What is the density of tungsten? What is its application based on? We will look for answers to the questions posed together.
The situation in the PS
This chemical element is located in the sixth group of the periodic system. Its serial number 74, the value of the relative atomic mass of 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.
Opening item
This chemical element was discovered in the late 18th century. K. Scheele managed to isolate it from a mineral in which the metal was contained in the form of oxide. For a long time, tungsten had virtually no industrial use, was not in demand. Only in the mid-19th century did metal begin to be used as an additive in the manufacture of durable steel.
Content in nature
In the earth's crust, this element is in small quantities. It is not found in free form, it is located only in the form of minerals. On an industrial scale, its oxides are used.
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 indicator of 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 pretreatment. Given the density of tungsten at 20 s 19.3 g / cm3, it can be brought to the state of a single-crystal fiber. This property is used in the manufacture of wire from it. At room temperature, tungsten has little ductility.
Tungsten Features
The significant density of tungsten gives this metal certain properties. It has a fairly 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, and instability to oxidation by atmospheric oxygen at low temperatures.
In terms of external characteristics, tungsten resembles steel. It is used for the manufacture of alloys characterized by high strength. Tungsten processing is carried out only at elevated temperatures.
Tungsten brands
Not only the density of tungsten, but also the additives used in metallurgy are reflected in the brand of this metal. For example, VA involves a mixture of tungsten with aluminum and silicon. The resulting grade is characterized by an increased temperature of initial recrystallization, strength after annealing.
VL involves the addition of lanthanum oxide to tungsten as an additive, which increases the emission properties of the metal.
MV is an alloy of tungsten and molybdenum. Such a composition increases strength, preserves the ductility of the metal after annealing.
Scope of use of tungsten
The unique properties of this metal determine its application. 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 it that is used as the main component (alloying element) in the production of high-speed steels. The average tungsten content is from nine to twenty percent. In addition, it is part of tool steels.
Such forks of steel are used for the manufacture of mills, drills, punches, dies. For example, P6M5 high-speed steels indicate that the steel is alloyed with cobalt and molybdenum. In addition, tungsten is contained in magnetic steels , which are divided into tungsten-cobalt and tungsten species.
In life, tungsten in its pure form is practically not in demand. Tungsten carbide is a compound of this metal with carbon. The compound is characterized by high hardness, refractoriness, and also wear resistance. Based on tungsten carbide, instrumental productive hard alloys are made containing about 90 percent tungsten and about 10 percent cobalt. From hard alloys create the cutting parts of drilling and cutting tools.
Varieties of tungsten-based steels
Wear-resistant and heat-resistant alloys are based on the refractoriness of tungsten. Compounds of tungsten with chromium and cobalt, which are called stellites, are common in industry. They are deposited on the wearing parts of parts of industrial machines by surfacing.
“Heavy” and contact alloys are mixtures of tungsten with silver or with copper. They are considered quite effective contact materials, therefore, they are used for the production of working parts for circuit breakers, electrodes for spot welding, as well as the manufacture of switches.
In the form of wire, forged products, tungsten tapes are used in radio engineering, in the manufacture of electric lamps, as well as in X-ray engineering. It is this metal that is considered the best material for creating spirals and filaments.
Tungsten rods and wire are necessary for the manufacture of electric heaters for high-temperature furnaces. Tungsten-based heaters are capable of operating in an atmosphere of inert gas, hydrogen, and also in vacuum.
One of the most important industries using tungsten is welding. From it create electrodes that are used for arc welding. The resulting electrodes are considered non-consumable.
Obtaining refractory metal
How much is tungsten? The price per kg is in the range from 900 to 1200 rubles. It belongs to the group of rare metal elements. In addition to tungsten, rubidium and molybdenum are also included here. Rare metals have a small scale of use, given their insignificant content in the earth's crust. None of these metals can be obtained by direct reduction from raw materials. For starters, raw materials are processed into various chemicals. It should be noted that special additional ore dressing is also carried out before their full processing.
Three stages are distinguished in the technological chain for producing rare tungsten. First, ore decomposition is carried out, separating the recoverable metal from the mass of raw materials, as well as its concentration in the precipitate or in solution. Next, the production of chemically pure compounds is carried out, the isolation, as well as the purification of the chemical substance, is carried out. At the third stage, metal is extracted from the oxide purified from impurities.
In the manufacture of tungsten, tungsten acts as a feedstock. Such ore contains about two percent of pure metal. Ore dressing is carried out 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 is such a tungsten? The price per kg is about a thousand rubles. To make tungsten powder, it is necessary to restore its anhydride with carbon or hydrogen.
The hydrogenation method is mainly used, since carbon adds brittleness to the metal and negatively affects its machinability. For the manufacture of tungsten powder, special methods are used that allow you to analyze the composition, grain size, as well as the composition of the formed granules.
Compact hydrogen, mainly in the form of ingots or billets, is used as billets in the manufacture of semi-finished products such as tape, wire.
Currently, two methods of creating compact tungsten are used. The first method involves the use of powder metallurgy. The second method allows the use of electric arc furnaces, involving the use of consumable electrodes.
The most common types of products created from tungsten metal and of particular importance are tungsten rods. By forging they are obtained from staffs on a special forging machine. Apply finished products in various sectors of modern industry. For example, it is from them that welding non-consumable electrodes are obtained. In addition, tungsten rods are also used to create heaters. They are in demand in gas-discharge devices, electric lamps.