What is tungsten? The main properties of this element are based on the features of its chemical structure. Given the demand for tungsten, it is necessary to analyze its structure in more detail.
Position in the periodic table
Considering the basic properties of tungsten, we begin with the fact that it has the 74th serial number. Under normal conditions, it is a transition metal having a gray-silver color. Hard tungsten, has a metallic luster. This is the most refractory element, only carbon has a higher melting point. Electronic formula: KLMN5s 2 5p 6 5d 4 6s 2 , E ion (Me => Me + + e) = 7.98 eV .
Origin history
This unusual name for this metal is due to the mineral tungsten. Wolf Foam has been known since the 16th century. This unusual name of the mineral is explained by the presence of tin ores in it. Tungsten prevented smelting tin, converted it to foam from slag. What physical properties of tungsten became the basis of its widespread use in industry? In the US, this metal was called the "heavy stone."
At the end of the 18th century, the Swee Scheele, when processing the mineral with nitric acid, received scheelite, obtaining tungsten trioxide. A little later, the Eliar brothers managed to get tungsten oxide from Saxon wolframite. It was these chemists who revealed some chemical properties of tungsten.
Being in nature
Is tungsten pure 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 guberite compounds are chosen. In addition to tungsten, iron and manganese are present in them. The physical properties of tungsten allow metal to be isolated from tungsten minerals. In them, its concentration does not exceed two percent. Among the largest deposits of tungsten, we note China, the USA, and Kazakhstan. In addition, significant ore reserves of this metal were identified in South Korea, Bolivia, Russia, and Portugal. The excellent physical properties of tungsten suggest its substantial industrial production. About 50 thousand tons of this refractory element are produced annually in the world. The main exporters of tungsten consider South Korea, China, Austria. Among importers of refractory metal, the palm of leadership belongs to the UK, Japan, USA, Germany.
Production Features
The production of tungsten is carried out through an intermediate stage, which involves the separation of tungsten trioxide from the ore concentrate. Next, it is restored to a powdered metal. A similar stage occurs at a temperature of about 700 degrees Celsius. What physical properties of tungsten underlie this technology? The high temperature of its melting allows using powder metallurgy to expose the powder to pressing, sintering in a hydrogen atmosphere at a temperature of about 1300 degrees Celsius. Next, 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 cleaning and obtaining of single-crystal metal is carried out.
The properties
What characteristics does tungsten have? Its chemical properties are based on a high melting point. The element exhibits a valency of 2 to 6. The most stable is tungsten with a valency of six. The metal is characterized by increased corrosion resistance. It does not oxidize in air at room temperature. It turns into tungsten oxide only when the temperature of the white knee is reached. In the electrochemical series of metal stresses, this element is located after hydrogen; therefore, it does not dissolve in dilute hydrofluoric and sulfuric acids. Tungsten is capable of dissolving in hydrogen peroxide, as well as in a mixture of hydrofluoric and nitric acids.
In the presence of oxidizing agents, this metal is capable of reacting with molten alkalis. At first, the interaction proceeds rather slowly, 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 hexafluorotungsten acid. The maximum amount of tungsten anhydride is used in industry. Tungstates have the ability to create polymer anions. This metal is the basis of refractory materials in modern metallurgy.
Fields of application
How can tungsten carbide be used? The properties of this compound make it possible to isolate pure tungsten from it. Plasticity and refractoriness of the metal made it the basis for creating incandescent filaments in numerous lighting fixtures. In addition, tungsten is used in vacuum tubes and picture tubes. Since this element has a high density, it has become the basis for the production of heavy alloys. They are indispensable for creating counterweights, sub-caliber and armor-piercing cores, ultra-high-speed gyroscope rotors for creating ballistic missiles. In large volumes, tungsten is used in argon-arc welding as an electrode. Alloys that contain tungsten in their composition have high heat resistance, acid resistance, they are resistant to mechanical deformation. Such characteristics allow them to be used for the production of surgical instruments, armor of tanks, aircraft engines, containers for the placement of radioactive substances. It is tungsten that is an important component for the manufacture 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
Due to the high density of tungsten, the metal is convenient for protecting the surface from ionizing radiation. The increased hardness and refractoriness of the metal create significant difficulties with its processing. To solve the problem, nickel, copper, and iron are introduced into the composition. The durability of tungsten has made it popular in the manufacture of structural materials in modern mechanical engineering.
It is necessary for milling, chiselling, turning, drilling. For example, the win consists of tungsten carbide. This mixture is applied to the drills used to create holes in 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. Compounds of this metal are also used as an alloying element in alloys and steels based on iron. Metallic tungsten has no biological value.