In view of the fact that the above-mentioned natural gr […]
In view of the fact that the above-mentioned natural graphite as raw material is usually narrow artificial graphite, only the difference and relationship between natural graphite and narrow artificial graphite are analyzed and discussed.
1. Crystal structure
Natural graphite: The crystal development is relatively complete, the graphitization degree of flake graphite is more than 98%, and the graphitization degree of natural microcrystalline graphite is usually below 93%.
Artificial graphite: The degree of crystal growth depends on the raw material and 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%.
2. Organizational structure
Natural flake graphite: It is a single crystal with a simple structure and only crystallographic defects (such as point defects, dislocations, stacking faults, etc.), and it exhibits the characteristics of anisotropy macroscopically. Natural microcrystalline graphite has small crystal grains, and the crystal grains are disorderly arranged and there are pores after the impurities have been removed, and they are macroscopically isotropic.
Artificial graphite: can be regarded as a multi-phase material, including the graphite phase transformed by carbonaceous particles such as petroleum coke or pitch coke, the graphite phase transformed by the coal pitch binder coating around the particles, particle accumulation or coal pitch stick The pores formed by the heat treatment of the binder.
3. Physical form
Natural graphite: usually exists in powder form and can be used alone, but it is usually used after being compounded with other materials.
Artificial graphite: There are many forms, including powder, fibrous and block. The narrow artificial graphite is usually block and needs to be processed into a certain shape when used.
4. Physical and chemical properties
In terms of physical and chemical properties, natural graphite and artificial graphite have both commonalities and differences in performance. For example, natural graphite and artificial graphite are both 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 performance and electrical conductivity, followed by natural microcrystalline graphite, and artificial graphite lowest. Graphite has good lubricity and certain plasticity. Natural flake graphite has better crystal development, lower friction coefficient, best lubricity, and highest plasticity, followed by dense crystalline graphite and cryptocrystalline graphite, artificial graphite Poor.