Views: 0 Author: IQSDirectory Publish Time: 2022-10-20 Origin: IQSDirectory
Graphite can be mined or synthetically produced from petroleum byproducts from the oil refining process. Mined or natural graphite is known as plumbago, black lead, and mineral carbon and is found in layers in a lamellar shape with a grey to black luster, a greasy feel, and in flaky, crystalline, and amorphous forms. Its quality depends on its physical properties.
Synthetic graphite is made by high temperature treatment of amorphous carbon materials, which include calcined petroleum coke and coal tar pitch that are composed of graphitizable carbon. Its porosity plays a large role in controlling its thermal expansivity with a temperature that depends on the strength of its polygranular structure
Synthetic graphite is not as crystalline as natural graphite but has a higher purity carbon content. The two types of synthetic graphite are electrographite and graphite blocks. Electrographite is produced in electric ovens, while graphic blocks, or isotropic graphite, is made from coke that has a different structure than that used to produce electrographite.
Synthetic or artificial graphite has superior properties compared to natural graphite. Its excellent purity allows it to be more predictable and controllable making it the perfect option for specialized industries. The manufacturing process that is used to produce synthetic graphite determines its physical and chemical properties.
Synthetic graphite powder is made by heating petroleum coke or petroleum pitch above their graphitization temperature. In some instances, it is collected by screening lathe turnings of electrodes and nipples.
Synthetic graphite is used in several industries that include electronics, the military, aerospace, defense, and nuclear power.
Graphite electrodes are used in the steel making process to melt scrap iron and steel.
Special grades of synthetic graphite are used as matrix and neutron moderators in nuclear and fusion reactors.
Several commercial products are made from synthetic graphite due to its durability and long life, which include fishing rods, golf club shafts, bicycle frames, sports car body panels, the fuselage of the Boeing 787, and pool sticks.
Natural graphite is like mica and consists of sheets of flat molecules held together by Van der Waals forces, a dependent weak interaction between atoms and molecules. These weak forces make graphite soft enough to erode by friction.
The two forms of graphite are hexagonal and rhombohedral that have similar properties but different graphene layers. Each type can be converted and processed into the other form.
Graphite‘s thermal stability and electrical and thermal conductivity makes it ideal for use as electrodes and high temperature refractory production. The one drawback to graphite uses is its ability to oxidize at temperatures over 700°C.
The forming of graphite is the reaction of carbon compounds with hydrothermal solutions, magmatic fluids, or the crystallization of magmatic carbon.
Graphite is used for refractory production, batteries, steel, brake linings, foundry facings, and lubricants.
Though the material in pencils has been referred to as lead for many years, in actuality, it is a form of clay graphite.
Crucible production began with clay graphite but has progressed to alumina graphite and silicon carbon graphite. Graphite is also used in bricks as a lining for steel blast furnaces.
With the rise in portable electronics, graphite has gained greater use in the production and fabrication of batteries. It is used twice as much as lithium carbonate.
Graphite is used to raise the carbon content of molten steel and as a lubricant for dies.
In the production of brake linings, graphite has become a replacement for asbestos.
A graphite coating is used for the lining of molds making it easier to remove cast parts. Its high temperature resistance makes it easier to separate parts after cooling.
A graphite crucible is a container used for melting and casting non-ferrous, non-iron, metals such as gold, silver, aluminum, and brass.
The quality of a graphite crucible is determined by how it is manufactured, which influences its structure, density, porosity, and strength.
Graphite crucibles are ideal for melted metal processes because they are non-reactive and able to survive extremely high temperatures.
The type of metal to be processed determines the type of graphite crucible that will be used.
The manufacturing of graphite crucibles involves the use of clay-graphite-ceramic bonded or silicon-carbide-carbon bonded materials that use the refractory properties of silicon and graphite to conduct heat but add structural strength.
There are two forms of graphite used in the production of graphite crucibles - synthetic and natural.