is usually above 98%, and the graphitization degree of natural microcrystalline graphite is usually below 93%.

The degree of crystal development of artificial graphite depends on the raw material and the heat treatment temperature. Generally speaking, the higher the heat treatment temperature, the higher the degree of graphitization. At present, the degree of graphitization of artificial graphite produced in industry is usually less than 90%.

Organizational structure

Natural flake graphite is a single crystal with a relatively simple structure, with only crystallographic defects (point defects, dislocations, stacking faults, etc.), and macroscopically showing anisotropic structural characteristics. The grains of natural microcrystalline graphite are small, the grains are disorderly arranged, and there are pores after the impurities are removed, showing the isotropic structural characteristics on the macroscopic level.

Artificial graphite can be regarded as a kind of multiphase material, including the graphite phase transformed by carbonaceous particles such as petroleum coke or asphalt coke, the graphite phase transformed by coal pitch binder coated around the particles, and the pores formed by particle accumulation or coal pitch binder after heat treatment.

Physical form

Natural graphite usually exists in the form of powder and can be used alone, but it is usually used in combination with other materials.

There are many forms of artificial graphite, including powder, fiber and block, while artificial graphite in the narrow sense is usually block, which needs to be processed into a certain shape when used.

Physical and chemical properties

Natural graphite and artificial graphite have commonness, also exist the difference on the performance. For example, natural graphite and artificial graphite are good conductors of heat and electricity, but for the same purity and particle size of graphite powder, natural flake graphite heat transfer performance and conductivity is the best, natural microcrystalline stone ink second, artificial graphite lowest.

Graphite has good lubricity and certain plasticity, natural flake graphite crystal development is more perfect, friction coefficient is small, the best lubricity, the highest plasticity, and dense crystalline graphite and cryptocrystalline graphite, artificial graphite is poor.

Application field

Graphite has many excellent properties, so it is widely used in metallurgy, machinery, electrical, chemical, textile, national defense and other industrial sectors. The application fields of natural graphite and artificial graphite both overlap and differ.

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 of natural graphite are difficult to use in steelmaking electric furnaces with harsh operating conditions.

In the machinery industry, graphite materials are usually used as wear-resistant and lubricating materials. Natural flake graphite has good lubricity and is often used as an additive for lubricating oils.

The equipment for conveying corrosive media widely uses piston rings, sealing rings and bearings made of artificial graphite, and does not need to add lubricating oil during operation.

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

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

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