2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16
Graphite is a substance that occurs naturally. This is one of the modifications of carbon, which is characterized by a certain crystal lattice. This determines the properties that graphite has. Carbon occurs in nature in two main forms. These are graphite and diamond. Their chemical formula is identical, but their 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, whose density, types and scope are interesting for many industries, is worth considering in more detail.
Basic Features
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 figure 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 states of aggregation, this substance is characterized by low current resistance (from 0.4 to 0.6 ohms).
Graphite is an inert substance that is not dissolved by chemically active components. This is possible only when it enters the medium of molten metal with a high boiling point. Graphite under such conditions melts completely, forming carbides.
Low coefficient of friction and high melting point result in 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 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 honeycomb-like crystal lattice. Hexagons in one layer fit snugly together. However, the relationship 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 one. For comparison, this indicator is 10 for diamond, and 5 for porcelain stoneware. At a temperature of 1500 ° C, according to scientists, the crystal lattice of graphite can be transformed into diamond.
During industrial processing, the structure of matter changes. At the same time, different grades of graphite have different properties. If the extracted material has not been processed artificially, it 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 natural conditions in 2 main variants. First typecalled 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 one. This modification occurs in nature 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 can be reduced to 2.09kg/m3. Graphite is greasy to the touch. If you take it with your hands, a characteristic mark will remain on your fingers. Therefore, rods for a simple pencil are created from such material. It leaves a clear mark on paper.
Artificial graphite
For production, it is very important to consider what is the density of graphite. Physics makes it clear that the greater the density of this substance, the greater its thermal conductivity. Artificial graphite is characterized by high purity (up to 99%). It also greatly increases the density of the material.
The production of refined graphite is carried out by thermochemical and thermomechanical influences. For each branch of production, a substance with a certain set of qualities is produced. This makes it possible to meet the needs of the industry in graphite with given physical characteristics.
Labeling of artificial substances includes a breakdown of material types by destination. There are foundry, electrocarbon, 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 entirely up to them. Graphite is used in metallurgy in the manufacture of refractory molds or ladles, containers. In the casting process, the powder from the presented 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.
This material is also used for the manufacture of electrical appliance contacts. This is facilitated by the electrical conductive properties of the substance.
Graphite pencils are known, perhaps, to every person. This material is also used in the production of some types of paints. In this case, it is black (and not gray) graphite that is used. This paint has anti-corrosion properties.
Artificial diamonds are obtained from the presented natural mineral. They are used whenproduction of heavy-duty cutting tools. In mechanical engineering, graphite powder acts as a material for bearings, as well as piston and sealing rings. As a lubricant, it is suitable for processing bicycle chains, car springs, door hinges.
Even many medicines contain graphite.
Food Applications
The presented substance is also widely used in the food industry. To do this, during production, it undergoes certain processing. The density of iron, ethyl alcohol, graphite and sugar, for obvious reasons, is different. But the presented material can both contain and be part of some substances. It is found in paraffins, esters, alcohol and even sugar.
This can be verified by a simple experiment. First you need to take a piece of sugar. It is placed on a hard lid and covered with a cap (you can use a thimble). Then the metal with which the sugar is covered is heated strongly. Over time, acrid smoke will come out from under the thimble. If you bring a match to it, the gas will burn.
When the smoke stops emitting, you can remove the thimble. There is a black mass on the lid. This is coal. It is the carbon that graphite is made of.
Being in nature
Graphite, whose density depends on its purity, is found in nature in fairly large quantities. About 600 thousand tons of this substance are mined annually all over the world. The largestits reserves are concentrated in Mexico, the Czech Republic, China, Ukraine, Brazil, Russia, Canada and South Korea.
Since ancient times, graphite deposits aroused the interest of mankind. Today, these natural resources are being developed in order 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. Mining is carried out by open pit and underground methods.
Graphite cost
Graphite, the density and purity of which affect its value, 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. This is valuable to industry in a wide variety of 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.
Familiarizing with the main properties and characteristics of graphite, we can conclude that both the cost and technical qualities of the material depend on its density. Therefore, the mineral mined in nature is subject to subsequent processing. This enhances its quality.
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