Graphite is soft, black and gray; greasy, polluting paper. The hardness is 1~2, and the hardness increases to 3~5 with the increase of impurity in the vertical direction. The specific gravity is 1.9 ~ 2.3. The specific surface area is concentrated at 1-20m2/g, and the melting point is above 3000 degrees under the condition of oxygen isolation. It is one of the most temperature resistant minerals. It can conduct electricity and conduct heat.
According to these characteristics, graphite products are widely used in the following industry areas:
1, refractory material: graphite and its products have the properties of high temperature resistance, high strength, in the metallurgical industry is mainly used to manufacture steel commonly used in graphite crucible, graphite as the protective agent of steel ingot, metallurgical furnace lining.
2, conductive material: used for manufacturing the electrode, carbon nanotubes, carbon brush, and the positive electrode of the mercury rectifier in the electrical industry, graphite gasket, telephone parts, TV tube coating etc..
3, as wear-resistant lubrication material: graphite is often used as lubricant in the machinery industry. Lubricants can not be used in high speed, high temperature, high pressure conditions, and graphite wear-resistant materials can be at 200~2000 C temperature in a high sliding speed, without lubricating oil work. Many devices that transport corrosive media are made of graphite materials, piston cups, seals and bearings. They do not need to be lubricated when they are running. Graphite is many metal processing (drawing, drawing) the good lubricant.
4. Graphite has good chemical stability. After special processing of graphite, with corrosion resistance, good thermal conductivity, low permeability, is widely used in the manufacturing of the heat exchanger, the reaction tank, condenser, combustion tower, absorption tower, cooler, heater, filter and pump equipment. Widely used in petrochemical, hydrometallurgy, acid and alkali production, synthetic fiber, papermaking and other industrial sectors, can save a lot of metal materials.
5, casting, casting, molding and high-temperature metallurgical material: Graphite due to thermal expansion coefficient is small, and the capability of cold and hot change, can be used as a mold of the glass, the use of graphite after black metal castings get precise size, smooth surface, high rate of finished products, can be used without processing or a processing. So we can save a lot of metal. The powder metallurgy process, such as cemented carbide, is usually made of graphite material and used as a porcelain boat for pressing and sintering. The crystal growth of monocrystalline silicon, crucible, refining vessel, bracket jig, induction heater and so on are all processed by high purity graphite. In addition, graphite can be used as vacuum melting graphite insulation board and base, high temperature resistance furnace tube, rod, plate, lattice and other components.
6, for the atomic energy industry and the national defense industry: graphite has a good neutron reducer used in atomic reactors, uranium graphite reactor is one of the more widely used atomic reactor. As a power plant, the deceleration material in the atomic energy reactor should have high melting point, stability and corrosion resistance, and graphite can meet the above requirements. As an atomic reactor, the purity of graphite is very high, and the impurity content should not exceed tens of PPM. In particular, boron content should be less than 0.5PPM. In the defense industry, graphite is also used to make nozzles for solid rocket rockets, nose cones for missiles, parts for aerospace equipment, thermal insulation materials and radiation protection materials.
7, graphite can prevent boiler scaling, the unit test shows that adding a certain amount of graphite powder in water (4~5 grams per ton of water) can prevent boiler surface scaling. In addition, graphite can be applied to metal chimneys, roofs, bridges and pipelines to prevent corrosion and rust.
8. Graphite can be used as pencil core, pigment and polishing agent. After special processing, graphite can be made into various special materials for industrial departments.
10. Modifying agent to improve the wear and corrosion resistance of rubber.