Density of tungsten. Properties and applications of tungsten

What is the density of tungsten? What is the basis of its use? We will seek answers to the questions posed together.

Position in the PS

This chemical element is located in the sixth group of the periodic table. Its serial number is 74, the value of the relative atomic mass is 183.85. The special properties of tungsten are determined by its high melting point. It is considered one of the most refractory metals. Natural tungsten contains five stable isotopes that have similar mass numbers from 180 to 186.

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This chemical element was discovered in the late 18th century. K. Scheele managed to separate it from a mineral in which the metal was contained in the form of an oxide. For a long time tungsten had practically no industrial application, it was not in demand. Only in the middle of the 19th century metal was used as an additive in the manufacture of strong steel.

Content in nature

In the earth's crust, this element is in an insignificant amount. It is not found in free form, it is located only in the form of minerals. Its oxides are used commercially.

Physical properties

19300 is the density of tungsten kg / m3 under normal conditions. The metal forms a volume-concentric cubic lattice. It has a good heat capacity. The high temperature coefficient of tungsten explains its refractoriness. The melting point is 3380 degrees Celsius. The mechanical properties are affected by its pre-treatment. Considering the density of tungsten at 20 s 19, 3 g / cm 3, it can be brought to the state of a single-crystal fiber. This property is used when making wire from it. Under room temperature, tungsten has a slight ductility.

Features of tungsten

The substantial density of tungsten gives certain properties to this metal. It has a rather low evaporation rate, a high boiling point. In terms of electrical conductivity, tungsten is three times lower than that of copper. It is the high density of tungsten that limits the scope of its use. In addition, its use is affected by its increased fragility at low temperatures, the instability to oxidation by air oxygen at low temperatures.

By external characteristics, tungsten has a similarity to steel. It is used for the production of alloys characterized by increased strength. Tungsten is processed only at elevated temperature.

Tungsten Stamps

Not only the density of tungsten, but also the additives used in metallurgy, are reflected on the brand of this metal. For example, BA assumes a mixture of tungsten with aluminum and silicon. The resulting brand is characterized by an increased initial recrystallization temperature, strength after annealing.

VL assumes the addition of tungsten as an additive to lanthanum oxide, which increases the emission properties of the metal.

MB is an alloy of tungsten and molybdenum. Such a composition increases the strength, retains the ductility of the metal after annealing.

Scope of use of tungsten

The unique properties of this metal predetermine its use. In industrial volumes it is used both in pure form and as alloys.

Tungsten in everyday life is used mainly for electrical purposes.

It is used as the main component (alloying element) in the production of high-speed steels. The average content of tungsten is from nine to twenty percent. In addition, it is part of tool steels.

Such forks are used for the manufacture of mills, drills, punches, dies. For example, high-speed steels P6M5 indicate that steel is alloyed with cobalt and molybdenum. In addition, tungsten is contained in magnetic steels, which are subdivided into tungsten-cobalt and tungsten species.

Tungsten in everyday life in its pure form is practically not in demand. Tungsten carbide is a compound of this metal with carbon. The compound is distinguished by high hardness, refractoriness, and also wear resistance. Based on tungsten carbide, instrumental productive hard alloys are produced, containing about 90 percent of tungsten and about 10 percent of cobalt. From hard alloys create cutting parts of drilling and cutting tools.

Varieties of tungsten-based steels

Wear-resistant and high-temperature alloys are based on the refractory properties of tungsten. In the industry, tungsten compounds with chromium and cobalt, which are called stellites, are common. They are applied by welding to wear parts of parts of industrial machines.

"Heavy" and contact alloys are mixtures of tungsten with silver or with copper. They are considered to be sufficiently effective contact materials, therefore they are used for the production of working parts of knife switches, electrodes for spot welding, and also for the manufacture of switches.

In the form of wire, forged products, tungsten ribbons are used in radio engineering, in the manufacture of electric lamps, as well as in radiotechnics. It is this metal that is considered the best material for creating spirals and filaments.

Tungsten rods and wire are necessary for making electric heaters for high-temperature furnaces. Heaters based on tungsten can work in an atmosphere of inert gas, hydrogen, and also in a vacuum.

One of the most important uses of tungsten is welding. It creates electrodes that are used for arc welding. The resulting electrodes are considered non-melting.

Preparation of a refractory metal

How much does tungsten cost? The price per kg is in the range of 900 to 1200 rubles. He is referred to a group of rare metal elements. In addition to tungsten, Rubidium, molybdenum, is also listed here. Rare metals have small scale of use, taking into account their insubstantial content in the earth's crust. None of these metals can be obtained by direct reduction from the raw materials. To begin with, the raw materials are processed into various chemicals. We note that special additional ore dressing is also being carried out before they are fully processed.

In the technological chain of obtaining rare tungsten, three stages are distinguished. First, the ore is decomposed, separating the recovered metal from the mass of the feed, and also concentrating it in the precipitate or in the solution. Further, the preparation of chemically pure compounds is carried out, the isolation is carried out, as well as the purification of the chemical. In the third stage, the metal is recovered from the oxide that has been purified of impurities.

As a starting material for the production of tungsten, wolframite acts. This ore contains about two percent pure metal. The ore is enriched by flotation, gravity, electromagnetic or magnetic separation. After enrichment, a tungsten concentrate is formed, which contains about 65 percent of tungsten oxide (6). In addition to metal, such concentrates contain impurities of sulfur, copper, phosphorus, arsenic, bismuth, antimony. How much does such a tungsten cost? The price per kg is about a thousand rubles. To make a tungsten powder, it is necessary to restore its anhydride with carbon or hydrogen.

In general, the hydrogenation method is used, since carbon adds brittleness to the metal, negatively affects its workability. For the production of tungsten powder, special methods are used that allow analyzing the composition, grain size, and the composition of the granules formed.

Compact hydrogen, mainly in the form of bars or bars, is used as blanks in the manufacture of semi-finished products such as tape and wire.

Currently, two methods are used to create compact tungsten. The first method involves the use of powder metallurgy. The second method allows the use of arc electric furnaces, involving the use of consumable electrodes.

The most common types of products produced from metallic tungsten and of particular importance are tungsten rods. By forging they are obtained from the staffs on a special forging machine. Apply ready products in various industries of modern industry. For example, it is from them that welding non-consumable electrodes are produced. In addition, tungsten rods are used in the construction of heaters. They are in demand in gas-discharge devices, light bulbs.