Scope, formula and properties of tungsten

What is tungsten? The main properties of this element are based on the features of its chemical structure. Given the relevance of tungsten, it is necessary to disassemble its structure in more detail.

The position in the periodic table

Considering the basic properties of tungsten, we begin with the fact that it has a 74th order number. Under normal conditions, it is a transition metal with a silver-silver color. Tungsten is solid, has a metallic luster. This is the most refractory element, the greater the melting point has only carbon. ² 5p ⁶ 5d ⁴ 6s ² , E _ион (Ме => Ме ⁺ + e) = 7,98 э В. Electronic formula: KLMN5s ² 5p ⁶ 5d ⁴ 6s ² , E _ion (Me => Me ⁺ + e) = 7.98 eV .

History of origin

Its unusual name is given to the metal by the mineral wolframite. "Wolf foam" has been known since the 16th century. This unusual name for the mineral is explained by the presence of tin ores in it . Tungsten interfered with melting tin, transferring it to foam from slag. What physical properties of tungsten became the basis of its wide application in industry? In the US, this metal was called a "heavy stone".

At the end of the 18th century, Scheele, when processing the mineral with nitric acid, obtained scheelite, obtaining tungsten trioxide. A little later, the brothers Eliar managed to get tungsten oxide from Saxon wolframite. It was these chemists that revealed certain chemical properties of tungsten.

Being in nature

Is there pure tungsten in nature? The chemical properties of this metal suggest its presence in the earth's crust for the most part in the form of compounds. For example, there is a mixture of oxides of manganese, iron, tungsten. For industrial use, ferberite and gubnerite compounds are chosen. In addition to tungsten, iron and manganese are present in them. The physical properties of tungsten make it possible to separate the metal from tungsten minerals. In them, its concentration does not exceed two percent. Among the largest deposits of tungsten we note China, USA, Kazakhstan. In addition, significant reserves of this metal have been identified in South Korea, Bolivia, Russia, Portugal. The excellent physical properties of tungsten suggest its significant industrial production. In the world annually produce about 50 thousand tons of this refractory element. The main exporters of tungsten are South Korea, China, Austria. Among the importers of refractory metal, the leadership palm belongs to Great Britain, Japan, the USA, Germany.

Production features

The tungsten is obtained through an intermediate stage, which implies the isolation of tungsten trioxide from the ore concentrate. Further, it is restored to a powdered metal. A similar stage occurs at a temperature of about 700 degrees Celsius. What physical properties of tungsten are the basis of this technology? Its high melting temperature allows powder powder metallurgy to be subjected to pressing, sintering in an atmosphere of hydrogen at a temperature of about 1300 degrees Celsius. Further, an electric current is passed through the obtained tungsten. When the metal is heated to a temperature of 3000 degrees, a monolithic material is observed. By zone melting, subsequent purification and production of a single crystal metal is carried out.

Properties

What are the characteristics of tungsten? Its chemical properties are based on a high melting point. The element exhibits a valence of 2 to 6. The most stable is tungsten with a valency of six. The metal is characterized by increased corrosion resistance. It is not oxidized in air at room temperature. In tungsten oxide, it is converted only when the temperature reaches the white knee. In the electrochemical series of metal stress, this element is located after hydrogen, so it does not dissolve in dilute hydrofluoric and sulfuric acids. Tungsten is able to dissolve in hydrogen peroxide, as well as in a mixture of hydrofluoric and nitric acids.

In the presence of oxidants, this metal is able to react with molten alkalis. Initially, the interaction proceeds slowly enough, but after reaching a temperature of 400 degrees, spontaneous heating of the metal is observed, which accelerates the reaction. Tungsten in a mixture of hydrofluoric and nitric acids forms hexafluorotungstic acid. In the maximum amount in the industry, tungsten anhydride is used. Tungstates have the ability to create polymer anions. This metal is the basis of refractory materials in modern metallurgy.

Applications

How can tungsten carbide be used ? The properties of this compound make it possible to isolate pure tungsten from it. The ductility and refractoriness of the metal made it the basis for creating filaments in numerous lighting devices. In addition, tungsten is used in vacuum tubes and kinescopes. Since this element has a high density, it has become the base for the production of heavy alloys. They are indispensable in the creation of counterweights, subcaliber and armor-piercing cores, ultra-high-speed rotors of gyroscopes for the creation of ballistic missiles. In large volumes, tungsten is used in argon-arc welding as an electrode. Alloys, which contain tungsten in their composition, have high heat resistance, acid resistance, they are resistant to mechanical deformations. These characteristics make it possible to use them for the manufacture of surgical instruments, armor tanks, aircraft engines, containers for the placement of radioactive substances. It is tungsten that is an important component for the production of high-quality steel grades.

It is also used in high-temperature vacuum furnaces in the form of a heating element. In an alloy with rhenium, thermocouples are created from it for such furnaces.

Conclusion

It is thanks to the high density of tungsten that the metal is suitable for protecting the surface from ionizing radiation. Increased hardness and refractoriness of metal create significant difficulties with its processing. To solve the problem, nickel, copper, and iron are introduced. The durability of tungsten made it in demand in the manufacture of structural materials in modern engineering.

It is necessary for milling, chiselling, turning, drilling wells. For example, the winner consists of tungsten carbide. This mixture is applied to the drills used to create holes in the concrete. Tungsten sulfide acts as a high-temperature lubricant. It is in demand in production. Some of the tungsten compounds are used in the form of pigments and catalysts. Apply compounds of this metal and as an alloying element in alloys and steels based on iron. Biological value does not have metallic tungsten.