Graphite is divided into two types, one is natural graphite; the other is artificial graphite. Although with the improvement of manufacturing technology, the function of artificial graphite is no less than that of natural graphite in many cases, but in some fields, natural graphite has always maintained a unique advantage.
Among natural graphite resources, flake graphite (crystalline graphite) has small reserves and high value. It has good electrical and thermal conductivity, lubricity and oxidation resistance. It is widely used in metallurgy, machinery, chemical industry, refractory materials, aerospace and other industries. , Is one of the non-metallic materials indispensable for the development of today's high-tech.
Natural flake graphite peeling
The flake graphite structure is flake-like and has good surface properties, which makes it have good natural floatability and is one of the most floatable minerals in nature. According to the size of the flakes, graphite flakes can be divided into large flake graphite (with a particle size of 0.3mm, 0.18mm, 0.15mm) and fine flake graphite (with a particle size of less than 0.15mm). However, in comparison, large flake graphite has more advantages in the market and application, and the price of large flake graphite of the same grade is much higher than that of fine flake graphite.
Closely related to graphite applications is the purity of graphite. It can be said that technical purification is the prerequisite for the processing of graphite raw materials into graphite materials. Afterwards, according to the field of application, graphite needs to be reprocessed in terms of particle size, morphology or performance. Specific purification operations.
1. Graphene
Graphene is a carbon material with a very high specific surface area and wide application potential. It has significant advantages over other products in terms of specific capacity, cost, and lifespan. Its raw materials are mainly related to product types and preparation methods.
For example, the raw materials of mechanical exfoliation method, epitaxial growth method, and graphite oxide reduction method are all natural flake (crystalline) graphite, among which large flake graphite is more conducive to the formation of graphene; while the raw material of graphene film prepared by vapor deposition method contains Carbon gas has nothing to do with graphite.
2. Expanded graphite
As a new type of functional carbon material, expanded graphite (EG) is a loose, porous, worm-like substance obtained from natural graphite flakes through intercalation, washing, drying, and high temperature expansion. Large flake graphite and fine particles must be used for production Grades cannot be used or are difficult to use.
In addition to the excellent properties of natural graphite, such as resistance to cold and heat, corrosion resistance, and self-lubrication, EG also has softness, compression resilience, adsorption, ecological environment coordination, biocompatibility, and radiation resistance that natural graphite does not have. And other characteristics. It has a wide range of uses. It can be used as fireproof fillers, medical dressings, and can also be processed into flexible graphite for sealing materials.
3. Refractory materials
Flake graphite itself has excellent thermal shock resistance and slag erosion resistance. After being made into products, it also has the properties of high temperature resistance and high strength. It is widely used in advanced refractory materials and coatings in the metallurgical industry, such as in steelmaking. Protective agent for steel ingots, lining of metallurgical furnaces, magnesia carbon bricks, crucibles, etc. However, it should be noted that it is best to use large flake graphite when manufacturing crucibles.
4. Lubricating material
The good lubricity of graphite materials comes from the graphite crystal structure. Among them, the lubricity of large flake graphite is better than that of fine flake graphite. The larger the graphite flakes, the lower the friction coefficient and the better the lubricity. Flake graphite is often used as a lubricant in the machinery industry. The graphite milk produced by deep processing is a good lubricant for many metal processing (wire drawing, pipe drawing).
In addition, lubricating oil will be greatly reduced when used under high-speed, high-temperature, and high-pressure conditions, while graphite wear-resistant materials can work without lubricating oil at temperatures of 200 to 2000℃ and high speeds. In many equipment that transports corrosive media, graphite materials are also widely used to make piston cups, seals and bearings, so there is no need to add lubricating oil during operation.
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