Graphite Properties, Applications and Optical features.

Like diamonds, graphite is a form of natural carbon crystals with atoms arranged in an opaque deep red to black hexagonal structure. It appears in the form of hexagonal crystals, flexible sheets, scales or large blocks. It may be earthy, granular, or compact. Graphite is formed by the metamorphism of carbonaceous deposits and the reaction of carbon compounds with hydrothermal solutions. It exists naturally in this form and is the most stable form of carbon under standard conditions. Under high pressure and high temperature, it will transform into diamonds. It looks very different from a diamond and is located at the other end of the hardness scale. Its flexibility is due to the way the carbon atoms are bonded to each other, and the six carbon atoms are arranged on a horizontally spaced plate. The atoms are firmly bonded within the ring, but very weakly bonded between the thin plates. It is used for pencils and lubricants. Its high conductivity makes it useful for electronic products, such as electrodes, batteries, and solar panels.
 

Chemical Properties

Chemical Classification	Native element
Formula	C

Graphite Physical Properties

Color	Steel gray to black
Streak	Black
Luster	Metallic, sometimes earthy
Cleavage	Perfect in one direction
Diaphaneity	Opaque
Mohs Hardness	1 to 2
Crystal System	Hexagonal
Tenacity	Flexible
Density	2.09 – 2.23 g/cm3 (Measured)    2.26 g/cm3 (Calculated)
Fracture	Micaceous

Graphite Optical Properties

Anisotropism	Extreme
Color / Pleochroism	Strong
Optic Sign	Uniaxial (-)
Birefringence	extreme birefringence

 
 
The appearance of graphite
It is formed by the deterioration of carbon-containing deposits by the reduction of carbon compounds. The main component in igneous rocks. It occurs in metamorphic rocks due to the reduction of sedimentary carbon compounds in metamorphic rocks. It can also be seen in magmatic rocks and meteorites. The minerals related to it are quartz, calcite, mica, and tourmaline. China, Mexico, Canada, Brazil, and Madagascar are the main export sources of minerals.
 
Synthetic graphite
Synthetic graphite is a material composed of graphitic carbon, which is obtained by graphitizing non-graphite carbon from hydrocarbons by CVD at a temperature higher than 2500 K, through decomposition of thermally unstable carbides or from supersaturated carbon Obtained by crystallization in the molten metal.
 
The term "artificial graphite" is often used synonymously with synthetic graphite. However, the term "synthetic graphite" is preferred because their crystals are considered to be composed of carbon macromolecules. The term synthetic graphite is mainly used for graphitized carbon, although the term CVD includes pyrolytic graphite as well as carbide decomposition residues. Such common usage is the same as the definition above. The most important synonym for synthetic graphite is Acheson graphite and electrophotography.
 
Applied area
Natural graphite is mainly used in refractory materials, batteries, steelmaking, expanded graphite, brake pads, casting surfaces and lubricants.
Crucibles began to use very large flake graphite, while carbon-magnesite bricks did not require such large flake graphite. For these and other products, the required flake size now has greater flexibility, and amorphous graphite is no longer limited to low-end refractory materials.
In the past 30 years, the use of graphite in batteries has increased. Among the main battery technologies, natural and synthetic materials can be used to construct electrodes.
The demand for batteries, for example, the lithium-ion battery in the new electric car contains nearly 40 kilograms of graphite.
Natural graphite in steelmaking is mainly used to increase the carbon content in molten steel, and it can also be used to lubricate molds used to extrude hot steel.
Natural amorphous and fine flake graphite is used in brake linings or brake shoes of heavy (non-automotive) vehicles, and it becomes more and more important as it needs to replace asbestos.
Foundries for mold cleaning are amorphous or thin flake-like water-based coatings. Using it to paint the inside of the mold and let it dry will leave a fine graphite coating that simplifies the separation of the casting after the molten iron is cooled.
 
Applications of synthetic graphite
High focus pyrolytic graphite (HOPG) is the highest quality synthetic graphite. In scientific research, it is used as a length standard for scanner calibration, especially on scanning probe microscopes.
Its electrodes are charged, melting scrap iron and steel in electric arc furnaces (most steel furnaces), and sometimes direct reduced iron (DRI). They are made from petroleum coke after being mixed with coal tar tar.
Graphite carbon electrodes are also used in electrolytic aluminum smelting. In the discharge process (EDM), synthetic discharge electrodes are used on a smaller scale to make plastic injection molds.
Special grades of synthetic graphite, such as gilsocarbon, can be used as a matrix and neutron moderator in nuclear reactors. The low neutron cross section is also recommended for use in the recommended fusion reactor.
It (carbon) fibers and carbon nanotubes are also used in carbon fiber reinforced plastics and heat-resistant composite materials, such as reinforced carbon-carbon (RCC). Commercial structures made of carbon fiber graphite composite materials include fishing rods, golf shafts, bicycle frames, sports car body panels, the body of the Boeing 787 Dreamliner and the body of the swimming pool marker pole.
Modern smokeless powders are coated with graphite to prevent static charge buildup.
It is used in at least three radar absorbing materials. Sumpf and Schornsteinfeger are used in U-shaped snorkels to reduce the radar cross section and are mixed with rubber. The F-117 Nighthawk was also used on floor tiles for secretly striking fighter jets.
Graphite composites are used as absorbers for high-energy particles (for example, in LHC beam collectors).
Graphite recycling
The most common method of graphite recovery occurs when synthetic graphite electrodes are produced and cut into small pieces or discarded on a lathe, or when the electrodes (or other electrodes) are used up to the electrode holder. Replace the old electrodes with new electrodes, but most of the old electrodes still exist. After crushing and sizing, the obtained graphite powder is mainly used to increase the carbon content of molten steel. Refractories containing refractory materials are sometimes recycled, but they are usually not caused by graphite: the largest bulk materials (such as carbon magnesia bricks containing only 15% to 25% graphite) usually contain very little graphite. However, some recovered carbon magnesite.
 
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