The characteristics of natural graphite mainly include the following aspects:
Physical properties: Natural graphite is iron black, steel gray, has a metallic luster, is opaque, has a low hardness, a vertical cleavage plane hardness of 3 to 5, and a parallel cleavage plane hardness of 1 to 2. Its density is 2.09 to 2.23 g/cm³, has a greasy feel, and is easy to contaminate fingers.
Chemical properties: Natural graphite has good chemical stability and is resistant to acid, alkali and organic solvent corrosion. Its melting point is above 3000℃ and its boiling point is 4250℃. Even under ultra-high temperature arc burning, the weight loss is very small and the thermal expansion coefficient is small.
Mechanical properties: Natural graphite has high strength and toughness, and its strength increases with increasing temperature. At 2000℃, the strength of graphite doubles.
In addition, graphite also has good lubrication and thermal shock resistance, and can remain stable in an environment with drastic temperature changes.
Electrical properties: Natural graphite has excellent electrical conductivity, which is one hundred times higher than that of general non-metallic minerals. Its thermal conductivity is also better than that of metal materials such as steel, iron, and lead. The thermal conductivity coefficient decreases with increasing temperature, and it even becomes an insulator at extremely high temperatures.
Application areas: Due to these excellent properties, natural graphite is widely used in many fields. For example, as a refractory material, steelmaking carburizer, conductive material, lubricant, sealing material, etc.
In addition, high-purity graphite is also used as a neutron moderator in atomic reactors, and in the manufacture of crucibles, electrodes, brushes, dry batteries, etc.