Graphite powder is a kind of mineral powder, mainly composed of carbon, soft and dark gray; It is greasy and can pollute the paper. The hardness is 1-2, and the hardness can increase to 3-5 with the increase of impurities in the vertical direction. The specific gravity is 1.9~2.3. Under the condition of isolating oxygen, its melting point is above 3000 ℃, and it is one of the most temperature-resistant minerals. Under normal temperature, the chemical properties of graphite powder are relatively stable, insoluble in water, dilute acid, dilute alkali and organic solvent; The material has high temperature resistance and conductivity, and can be used as refractory, conductive and wear-resistant lubricating materials.
1. Used as refractory material: graphite and its products have the properties of high temperature resistance and high strength. They are mainly used to make graphite crucibles in the metallurgical industry. In steelmaking, graphite is often used as the protective agent for steel ingots and the lining of metallurgical furnaces.
2. Used as conductive material: used in the electrical industry to manufacture electrodes, brushes, carbon rods, carbon tubes, the positive pole of mercury positive current, graphite gaskets, telephone parts, and coating of television picture tubes.
3. As wear-resistant lubricating material: graphite is often used as lubricant in the mechanical industry. Lubricating oil can not be used at high speed, high temperature and high pressure, while graphite wear-resistant material can work without lubricating oil at high sliding speed at (I) 200~2000 ℃. Many equipment transporting corrosive media are widely made of graphite materials into piston cups, sealing rings and bearings. They do not need to add lubricating oil during operation. Graphite emulsion is also a good lubricant for many metal processing (wire drawing and pipe drawing).
Graphite has good chemical stability. Specially processed graphite has the characteristics of corrosion resistance, good thermal conductivity and low permeability. It is widely used to make heat exchangers, reaction tanks, condensers, combustion towers, absorption towers, coolers, heaters, filters and pump equipment. It is widely used in petrochemical, hydrometallurgy, acid and alkali production, synthetic fiber, paper and other industrial sectors, which can save a lot of metal materials.
Used as casting, foundry, molding and high-temperature metallurgical materials: Due to the small thermal expansion coefficient of graphite and its ability to withstand the changes of rapid cooling and heat, it can be used as a mold for glassware. After the use of graphite, the ferrous metal can obtain accurate casting size, high surface finish rate, and can be used without processing or slight processing, thus saving a lot of metal. For the production of cemented carbide and other powder metallurgy processes, graphite materials are usually used to make ceramic boats for pressing and sintering. The crystal growth crucible of monocrystalline silicon, regional refining container, bracket clamp, induction heater, etc. are all made of high-purity graphite. In addition, graphite can also be used as graphite insulation plate and base for vacuum smelting, high-temperature resistance furnace tube, rod, plate, lattice and other components.
Graphite can also prevent boiler scaling. Relevant unit tests show that adding a certain amount of graphite powder (about 4~5 grams per ton of water) to water can prevent boiler surface scaling. In addition, graphite coating on metal chimney, roof, bridge and pipeline can prevent corrosion and rust.
Graphite can be used as pencil lead, pigment and polishing agent. After special processing, graphite can be made into various special materials for relevant industrial departments.
In addition, graphite is also a polishing agent and antirust agent for glass and paper in light industry, and an indispensable raw material for manufacturing pencils, ink, black paint, ink, artificial diamonds and diamonds. It is a good energy saving and environmental protection material, which has been used as automobile battery in the United States. With the development of modern science, technology and industry, the application field of graphite is still expanding. It has become an important raw material for new composite materials in the high-tech field and plays an important role in the national economy.
Folding national defense
Used in the atomic energy industry and national defense industry: graphite has good neutron moderator for use in atomic reactors, and uranium-graphite reactor is a kind of atomic reactor that is widely used. The decelerating material in the nuclear reactor used as power should have high melting point, stability and corrosion resistance. Graphite can fully meet the above requirements. The purity of graphite used as an atomic reactor is very high, and the impurity content should not exceed dozens of PPMs. In particular, the boron content should be less than 0.5PPM. In the national defense industry, graphite is also used to make nozzle of solid fuel rocket, nose cone of missile, parts of space navigation equipment, thermal insulation materials and anti-radiation materials.
Post time: Mar-15-2023