Graphite is a substance that is found in nature. This is one of the modifications of carbon, which is characterized by a specific crystal lattice. This determines the properties that graphite possesses. In nature, carbon occurs in two main forms. It is graphite and diamond. Their chemical formula is identical, but the physical properties are radically different.
It is the structure of the crystal lattice that affects these characteristics. It has free electrons that determine the physical properties of matter. Graphite, the density, types and application of which are interesting for many industries, it is worth considering in more detail.
Basic properties
Graphite is a gray substance with a metallic sheen. It has a high thermal conductivity (3.55 W / deg./cm). Due to this, graphite is actively used in various industries. This indicator is higher than that of a brick, which is explained by the presence of mobile electrons in the crystal lattice. They also contribute to good electrical conductivity. In all aggregate states, this substance is characterized by a low current resistance (from 0.4 to 0.6 Ohms).
Graphite is an inert substance that is not soluble by chemically active components. This is possible only when it enters the environment of molten metal with a high boiling point. Under such conditions, graphite melts completely, forming carbides.
Low friction coefficient and high melting point determine good sealing properties. The density of graphite (kg / m3) is 2.23. But at the same time, the material bends and cuts well.
Structure
Considering what the density of graphite, as well as properties and types, it is necessary to pay attention to its structure. This is a layered substance. Its carbon atoms line up in a crystal lattice, similar to honeycombs. Hexagons in one layer fit snugly together. However, the connection between each level is weak. It is this feature that makes it easy to break graphite.
On the Mohs scale, the hardness of the material is unity. For comparison, in diamond this indicator is 10, and in granite - 5. At a temperature of 1500 ° C, according to scientists, the crystal lattice of graphite can be transformed into diamond.
In the process of industrial processing, the structure of the substance changes. At the same time, unequal properties are determined for different grades of graphite. If the extracted material was not processed artificially, this is a natural type of substance.
Natural graphite
Graphite, the density and properties of which differ significantly depending on the brand of the manufacturer, is found in 2 basic variants under natural conditions. The first type is called hexagonal. It has a crystal lattice in which half of the atoms in each layer are above and below the center of the hexagon.
The second modification is rhombohedral. Every fourth layer repeats the first. This modification in nature is found only in the form of impurities. If this substance is heated at a temperature of 2500-3300 K, then its crystal lattice will turn into a hexagonal one. Under natural conditions, the material is more often found in this form.
Composition
In nature, graphite is never found in its pure form. It contains a fairly large amount of ash (sometimes up to 20%). It consists of many different compounds (FeO, MgO, CuO, CaO, etc.). Up to 2% of the mass in natural graphite can be occupied by gases. Bitumen and water may also be present.
The density of graphite powder varies depending on the dispersion, the presence of pores. The above value may be reduced to 2.09 kg / m 3 . The graphite is oily to the touch. If you take it with your hands, a characteristic mark will remain on the fingers. Therefore, rods for a simple pencil are created from such material. He leaves a clear mark on paper.
Artificial Graphite
For production, it is very important to consider what the density of graphite is. Physics makes it clear that the higher the density of this substance, the greater its thermal conductivity. Artificial graphite is characterized by high purity (up to 99%). It also significantly increases the density of the material.
The production of purified graphite is carried out by thermochemical and thermomechanical effects. For each industry, a substance is produced with a certain set of qualities. This allows you to meet the needs of industry in graphite with specified physical characteristics.
Labeling of substances created artificially includes a breakdown of the types of material by purpose. There are foundry, carbon, battery, elemental, lubricating and pencil graphite. There are also special grades used in nuclear reactors.
Scope of application
During production, certain properties of graphite are set . The use of this substance is completely dependent on them. Graphite is used in metallurgy in the manufacture of refractory molds or buckets, containers. In the casting process, the powder of the present substance is used as a lubricant. One of the components of refractory bricks is also graphite. It is added to the mixture in the manufacture of plastics.
For the manufacture of electrical contacts this material is also used. This is facilitated by the conductive properties of the substance.
Perhaps, pencils are known to every person. This material is also used in the manufacture of certain types of paints. In this case, black (and not gray) graphite is used. This paint has anti-corrosion properties.
Artificial diamonds are obtained from the presented natural mineral . They are used in the manufacture of heavy duty cutting tools. In mechanical engineering, graphite powder acts as a material for bearings, as well as piston and o-rings. In the form of a lubricant, it is suitable for processing bicycle chains, car springs, door hinges.
Even in many drugs, graphite can be found.
Application in the food industry
The presented substance is also widely used in the food industry. To do this, during production, it is subjected to certain processing. The density of iron, ethyl alcohol, graphite and sugar, for obvious reasons, is different. But the material presented can both contain and be part of some substances. It is found in paraffins, esters, alcohol, and even in sugar.
You can verify this if you conduct a simple experiment. First you need to take a piece of sugar. It is placed on a hard cover and covered with a cap (you can use a thimble). Then the metal, which is covered with sugar, is heated strongly. Acrid smoke will come out from under the thimble. If you bring a match to it, the gas will burn.
When the smoke ceases to be emitted, you can remove the thimble. The black mass remains on the lid. This is coal. It is carbon, of which graphite is composed.
Being in nature
Graphite, the density of which depends on its purity, is found in nature in rather large quantities. About 600 thousand tons of this substance are mined annually around the world. Its largest reserves are concentrated in Mexico, the Czech Republic, China, Ukraine, Brazil, Russia, Canada and South Korea.
Since ancient times, graphite deposits have been of interest to mankind. Today, these natural resources are being developed to provide industry with materials with the required qualities. Graphite is found in granites, calcareous rocks, mica or gneiss in the form of fibrous or crystalline inclusions. Extraction is carried out by open and underground methods.
Graphite cost
Graphite, the density and purity of which affect its cost, is now sold at fairly reasonable prices. This is influenced by the size of its crystals, as well as the carbon content. The higher it is, the more expensive graphite is. With a sufficiently high carbon content, the physical properties of the material increase . It is valuable for the industry of various industries.
Today, the average cost of graphite is about 45 rubles / kg. If it was processed artificially, the cost increases significantly. Also, the price of a natural mineral depends on the location of the deposit.
Having become acquainted with the basic properties and characteristics of graphite, we can conclude that both the cost and the technical quality of the material depend on its density. Therefore, the mineral extracted in nature is subject to further processing. This improves its quality.