What are the main applications of graphite?
- Traditional applications
1) Refractory materials: Graphite and its products have the properties of high temperature resistance and high strength. It is mainly used in the metallurgical industry to make graphite crucibles. In steelmaking, graphite is often used as a protective agent for steel ingots and as a lining for metallurgical furnaces.
2) Conductive materials: used in the electrical industry to make electrodes, brushes, carbon rods, carbon tubes, positive electrodes of mercury positive current devices, graphite washers, telephone parts, coatings for television picture tubes, etc.
3) Wear-resistant lubricating material: Graphite is often used as a lubricant in the machinery industry. Lubricating oil can not be used under high-speed, high-temperature, and high-pressure conditions, while graphite wear-resistant materials can work at high sliding speeds at a temperature of 200 to 2000 ℃ without lubricating oil. Many equipment for transporting corrosive media widely use graphite materials to make piston cups, sealing rings and bearings, and they do not need to add lubricating oil during operation. Graphite emulsion is also a good lubricant for many metal processing (wire drawing, pipe drawing).
4) Graphite has good chemical stability. Specially processed graphite has the characteristics of corrosion resistance, good thermal conductivity, and low permeability. It is widely used in the production of heat exchangers, reaction tanks, condensers, combustion towers, absorption towers, coolers, heaters, filters, Pump equipment. It is widely used in petrochemical industry, hydrometallurgy, acid-base production, synthetic fiber, papermaking and other industrial sectors, which can save a lot of metal materials.
5) Casting, sand foundry, die and high-temperature metallurgical materials: due to the small thermal expansion coefficient of graphite and the ability to withstand rapid changes in cold and heat, it can be used as a glass mold. After graphite is used, ferrous metals can be used to obtain castings with precise dimensions and a high surface smooth and finished product rate. , Can be used without processing or a little processing, thus saving a lot of metal. The production of cemented carbide and other powder metallurgy processes usually use graphite materials to make porcelain boats for compression molds and sintering. Single crystal silicon crystal growth crucibles, regional refining vessels, support fixtures, induction heaters, etc. are all made of high-purity graphite. In addition, graphite can also be used for vacuum smelting graphite heat insulation boards and bases, high-temperature resistance furnace tubes, rods, plates, grid sheds and other components.
6) Used in the atomic energy industry and national defense industry: Graphite has a good neutron moderator used in atomic reactors. Uranium-graphite reactor is a kind of atomic reactor that is widely used. The deceleration material in the nuclear reactor used as power should have high melting point, stability, and corrosion resistance. Graphite can fully meet the above requirements. As the graphite used in atomic reactors, the purity requirements are very high, and the impurity content should not exceed dozens of PPM, especially the boron content should be less than 0.5 PPM. In the defense industry, graphite is also used to make solid fuel rocket nozzles, missile nose cones, parts of aerospace equipment, heat insulation materials and radiation protection materials.
7) Graphite can also prevent boiler fouling. Tests by related units have shown that adding a certain amount of graphite powder (approximately 4 to 5 grams per ton of water) can prevent boiler surface fouling. In addition, graphite coating on metal chimneys, roofs, bridges, and pipes can prevent corrosion and rust.
8) Graphite can be used as pencil lead, pigment and polishing agent. After graphite is specially processed, various special materials can be made for use in relevant industrial sectors.
- New applications
1) Flexible graphite products. The flexible graphite sealing material solves the leakage problem of the atomic energy valve. In addition to the characteristics of natural graphite, this product also has special flexibility and elasticity, making it an ideal sealing material. It is widely used in petrochemical, atomic energy and other industrial fields.
2) Graphite is also a polishing agent and anti-rust agent for glass and papermaking in light industry, and is an indispensable raw material for the manufacture of pencils, ink, black paint, ink, synthetic diamonds, and diamonds.
With the development of modern science and 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.