Three Derivatives of Graphite
Graphite is a kind of allotrope of carbon, which is gray black and opaque solid. It can be divided into artificial graphite and natural graphite. Besides, graphite is also widely used in the production of refractories, conductive materials, wear-resistant materials, lubricants, high-temperature sealing materials, corrosion-resistant materials, thermal insulation materials, adsorption materials, friction materials, and radiation-resistant materials. These materials are widely used in metallurgy, petrochemical industry, mechanical industry, electronic industry, nuclear industry, and national defense.
Although graphite is usually stable, graphite powder plays a vital role in the production.
Graphite powder is soft, black-gray, greasy, and can contaminate paper. The hardness is 1-2, and it can be increased to 3-5 along the vertical direction with the increase of impurities. The specific gravity is 1.9-2.3. Under the condition of oxygen isolation, its melting point is above 3000 ℃, which is one of the most temperature resistant minerals. Under average temperature, the chemical properties of toner are relatively stable, insoluble in water, dilute acid, dilute alkali and an organic solvent; the material has high-temperature resistance and conductivity, which can be used as refractory, conductive material and wear-resistant lubricating material.
Graphite anode is a kind of graphite plate, block, or bar used as the anode of electrolyzer in the electrolysis industry. There are two kinds of electrolysis processes using graphite anode, and one is aqueous solution electrolysis; the other is molten salt electrolysis. The chloralkali industry, which produces caustic soda and chlorine gas by electrolyzing salt aqueous solution, is the largest user of graphite anode. Also, some electrolyzers use molten salt electrolysis to provide light metals such as magnesium, sodium, tantalum, and rare metals, and graphite anode is also used.
Carbon nanotubes (CNTs), also known as Ba based tubes, are one-dimensional quantum materials with unique structures (radial size is nanometer, axial dimension is micron, and both ends of the machines are sealed). Carbon nanotubes can be regarded as curled graphene sheets so that they can be divided into single-walled carbon nanotubes and multi-walled carbon nanotubes according to the number of graphene sheets. Carbon nanotubes are mainly composed of hexagonal carbon atoms, which form several to dozens of concentric tubes. The distance between layers is about 0.34nm, and the diameter is generally 2 ~ 20nm. According to the different orientation of the carbon hexagon along the axial direction, it can be divided into three types: zigzag, armchair, and spiral. Among them, helical CNTs have chirality, while zigzag and armchair CNTs have no chirality.
Many composite materials with excellent properties can be made by using the properties of carbon nanotubes. For example, the plastics reinforced by carbon nanotubes have unique mechanical properties, good conductivity, corrosion resistance, and radio wave shielding. The carbon nanotube composite with cement as a matrix has excellent impact resistance, anti-static, wear resistance, high stability, and is not easy to affect the environment. Carbon nanotubes reinforced ceramic composites have high strength and excellent impact resistance. Due to the defects of the five-membered ring, the reaction activity of carbon nanotubes is enhanced. Under the condition of high temperature and other substances, carbon nanotubes are easy to open at the end face, forming a tube, which is easily infiltrated by metal, and forming metal matrix composite with metal. Such materials have high strength, high modulus, high-temperature resistance, small coefficient of thermal expansion, and strong resistance to thermal change.
Graphite plays a vital role in human industrial production and life, ranging from pencil lead for writing to national defense and military materials. At the same time, as we can see in this paper, graphite has many derivative products, which also play a unique role in their respective fields. It can be predicted that graphite will shine even more in the future!