The 21st century is the era of black gold, and the use of graphite products is much higher than we expected. So what are the uses of graphite products that we are familiar with?

1. Use as a conductive material

When smelting various alloy steels, iron alloys or producing calcium carbide (calcium carbide) and yellow phosphorus in electric arc furnaces or submerged electric furnaces, strong currents are introduced through carbon electrodes (or continuous self-baking electrodes—that is, electrode pastes) or graphitized electrodes. The smelting area of the electric furnace generates an arc, which converts electrical energy into heat energy, and the temperature rises to about 2000 degrees Celsius, so as to meet the requirements of smelting or reaction. Metal magnesium, aluminum, and sodium are generally prepared by molten salt electrolysis. At this time, the anode conductive materials of the electrolytic cell are graphitized electrodes or continuous self-baking electrodes (anode paste, sometimes prebaked anodes). The temperature of molten salt electrolysis is generally below 1000 degrees Celsius. Graphitized anodes are generally used as anode conductive materials for salt solution electrolyzers producing caustic soda (sodium hydroxide) and chlorine gas. The conductive material of the furnace head of the resistance furnace used in the production of emery (silicon carbide) also uses graphitized electrodes. In addition to the above uses, carbon and graphite products are widely used as conductive materials in the motor manufacturing industry as slip rings and brushes, in addition to carbon rods in dry batteries, arc carbon rods for searchlights or arc light generation, and anodes in mercury rectifiers Wait.

2. Use as refractory material

Because carbon and graphite products can withstand high temperature and have good high temperature strength and corrosion resistance, many metallurgical furnace linings can be built with carbon blocks, such as the bottom, hearth and hearth of ironmaking furnaces, ferroalloy furnaces and calcium carbide furnaces. lining, bottom and sides of aluminum electrolytic cells. Many crucibles for smelting precious metals and rare metals, and graphitizing crucibles for melting quartz glass, etc., are also processed from graphitized blanks. Carbon and graphite products used as refractory materials should generally not be used in an oxidizing atmosphere. This is because carbon or graphite is rapidly ablated at high temperatures in an oxidizing atmosphere.

3. Use as a corrosion-resistant structural material

The graphitized electrode impregnated with organic resin or inorganic resin has the characteristics of good corrosion resistance, good thermal conductivity and low permeability. This impregnated graphite is also called impermeable graphite. It is widely used in the production of various heat exchangers, reaction tanks, condensers, combustion towers, absorption towers, coolers, heaters, filters, pumps and other equipment, and is widely used in petroleum refining, petrochemical, hydrometallurgy , acid and alkali production, synthetic fiber, papermaking and other industrial sectors, can save a lot of stainless steel and other metal materials. The production of impermeable graphite has become an important branch of the carbon industry.

4. Use as wear-resistant and lubricating material

In addition to the characteristics of high chemical stability, carbon and graphite materials also have good lubricating properties. Under the conditions of high speed, high temperature and high pressure, it is often impossible to use lubricating oil to improve the wear resistance of sliding parts. Graphite wear-resistant materials can work in corrosive media at temperatures from -200 to 2000 degrees Celsius and at very high sliding speeds (up to 100 m/s) without lubricating oil. Therefore, many compressors and pumps that transport corrosive media widely use piston rings, sealing rings and bearings made of graphite materials. They operate without the addition of lubricants. This wear-resistant material is impregnated with ordinary carbon or graphite material through organic resin or liquid metal material. Graphite emulsions are also good lubricants for many metalworking processes (wire drawing, tube drawing, etc.).

5. As a high-temperature metallurgy and ultra-pure material

Structural materials for production, such as crystal growth crucibles, regional refining vessels, supports, fixtures, induction heaters, etc. for the production of single crystal silicon, are all processed from high-purity graphite materials. Graphite heat shields and bases used in vacuum smelting, high temperature resistance furnace tubes, rods, plates, grilles and other components are also processed from graphite materials.

6. As a casting mold and a stamping mold

The use of carbon and graphite materials has a small thermal expansion coefficient and good resistance to rapid cooling and rapid heating, so it can be used as a mold for glassware and a mold for ferrous metals, non-ferrous metals or rare metals. Castings obtained with graphite casting molds have a size, smooth surface, and can be used directly without processing or with a little processing, thus saving a lot of metal. In the production of powder metallurgy processes such as cemented carbide (such as tungsten carbide), graphite materials are usually used to process press molds and boats for sintering.

Seven, the use of graphite in the atomic energy industry and military industry Because of its good neutron deceleration performance, it has been used as a deceleration material in atomic reactors. Graphite reactor is one of the more atomic reactors at present. Graphite materials for atomic reactors must be extremely pure. Some specially treated graphites (such as infiltrating high-temperature resistant materials on the surface of graphite), recrystallized graphite, and pyrolytic graphite have better stability at extremely high temperatures and a higher strength-to-weight ratio. Therefore, they can be used to make nozzles for solid-fuel rockets, nose cones for missiles, and parts for aerospace equipment.