In the article “Wolfram. Properties, application, production, products” discusses in detail the refractory metal tungsten. The properties of tungsten are described, the areas of its application are indicated. Various grades of tungsten are also listed with their features.

The article covers the process of tungsten production from the stage of ore enrichment to the stage of obtaining blanks in the form of bars and ingots. Characteristic features of each stage are noted.

Particular attention in the article is given to products (wire, rods, sheets, etc.). The processes of manufacturing one or another product from tungsten, its characteristic features and applications are described.

Chapter 1. Tungsten. Properties and applications of tungsten

Tungsten (denoted by W) is a chemical element of group VI of the 6th period of the D.I. table. Mendeleev, has number 74; light gray transition metal. The most refractory metal, has a melting point t pl \u003d 3380 ° C. From the point of view of the application of tungsten metal, its most important properties are density, melting point, electrical resistance, coefficient of linear expansion.

§one. Properties of tungsten

Property	Meaning
Physical properties
atomic number	74
Atomic mass, a.m.u. (g/mol)	183,84
Atomic diameter, nm	0,274
Density, g / cm 3	19,3
Melting point, °С	3380
Boiling point, °С	5900
Specific heat capacity, J/(g K)	0,147
Thermal conductivity, W/(m K)	129
Electrical resistance, µOhm cm	5,5
Coefficient of linear thermal expansion, 10 -6 m/mK	4,32
Mechanical properties
Young's modulus, GPa	415,0
Shear modulus, GPa	151,0
Poisson's ratio	0,29
Ultimate strength σ B , MPa	800-1100
Relative elongation δ, %	0

The metal has a very high boiling point (5900 °C) and a very low evaporation rate even at a temperature of 2000 °C. The electrical conductivity of tungsten is almost three times lower than that of copper. The properties that limit the scope of tungsten include high density, high tendency to brittleness at low temperatures, low resistance to oxidation at low temperatures.

In appearance, tungsten is similar to steel. It is used to create alloys with high strength. Processing (forging, rolling and drawing) tungsten lends itself only when heated. The heating temperature depends on the type of processing. For example, forging bars is carried out by heating the workpiece to 1450-1500 °C.

§2. Tungsten grades

Tungsten brand	Brand characteristic	The purpose of the introduction of the additive
HF	Tungsten pure (no additives)	-
VA	Tungsten with silicon-alkali and aluminum additives	Increase in primary recrystallization temperature, strength after annealing, dimensional stability at high temperatures
VM	Tungsten with silicon-alkali and thorium additives	Increasing the recrystallization temperature and increasing the strength of tungsten at high temperatures
WT	Tungsten doped with thorium oxide
IN AND	Tungsten with yttrium oxide additive	Increasing the emission properties of tungsten
VL	Tungsten with lanthanum oxide additive	Increasing the emission properties of tungsten
BP	Alloy of tungsten and rhenium	An increase in the plasticity of tungsten after high-temperature processing, an increase in the temperature of primary recrystallization, strength at high temperatures, electrical resistivity, etc.
VRN	Tungsten without additive, in which a high content of impurities is allowed	-
MV	Alloys of molybdenum and tungsten	Increasing the strength of molybdenum while maintaining ductility after annealing

§3. Applications of tungsten

Tungsten has been widely used due to its unique properties. In industry, tungsten is used as a pure metal and in a number of alloys.

The main areas of application of tungsten
1. Special steels
Tungsten is used as one of the main components or an alloying element in the production of high-speed steels (contain 9-24% tungsten W), as well as tool steels (0.8-1.2% tungsten W - tungsten tool steels; 2-2.7 % tungsten W - chromium tungsten silicon tool steels (also contain chromium Cr and silicon Si); 2-9% tungsten W - chromium tungsten tool steels (also contain chromium Cr); 0.5-1.6% tungsten W - chromium tungsten manganese tool steels (also contain chromium Cr and manganese Mn). Drills, milling cutters, punches, dies, etc. are made from the listed steels. Examples of high-speed steels include R6M5, R6M5K5, R6M5F3. The letter “P” means that the steel is high-speed, the letters “M” and "K" - that the steel is alloyed with molybdenum and cobalt, respectively.Tungsten is also part of magnetic steels, which are divided into tungsten and tungsten-cobalt.

2. Hard alloys based on tungsten carbide
Tungsten carbide (WC, W 2 C) - a compound of tungsten with carbon (see). It has high hardness, wear resistance and refractoriness. On its basis, the most productive tool hard alloys are created, which contain 85-95% WC and 5-14% Co. Working parts of cutting and drilling tools are made from hard alloys.

3. Heat-resistant and wear-resistant alloys
These alloys use the refractoriness of tungsten. The most common alloys of tungsten with cobalt and chromium - stellites (3-5% W, 25-35% Cr, 45-65% Co). They are usually applied with the help of surfacing to the surfaces of heavily worn machine parts.

4. Contact alloys and “heavy alloys”
These alloys include tungsten-copper and tungsten-silver alloys. These are sufficiently effective contact materials for the manufacture of working parts of knife switches, switches, electrodes for spot welding, etc.

5. Electrovacuum and electric lighting equipment
Tungsten in the form of wire, tape and various forged parts is used in the production of electric lamps, radio electronics and X-ray technology. Tungsten is the best material for filaments and filaments. Tungsten wire and rods serve as electric heaters for high-temperature furnaces (up to ~3000 °C). Tungsten heaters operate in an atmosphere of hydrogen, inert gas or vacuum.

6. Welding electrodes
A very important area of ​​application of tungsten is welding. Tungsten is used to make electrodes for arc welding (see). Tungsten electrodes are non-consumable.

Chapter 2 Tungsten Production

§one. The process of obtaining refractory metal tungsten

Tungsten is usually referred to a wide group of rare metals. In addition to this metal, this group includes molybdenum, rubidium and others. Rare metals are characterized by a relatively small scale of production and consumption, as well as a low prevalence in the earth's crust. Not a single rare metal is obtained by direct reduction from raw materials. First, raw materials are processed into chemical compounds. In addition, all rare metal ores undergo additional enrichment before processing.

In the process of obtaining a rare metal, three main stages can be distinguished:

• The decomposition of ore material is the separation of the extracted metal from the bulk of the processed raw material and its concentration in solution or sediment.
• Obtaining pure chemical compounds - isolation and purification of a chemical compound.
• Isolation of the metal from the resulting compound - obtaining pure rare metals.

The process of obtaining tungsten also has several stages. The feedstock are two minerals - wolframite (Fe, Mn)WO 4 and scheelite CaWO 4 . Rich tungsten ores usually contain 0.2 - 2% tungsten.

• Enrichment of tungsten ore. It is produced by gravity, flotation, magnetic or electrostatic separation. As a result of enrichment, a tungsten concentrate is obtained containing 55 - 65% of tungsten anhydride (trioxide) WO 3 . The content of impurities - phosphorus, sulfur, arsenic, tin, copper, antimony and bismuth - is controlled in tungsten concentrates.
• Obtaining tungsten trioxide (anhydride) WO 3 , which serves as a feedstock for the production of metallic tungsten or its carbide. To do this, it is necessary to perform a number of actions, such as decomposition of concentrates, leaching of an alloy or sinter, obtaining technical tungstic acid, etc. As a result, a product containing 99.90 - 99.95% WO 3 should be obtained.
• Obtaining tungsten powder. Pure metal in powder form can be obtained from tungsten anhydride WO 3 . To do this, carry out the process of reduction of anhydride with hydrogen or carbon. Carbon reduction is used less often, since in this process WO 3 is saturated with carbides, which makes the metal more brittle and impairs machinability. When obtaining tungsten powder, special methods are used to control its chemical composition, grain size and shape, and particle size distribution. For example, a rapid rise in temperature and a low hydrogen supply rate contribute to an increase in the powder particle size.
• Obtaining compact tungsten. Compact tungsten, usually in the form of rods or ingots, is a blank for the production of semi-finished products, such as wire, rod, strip, and so on.

§2. Obtaining compact tungsten

There are two ways to obtain compact tungsten. The first is the application of powder metallurgy methods. The second is by melting in electric arc furnaces with a consumable electrode.

Powder Metallurgy Methods
This method of obtaining malleable tungsten is the most common, as it allows a more even distribution of additives that give tungsten special properties (heat resistance, emission properties, and others).

The process of obtaining compact tungsten by this method consists of several stages:

• pressing rods from metal powder;
• low-temperature (preliminary) sintering of blanks;
• sintering (welding) of blanks;
• processing of blanks in order to obtain semi-finished products - tungsten wire, tape, tungsten rods; Usually blanks are processed under pressure (forging) or subjected to machining by cutting (for example, grinding, polishing).

There are special requirements for tungsten powder. Use powders reduced only by hydrogen and containing no more than 0.05% impurities.

Using the described method of powder metallurgy, tungsten rods of square section from 8x8 to 40x40 mm and a length of 280-650 mm are obtained. At room temperature, they have good strength, but are very brittle. It is worth noting that strength and brittleness (opposite property - ductility) belong to different groups of properties. Strength is a mechanical property of a material, ductility is a technological property. Plasticity determines the suitability of a material for forging. If the material is difficult to forge, then it is brittle. To improve ductility, tungsten rods are forged in a heated state.

However, the method described above cannot produce large-sized workpieces of large mass, which is a significant limitation. To obtain large-sized blanks, the mass of which reaches several hundred kilograms, hydrostatic pressing is used. This method makes it possible to obtain blanks of cylindrical and rectangular cross-section, pipes and other products of complex shape. At the same time, they have a uniform density, do not contain cracks and other defects.

Fuse
Melting is used to obtain compact tungsten in the form of large billets (from 200 to 3000 kg) intended for rolling, pipe drawing, and the production of products by casting. Melting is carried out in electric arc furnaces with a consumable electrode and/or electron beam melting.

In arc melting, packages of sintered rods or hydrostatically pressed sintered blanks serve as electrodes. Melting is carried out in a vacuum or a rarefied hydrogen atmosphere. The result is tungsten ingots. Tungsten ingots have a coarse-grained structure and increased brittleness, which is caused by a high content of impurities.

To reduce the content of impurities, tungsten is initially melted in an electron beam furnace. But after this type of melting, tungsten also has a coarse-grained structure. Therefore, then, in order to reduce the grain size, the resulting ingots are melted in an electric arc furnace, adding small amounts of zirconium or niobium carbides, as well as alloying elements to impart special properties.

To obtain fine-grained tungsten ingots, as well as to manufacture parts by casting, arc skull melting is used with pouring metal into a mold.

Chapter 3. Products from tungsten. Rods, wire, strips, powder

§one. Tungsten rods

Production
Tungsten rods are one of the most common types of tungsten refractory metal products. The starting material for the production of bars is a rod.

To obtain tungsten rods, the rod is forged on a rotary forging machine. Forging is carried out in a heated state, since tungsten is very brittle at room temperature. There are several stages of forging. At each next stage, bars of a smaller diameter are obtained than at the previous one.

During the first forging, tungsten rods with a diameter of up to 7 mm can be obtained (provided that the rod has a side length of 10-15 cm). Forging is carried out at a billet temperature of 1450-1500 °C. Molybdenum is commonly used as the heater material. After the second forging, bars with a diameter of up to 4.5 mm are obtained. It is produced at a rod temperature of 1300-1250 °C. With further forging, tungsten rods with a diameter of up to 2.75 mm are obtained. It should be noted that tungsten rods of grades VT, VL and VI are produced at a higher temperature than rods of grades VA and VCh.

If tungsten ingots, which are obtained by smelting, are used as the initial billet, then hot forging is not carried out. This is due to the fact that these ingots have a rough macrocrystalline structure, and their hot forging can lead to cracking and failure.

In this case, the tungsten ingots are subjected to double hot pressing (the degree of deformation is about 90%). The first pressing is carried out at a temperature of 1800-1900 °C, the second - 1350-1500 °C. The blanks are then hot forged to produce tungsten rods.

Application
Tungsten rods are widely used in various industries. One of the most common applications is non-consumable welding electrodes. For such purposes, tungsten rods of grades VT, VI, VL are suitable. Also, tungsten rods of grades VA, BP, MV are used as heaters. Tungsten heaters operate in furnaces up to 3000 °C in an atmosphere of hydrogen, an inert gas, or in a vacuum. Tungsten rods can serve as cathodes for radio tubes, electronic and gas-discharge devices.

§2. Tungsten electrodes

arc welding
Welding electrodes are one of the most important components needed for welding. They are most widely used in arc welding. It belongs to the thermal class of welding, in which melting is carried out due to thermal energy. Arc welding (manual, semi-automatic and automatic) is the most common welding process. Thermal energy is created by a voltaic arc that burns between the electrode and the product (part, workpiece). Arc - a powerful stable electric discharge in an ionized atmosphere of gases, metal vapors. The electrode delivers an electric current to the welding site to create an arc.

Welding electrodes
Welding electrode - a wire rod coated (or uncoated). There are a wide variety of electrodes for welding. They differ in chemical composition, length, diameter, a certain type of electrode is suitable for welding certain metals and alloys, etc. etc. The division of welding electrodes into consumable and non-consumable is one of the most important types of their classification.

Consumable welding electrodes are melted during the welding process, their metal, together with the molten metal of the welded part, goes to replenish the weld pool. Such electrodes are made of steel and copper.

Non-consumable electrodes do not melt during welding. This type includes carbon and tungsten electrodes. When welding using non-consumable tungsten electrodes, it is necessary to supply filler material (usually a welding wire or rod), which melts and forms a weld pool together with the molten material of the welded part.

Also, electrodes for welding are coated and uncoated. Coverage plays an important role. Its components can ensure the production of weld metal of a given composition and properties, stable arc burning, protection of molten metal from air exposure. Accordingly, the components of the coating can be alloying, stabilizing, gas-forming, slag-forming, deoxidizing, and the coating itself can be acidic, rutile, basic or cellulose.

Welding tungsten electrodes
As noted earlier, tungsten electrodes are non-consumable and are used in welding together with filler wire. These electrodes are mainly used for welding non-ferrous metals and their alloys (tungsten electrode with zirconium additive), high-alloy steels (tungsten electrode with EWT thorium additive), and the tungsten electrode is well suited for obtaining a weld of increased strength, and the parts to be welded can be of different chemical composition.

Quite common is welding using tungsten electrodes in argon. This environment has a positive effect on the welding process and the quality of the weld. Tungsten electrodes can be made from pure tungsten or contain various additives that improve the quality of the welding process and the weld. A feature of non-consumable welding electrodes made of pure tungsten (for example, a tungsten electrode of the EHF brand) is not very good arc ignition.

The ignition of the arc takes place in three stages:

• short circuit of the electrode to the workpiece;
• removal of the electrode to a small distance;
• the occurrence of a stable arc discharge.

Zirconium is added to tungsten electrodes to improve arc ignition and achieve high arc stability during welding. Thoriation (tungsten electrode EVT-15) also improves arc ignition and increases the service life of welding electrodes. The addition of yttrium to tungsten electrodes (tungsten electrode EVI-1, EVI-2, EVI-3) makes it possible to use them in various current media. For example, there may be an AC or DC arc. In the first case, the welding arc is powered by an alternating current source. Distinguish between single-phase and three-phase arc power supply. In the second - from a direct current source.

Argon arc welding (Arc welding with a non-consumable tungsten electrode in an argon environment) This type of welding has proven itself when welding non-ferrous metals such as molybdenum, titanium, nickel, as well as high-alloy steels. This is a type of arc welding where the source of the heat required to create the weld pool is an electric current. In this type of argon arc welding, the main elements are a tungsten electrode and an inert gas argon. Argon is supplied to the tungsten electrode during welding and protects it, the arc zone and the weld pool from the atmospheric gas mixture (nitrogen, hydrogen, carbon dioxide). This protection greatly improves the quality characteristics of the weld, and also protects the welding tungsten electrodes from rapid combustion in the air. Argon gas can be used when welding a large number of metals and alloys, as it is inert.

Standards for tungsten electrodes
In Russia, non-consumable tungsten electrodes are produced in accordance with the requirements of standards and specifications. Among them: GOST 23949-80“Tungsten electrodes for welding, non-consumable. Specifications”; TU 48-19-27-88“Tungsten lanthanated in the form of bars. Specifications”; TU 48-19-221-83“Rods made of yttrated tungsten grade SVI-1. Specifications”; TU 48-19-527-83“Tungsten welding non-consumable electrodes EVCh and EVL-2. Specifications”.

§3. Tungsten wire

Production
Tungsten wire is one of the most common types of products made from this refractory metal. The starting material for its manufacture are forged tungsten rods with a diameter of 2.75 mm.

Wire drawing is carried out at a temperature of 1000 °C at the beginning of the process and 400-600 °C at the end. In this case, not only the wire is heated, but also the die. Heating is carried out by a gas burner flame or an electric heater.

Wire drawing with a diameter of up to 1.26 mm is carried out on a straight chain drawing bench, within a diameter of 1.25-0.5 mm - on a block mill with a coil diameter of ~ 1000 mm, a diameter of 0.5-0.25 - on single drawing machines .

As a result of forging and drawing, the workpiece structure becomes fibrous, which consists of crystal fragments elongated along the processing axis. This structure leads to a sharp increase in the strength of the tungsten wire.

After drawing, the tungsten wire is coated with graphite grease. The surface of the wire must be cleaned. Cleaning is carried out by annealing, chemical or electrolytic etching, electrolytic polishing. Polishing can increase the mechanical strength of tungsten wire by 20-25%.

Application
Tungsten wire is used for the manufacture of resistance elements in heating furnaces operating in an atmosphere of hydrogen, neutral gas or vacuum at temperatures up to 3000 °C. Also, tungsten wire is used for the production of thermocouples. For this, a tungsten-rhenium alloy with 5% rhenium and a tungsten-rhenium alloy with 20% rhenium are used ( VR 5/20).

AT GOST 18903-73“Tungsten wire. Assortment” indicates the areas of application of wire grades VA, VM, VRN, VT-7, VT-10, VT-15. VA tungsten wire, depending on the group, surface condition and metal, diameter, is used for the manufacture of spirals of incandescent lamps and other light sources, spiral cathodes and heaters for electronic devices, springs for semiconductor devices, loop heaters, non-spiral cathodes, grids, springs for electronic devices. VRN grade wire is used in the production of bushings, traverses and other parts of devices that do not require the use of tungsten with special additives.

§4. Tungsten Powder

Pure tungsten powder serves as the raw material for the production of compact tungsten (see). Tungsten carbide WC, which also looks like a powder, is used to make hard alloys.

Depending on the purpose, tungsten powders are distinguished by the average particle size, a set of grains, and other parameters.

The main impurity in tungsten powders is oxygen (0.05 - 0.3%). Metal impurities are contained in tungsten powders in very small quantities. Often, additives from other metals are introduced into tungsten powders, which improve certain properties of the final product. Aluminum, thorium, lanthanum and others are often used as additives.

VA tungsten powder, which is used for the manufacture of wire, contains evenly distributed silicon-alkali and aluminum additives (0.32% K 2 O; 0.45% SiO 2; 0.03% Al 2 O 3), powder from refractory metal tungsten grade VT - thorium oxide additive (0.7 - 5%), VL - lanthanum oxide additive (~ 1% La 2 O 3), VI - yttrium oxide additive (~ 3% Y 2 O 3), VM - silica and thorium additives ( 0.32% K 2 O, 0.45% SiO 2 , 0.25% ThO 2).

§5. Tungsten strips (sheets, tapes, foils, plates)

Production
As a rule, flat products from tungsten - sheets, strips, plates, foil - are obtained using two operations - flat forging and rolling. Tungsten rods of various sizes are used as blanks.

First, the tungsten rods are flat forged with a pneumatic hammer. Forging is carried out at a temperature of 1500-1700 °C, which decreases to 1200-1300 °C as deformation proceeds. The forging operation continues until a forging is obtained with a thickness of 8-10 mm (with a rod section of 25x25 mm) or 4-5 mm (with a rod section of 12x12 mm).

Then the resulting forgings are subjected to rolling on rolling mills. At the beginning of the rolling process, the workpieces are heated to 1300-1400 °C, then the temperature is lowered to 1000-1200 °C. Hot rolling produces tungsten sheets, strips and plates up to 0.6 mm thick. To obtain sheets, strips and plates of a smaller size, cold rolling is carried out. To obtain thin sheets of tungsten with a thickness of up to 0.125 mm and tape (foil) with a thickness of 0.02-0.03 mm, rolling in packages is used. The package consists of several tungsten strips of equal thickness and thicker molybdenum plates that lie on top of the tungsten strips. Molybdenum plates are more ductile and deform faster than tungsten plates. As a result, during rolling, they become thinner than tungsten strips. After one or more transitions, the molybdenum plates have to be replaced with new ones so that the thickness of the package remains approximately constant. It should be noted that the purpose of this process is the manufacture of a thin tungsten tape (foil). Molybdenum plates here are a consumable material that is necessary for the implementation of rolling in packages.

Tungsten ingots, which are obtained by smelting, can also serve as blanks for tungsten tape, plates and sheets (see). Ingots are pre-pressed. Rectangular blanks 20-25 mm thick and 50-60 mm wide are obtained by pressing from ingots with a diameter of 70-80 mm. Then the blanks are deformed on two-roll presses.

Tungsten sheets V-MP
V-MP tungsten sheets are widely used in industry. They are made from tungsten powder grades PV1 and PV2, containing 99.98% W. V-MP sheets and plates must have a thickness of 0.5-45 mm, cut edges. Sheets can be machined according to customer requirements. GOST 23922-79“V-MP tungsten sheets. Specifications”.

Application
Due to the high heat resistance, tungsten sheets, like other products made from this refractory metal, are used in conditions of extremely high temperatures. Various accessories for high-temperature furnaces are made from tungsten sheets - heat shields, stands and other fastening elements. Sputtered tungsten targets, which are made in the form of plates, are used for thin barrier films in the metallization of semiconductor components of integrated circuits. In the nuclear power industry, tungsten sheets are used as shields to attenuate the flow of radioactive radiation.

§6. Alloys of tungsten with rhenium

A separate paragraph should include tungsten-rhenium alloys and products made from these alloys. Alloys of grades BP5 and BP20 will be considered in more detail here.

Alloys of these two metals are heat-resistant. Doping tungsten with other metals lowers its melting point. But when alloying with a refractory metal, the melting point of the alloy does not decrease so significantly. Tungsten (W) and rhenium (Re) are refractory metals.

When rhenium is used as an additive, a “rhenium effect” is observed. 5% rhenium increases the heat resistance and ductility of tungsten. At 20-30% rhenium content, an optimal combination of strength and ductility with high manufacturability is observed. Also, the advantages of tungsten-rhenium alloys include a low evaporation rate at operating temperatures and high electrical resistance.

Alloys of tungsten with rhenium, like compact tungsten, are obtained by powder metallurgy and smelting.

An interesting area of ​​application for these alloys is temperature measurement. Tungsten-rhenium wire VR5 (5% Re, the rest - W) and VR20 (20% Re, the rest - W) are used for the manufacture of high-temperature thermocouples.

The main advantage of such thermocouples is the range of measured temperatures. Insofar as alloys VR 5/20 are heat-resistant, then with the help of thermocouples made of the appropriate wire, it is possible to measure temperatures above 2000 °C. However, thermocouples of this type must be in an inert environment.

Most often, for the manufacture of thermocouples, tungsten-rhenium thermoelectrode wire VR5, VR20 Ø 0.2 is used; 0.35; 0.5 mm.

§7. Tungsten carbides

Very important from a practical point of view are compounds of tungsten with carbon - tungsten carbides. Tungsten forms two carbides - W 2 C and WC. These carbides differ in solubility in carbides of other refractory metals and chemical behavior in various acids. Tungsten carbides, like carbides of other refractory metals, have metallic conductivity and a positive coefficient of electrical resistance. The refractoriness and high hardness of carbides are due to strong interatomic bonds in their crystals. Moreover, the high hardness of WC carbide is retained at elevated temperatures.

The most common method for obtaining tungsten carbides WC and W 2 C is the calcination of a mixture of powdered tungsten with soot in the temperature range of 1000-1500 °C.

Tungsten carbides WC and W 2 C are mainly used for the manufacture of hard alloys.

Carbide
There are 2 groups of hard alloys based on tungsten carbide:

• cast hard alloys (often referred to as cast tungsten carbides);
• sintered hard alloys.

Cast Carbide obtained by casting. To obtain an alloy, powdered tungsten, carbide with a lack of carbon (up to 3% C) or a mixture of WC + W, in which the carbon content does not exceed 3%, usually come from. The fine-grained structure of this type of carbides provides higher hardness and wear resistance of the alloy. However, cast alloys are quite brittle. This circumstance limits their application. Mainly, cast hard alloys are used in the manufacture of drilling tools and drawing dies for fine wire drawing.

Sintered Carbide combine tungsten monocarbide WC and a cementing bond metal, which is usually cobalt, less often nickel. Such alloys can only be obtained by powder metallurgy. Tungsten carbide powder and cobalt or nickel powder are mixed, pressed into products of the required shape, and then sintered at temperatures close to the melting point of the cementing metal. In addition to high hardness and wear resistance, these alloys have good strength. Sintered hard alloys are the most productive modern tool materials for metal cutting. They are also used for the manufacture of dies, dies, drilling tools. Among the hard alloys, for the production of which tungsten carbide is used, it is worth highlighting the alloys of the VK group - tungsten-cobalt hard alloys. Widespread in industry VK8 alloys and VK6. They are used to make cutters, drills, cutters, as well as other cutting and drilling tools.

Conclusion

This article discusses various aspects related to TUNGSTEN refractory metal - properties, applications, production, products.

As described in the article, the process of obtaining this metal consists of many stages and is quite laborious. The authors tried to highlight the most significant stages of tungsten production and pay attention to important features.

A review of the properties and applications of tungsten shows that it is a very important material, without which it is simply impossible to do without in some industries. It has unique properties that in some situations cannot be obtained by using other materials.

An overview of the tungsten products produced by the industry - wire, rods, sheets, powder - allows a better understanding of their features, important properties and specific applications.

Properties of tungsten

Tungsten- it's metal. It is not in the water of the seas, it is not in the air, and in the earth's crust it is only 0.0055%. Such tungsten, element, standing at the 74th position in . For industry, it was "opened" by the World Exhibition in the French capital. It took place in 1900. The exhibition featured tungsten steel.

The composition was so hard that it could cut through any material. remained "invincible" even at temperatures of thousands of degrees, therefore it was called red-resistant. Manufacturers from different countries who visited the exhibition took the development into service. The production of alloyed steel has acquired a global scale.

Interestingly, the element itself was discovered back in the 18th century. In 1781, the Swede Scheeler experimented with the mineral tungsten. The chemist decided to put it in nitric acid. In the decomposition products, the scientist discovered an unknown gray metal with a silvery sheen. The mineral on which the experiments were carried out was later renamed scheelite, and the new element called tungsten.

However, it took a lot of time to study its properties, and therefore a worthy application for the metal was found much later. The name was chosen immediately. Word tungsten existed before. The Spaniards called this one of the minerals found in the deposits of the country.

The composition of the stone, indeed, included element No. 74. Externally, the metal is porous, as if foamed. So another analogy came in handy. In German, tungsten literally means "wolf foam".

The melting point of the metal competes with hydrogen, and it is the most temperature-resistant element. Therefore, and install softening index of tungsten could not for a hundred years. There were no furnaces capable of heating up to several thousand degrees.

When the “benefit” of the silver-gray element was “seen through”, it began to be mined on an industrial scale. For the 1900 exhibition, the metal was extracted the old fashioned way with nitric acid. However, tungsten is still mined this way.

Tungsten mining

Most often, trioxide is first obtained from ore waste. It is processed at 700 degrees, obtaining pure metal in the form of dust. To soften the particles, one has to resort just to hydrogen. In it tungsten is melted down at three thousand degrees Celsius.

The alloy goes to cutters, pipe cutters, cutters. for metal processing with application of tungsten improve the accuracy of parts manufacturing. When exposed to metal surfaces, friction is high, which means that the working surfaces are very hot. Cutting and polishing machines without element No. 74 can melt themselves. This makes the cut inaccurate, imperfect.

Tungsten is not only difficult to melt, but also to process. In the hardness scale, the metal occupies the ninth position. Corundum has the same number of points, from the crumbs of which, for example, a knife is made. Only diamond is harder. Therefore, with its help, tungsten is processed.

Application of tungsten

The "steadfastness" of the 74th element attracts. Products made of alloys with gray-silver metal cannot be scratched, bent, broken, unless, of course, they are scraped over the surface or with the same diamonds.

Tungsten jewelry has another indisputable plus. They do not cause allergic reactions, unlike gold, silver, platinum and, even more so, their alloys with or. For jewelry, tungsten carbide is used, that is, its combination with carbon.

It is recognized as the hardest alloy in the history of mankind. Its polished surface perfectly reflects light. Jewelers call it the "gray mirror".

By the way, jewelry craftsmen turned their attention to tungsten after the cores of bullets, shells and plates for bulletproof vests began to be made from this substance in the middle of the 20th century.

Customers' complaints about the fragility of the highest standards and silver jewelry made jewelers think about a new element and try to apply it in their industry. In addition, prices began to fluctuate. Tungsten has become an alternative to the yellow metal, which is no longer perceived as an investment.

Being a precious metal tungsten worth a lot of money. For a kilogram they ask for at least 50 dollars in the wholesale market. The world industry consumes 30 thousand tons of element No. 74 per year. More than 90% is absorbed by the metallurgical industry.

Only made from tungsten containers for storage of nuclear waste. Metal does not transmit destructive rays. A rare element is added to alloys for the manufacture of surgical instruments.

What is not used for metallurgical purposes is taken by the chemical industry. Tungsten compounds with phosphorus, for example, are the basis of varnishes and paints. They do not collapse, do not fade from the sun's rays.

BUT sodium tungstate solution resistant to moisture and fire. It becomes clear what impregnated waterproof and fireproof fabrics for suits of divers and firefighters.

Tungsten deposits

There are several deposits of tungsten in Russia. They are located in Altai, the Far East, the North Caucasus, Chukotka and Buryatia. Outside the country, the metal is mined in Australia, the USA, Bolivia, Portugal, South Korea and China.

There is even a legend in the Celestial Empire about a young explorer who came to China to look for a tin stone. The student settled in one of the houses in Beijing.

After a fruitless search, the guy liked to listen to the stories of the owner's daughter. One evening she told the story of the dark stones from which the home stove was built. It turned out that the blocks were falling from the cliff into the backyard of the building. So, the student did not find, but found tungsten.

Chemistry

Element No. 74 tungsten is usually classified as a rare metal: its content in the earth's crust is estimated at 0.0055%; it is not found in sea water, it could not be detected in the solar spectrum. However, in terms of popularity, it can compete with many by no means rare metals, and its minerals were known long before the discovery of the element itself. So, back in the 17th century. in many European countries they knew "tungsten" and "tungsten" - that was the name of the most common tungsten minerals at that time - wolframite and scheelite. And elementary tungsten was discovered in the last quarter of the 18th century.

Tungsten ore

Very soon, this metal gained practical importance - as an alloying additive. And after the World Exhibition of 1900 in Paris, where samples of high-speed tungsten steel were demonstrated, element No. 74 began to be used by metallurgists in all more or less industrialized countries. The main feature of tungsten as an alloying additive is that it imparts red hardness to steel - it allows you to maintain hardness and strength at high temperatures. Moreover, most steels lose their hardness when cooled in air (after holding at a temperature close to the red heat temperature). But tungsten - no.
The tool, made of tungsten steel, withstands the enormous speeds of the most intensive metalworking processes. The cutting speed of such a tool is measured in tens of meters per second.
Modern high speed steels contain up to 18% tungsten (or tungsten with molybdenum), 2-7% chromium and a small amount of cobalt. They retain their hardness at 700-800 ° C, while ordinary steel begins to soften when heated to only 200 ° C. "Stellites" - alloys have even greater hardness
tungsten and with chromium and cobalt (without iron) and especially tungsten carbides - its compounds with carbon. The “visible” alloy (tungsten carbide, 5-15% cobalt and a small admixture of titanium carbide) is 1.3 times harder than ordinary tungsten steel and retains hardness up to 1000-1100 ° C. Cutters from this alloy can be removed in a minute up to 1500-2000 m of iron shavings. They can quickly and accurately process "capricious" materials: bronze and porcelain, glass and ebonite; at the same time, the tool itself wears out very little.
At the beginning of the XX century. tungsten filament began to be used in electric light bulbs: it allows you to bring the heat up to 2200 ° C and has a high light output. And in this capacity, tungsten is absolutely indispensable to this day. Obviously, this is why the light bulb is called in one popular song "tungsten eye".

Minerals and ores of tungsten

Tungsten occurs in nature mainly in the form of oxidized complex compounds formed by tungsten trioxide WO 3 and oxides of iron and manganese or calcium, and sometimes lead, copper, thorium and rare earth elements. The most common mineral, wolframite, is a solid solution of tungstates (salts of tungstic acid) of iron and manganese (mFeW0 4 *nMnW0 4). This solution is heavy and hard brown or black crystals, depending on which compound predominates in their composition. If there is more pobnerite (manganese compounds), the crystals are black, but if iron-containing ferberite predominates, they are brown. Wolframite is paramagnetic and a good conductor of electricity.
Of the other tungsten minerals, scheelite, calcium tungstate CaW04, is of industrial importance. It forms crystals, shining like glass, of light yellow, sometimes almost white color. Scheelite is non-magnetic, but it has another characteristic feature - the ability to luminesce. When illuminated with ultraviolet rays, it fluoresces bright blue in the dark. The admixture of molybdenum changes the color of the glow of scheelite: it becomes pale blue, and sometimes even cream. This property of scheelite, used in geological exploration, serves as a search feature that allows you to detect mineral deposits.
Deposits of tungsten ores are theologically connected with areas of distribution of granites. The largest foreign deposits of wolframite and scheelite are located in China, Burma, the USA, Bolivia and Portugal. Our country also has significant reserves of tungsten minerals, their main deposits are in the Urals, the Caucasus and Transbaikalia.
Large crystals of wolframite or scheelite are very rare. Usually, tungsten minerals are only interspersed in ancient granitic rocks - the average concentration of tungsten in the end turns out to be 1-2% at best. Therefore, it is very difficult to extract tungsten from ores.

How is tungsten obtained

The first stage is the enrichment of ore, the separation of valuable components from the main mass - waste rock. Concentration methods are common for heavy ores and metals: grinding and flotation followed by magnetic separation (for wolframite ores) and oxidative roasting.
The resulting concentrate is most often sintered with an excess of soda to convert the tungsten into a soluble compound, sodium tungstate. Another way to obtain this substance is by leaching; tungsten is extracted with a soda solution under pressure and at elevated temperature (the process takes place in an autoclave), followed by neutralization and precipitation in the form of artificial scheelite, i.e., calcium tungstate. The desire to get exactly tungstate is explained by the fact that it is relatively simple from it, in just two stages:
CaW0 4 → H 2 W0 4 or (NH 4) 2 W0 4 → WO 3, tungsten oxide purified from most of the impurities can be isolated.
There is another way to obtain tungsten oxide - through chlorides. Tungsten concentrate is treated with gaseous chlorine at elevated temperature. The resulting tungsten chlorides are quite easy to separate from the chlorides of other metals by sublimation, using the temperature difference at which these substances pass into a vapor state. The resulting tungsten chlorides can be converted into oxide, or can be used directly for processing into elemental metal.

The transformation of oxides or chlorides into metal is the next step in the production of tungsten. The best reducing agent for tungsten oxide is hydrogen. When reduced with hydrogen, the purest metallic tungsten is obtained. The reduction process takes place in tube furnaces heated in such a way that, as it moves along the pipe, the “boat” with W0 3 passes through several temperature zones. A stream of dry hydrogen flows towards it. Recovery occurs both in "cold" (450-600 ° C) and in "hot" (750-1100 ° C) zones; in "cold" - to the lowest oxide W0 2, then - to the elemental metal. Depending on the temperature and duration of the reaction in the "hot" zone, the purity and size of the grains of powdered tungsten released on the walls of the "boat" change.
Recovery can take place not only under the action of hydrogen. In practice, coal is often used. The use of a solid reducing agent somewhat simplifies production, but in this case a higher temperature is required - up to 1300-1400 ° C. In addition, coal and the impurities that it always contains react with tungsten, forming carbides and other compounds. This leads to contamination of the metal. Meanwhile, electrical engineering needs very pure tungsten. Only 0.1% iron makes tungsten brittle and unsuitable for making the thinnest wire.
The production of tungsten from chlorides is based on the pyrolysis process. Tungsten forms several compounds with chlorine. With the help of an excess of chlorine, all of them can be converted into the highest chloride - WCl 6, which decomposes into tungsten and chlorine at 1600 ° C. In the presence of hydrogen, this process proceeds already at 1000 ° C.
This is how metal tungsten is obtained, but not compact, but in the form of a powder, which is then pressed in a stream of hydrogen at high temperature. At the first stage of pressing (when heated to 1100–1300°C), a porous brittle ingot is formed. Pressing is continued at an even higher temperature, almost reaching the melting point of tungsten at the end. Under these conditions, the metal gradually becomes solid, acquires a fibrous structure, and with it plasticity and malleability.

Main properties

Tungsten differs from all other metals in its special severity, hardness and refractoriness. The expression "heavy as lead" has long been known. It would be more correct to say: "Heavy, like tungsten." The density of tungsten is almost twice that of lead, more precisely, 1.7 times. At the same time, its atomic mass is slightly lower: 184 versus 207.

In terms of refractoriness and hardness, tungsten and its alloys occupy the highest places among metals. Technically pure tungsten melts at 3410° C, and boils only at 6690° C. Such a temperature is on the surface of the Sun!
And the “king of refractoriness” looks pretty ordinary. The color of tungsten largely depends on the method of obtaining. Fused tungsten is a lustrous gray metal that most closely resembles platinum. Tungsten powder - gray, dark gray and even black (the finer the grain, the darker).

Chemical activity

Natural tungsten consists of five stable isotopes with mass numbers from 180 to 186. In addition, in nuclear reactors, as a result of various nuclear reactions, another 8 radioactive isotopes of tungsten are formed with mass numbers from 176 to 188; they are all relatively short-lived, with half-lives ranging from a few hours to several months.
The seventy-four electrons of the tungsten atom are arranged around the nucleus in such a way that six of them are in outer orbits and can be separated relatively easily. Therefore, the maximum valence of tungsten is six. However, the structure of these outer orbits is special - they consist, as it were, of two “tiers”: four electrons belong to the penultimate level -d, which, therefore, turns out to be less than half filled. (It is known that the number of electrons in a filled level d is equal to ten.) These four electrons (apparently unpaired) can easily form a chemical bond. As for the two “outermost” electrons, it is quite easy to tear them off.
It is the structural features of the electron shell that explain the high chemical activity of tungsten. In compounds, it is not only hexavalent, but also five-, four-, three-, two- and zero-valent. (Only compounds of monovalent tungsten are unknown).
The activity of tungsten is manifested in the fact that it reacts with the vast majority of elements, forming many simple and complex compounds. Even in alloys, tungsten is often chemically bonded. And with oxygen and other oxidizing agents, it interacts more easily than most heavy metals.
The reaction of tungsten with oxygen occurs when heated, especially easily in the presence of water vapor. If tungsten is heated in air, then at 400-500 ° C, a stable lower oxide W0 2 is formed on the metal surface; the entire surface is covered with a brown film. At a higher temperature, the blue intermediate oxide W 4 O 11 is obtained first, and then lemon-yellow tungsten trioxide W0 3, which sublimates at 923 ° C.

Dry fluorine combines with finely ground tungsten even with a slight heating. In this case, WF6 hexafluoride is formed - a substance that melts at 2.5 ° C and boils at 19.5 ° C. A similar compound - WCl 6 - is obtained by reaction with chlorine, but only at 600 ° C. Steel-blue crystals of WCl 6 melt at 275 ° C and boil at 347 ° C. With bromine and iodine, tungsten forms unstable compounds: penta- and dibromide, tetra- and diiodine.
At high temperatures, tungsten combines with sulfur, selenium and tellurium, with nitrogen and boron, with carbon and silicon. Some of these compounds are very hard and have other remarkable properties.
The carbonyl W(CO) 6 is very interesting. Here, tungsten is combined with carbon monoxide and, therefore, has a zero valency. Tungsten carbonyl is unstable; it is obtained under special conditions. At 0°C, it separates from the corresponding solution in the form of colorless crystals, sublimates at 50°C, and completely decomposes at 100°C. But it is this compound that makes it possible to obtain thin and dense coatings from pure tungsten.
Not only tungsten itself, but also many of its compounds are very active. In particular, tungsten oxide WO 3 is polymerizable. As a result, the so-called isopolycompounds and heteropolycompounds are formed: the molecules of the latter can contain more than 50 atoms.

Alloys

With almost all metals, tungsten forms alloys, but it is not so easy to obtain them. The fact is that generally accepted methods of fusion in this case, as a rule, are not applicable. At the melting point of tungsten, most other metals are already converted into gases or highly volatile liquids. Therefore, alloys containing tungsten are usually produced by powder metallurgy methods.
To avoid oxidation, all operations are carried out in a vacuum or argon atmosphere. It is done like this. First, a mixture of metal powders is pressed, then sintered and subjected to arc melting in electric furnaces. Sometimes one tungsten powder is pressed and sintered, and the porous workpiece obtained in this way is impregnated with a liquid melt of another metal: the so-called pseudo-alloys are obtained. This method is used when it is necessary to obtain an alloy of tungsten with copper and silver.

With chromium and molybdenum, niobium and tantalum, tungsten gives ordinary (homogeneous) alloys at any ratio. Already small additions of tungsten increase the hardness of these metals and their resistance to oxidation.
Alloys with iron, nickel and cobalt are more complex. Here, depending on the ratio of components, either solid solutions or intermetallic compounds (chemical compounds of metals) are formed, and in the presence of carbon (which is always present in steel), mixed tungsten and iron carbides give the metal even greater hardness.
Very complex compounds are formed when tungsten is fused with aluminum, beryllium and titanium: in them, there are from 2 to 12 light metal atoms per tungsten atom. These alloys are heat resistant and resistant to oxidation at high temperatures.
In practice, tungsten alloys are most often used not with any one metal, but with several. Such, in particular, are acid-resistant alloys of tungsten with chromium and cobalt or nickel (amala); they make surgical instruments. The best grades of magnetic steel contain tungsten, iron and cobalt. And in special heat-resistant alloys, in addition to tungsten, there are chromium, nickel and aluminum.
Of all tungsten alloys, tungsten-containing steels have gained the most importance. They are resistant to abrasion, do not crack, retain hardness up to a red heat temperature. A tool made of them not only makes it possible to sharply intensify metalworking processes (the processing speed of metal products increases by 10-15 times), but also lasts much longer than the same tool made of other steel.
Tungsten alloys are not only heat-resistant, but also heat-resistant. They do not corrode at high temperatures under the influence of air, moisture and various chemicals. In particular, 10% tungsten introduced into nickel is enough to increase the corrosion resistance of the latter by 12 times! And tungsten carbides with the addition of tantalum and titanium carbides, cemented with cobalt, are resistant to the action of many acids - nitric, sulfuric and hydrochloric - even when boiled. Only a mixture of hydrofluoric and nitric acids is dangerous to them.

Tungsten plays an extremely important role in modern technology. It is used in the steel industry, in the production of hard alloys, in the production of acid-resistant and other special alloys, in electrical engineering, in the production of dyes, as chemical reagents, etc.

About 70% of all mined tungsten goes to the production of ferrotungsten, in the form of which it is introduced into steel. In the richest in tungsten and the most common tungsten steels (in high-speed cutting steels), tungsten forms complex tungsten-containing carbides that increase the hardness of the steel, especially at elevated temperatures (red hardness). many times increase the cutting speed. At present, high-speed steel cutters are giving way to cutters made of cermet hard alloys made on the basis of tungsten carbide with the addition of a cementing additive. Titanium, tantalum, and niobium carbides are also introduced into some hard alloys. Modern cutting speeds achieved by production innovators are obtained precisely with hard alloy cutters. Tungsten alloys with other metals have a wide variety of applications: nickel-tungsten-chromium alloy is distinguished by acid-resistant properties. Attention is drawn to tungsten alloys with increased heat resistance: for example, the addition of 1% niobium, tantalum, molybdenum, which form a solid solution with tungsten, increases the melting point of the metal above 3300 ° C., while the addition of 1% iron, which is very slightly soluble in tungsten , lowers the melting point to 1640°C. Research in this area is widely developed in the USA.

Metal tungsten finds various applications in electrical and X-ray engineering. The filaments of electric lamps are made from tungsten. Tungsten is especially suitable for this purpose due to its high refractoriness and very low volatility: at temperatures of the order of 2500 ° C, at which the filaments operate, the vapor pressure of tungsten does not reach 1 mm Hg. Metallic tungsten is also used to make heaters for electric furnaces that can withstand temperatures up to 3000°C. Metallic tungsten is used for anticathodes of X-ray tubes, for various parts of electrovacuum equipment, for radio devices, current rectifiers, etc. Thin tungsten filaments are used in galvanometers. Similar threads are used for surgical purposes. Finally, tungsten metal is used to make various coil springs, as well as parts that require a material that is resistant to various chemical influences.

Tungsten compounds have been used very widely as dyes. In China, ancient porcelain products, painted in an unusual peach color, have been preserved, studies have shown that the paint contains tungsten.

Salts of tungsten are used to impart fire resistance to some fabrics. Heavy expensive silks owe their beauty to the tungsten salts with which they are impregnated.

Pure tungsten preparations are used in chemical analysis as reagents for alkaloids and other substances. Tungsten compounds are also used as catalysts.

1. We offer the following tungsten products: tungsten strip, tungsten wire, tungsten rod, tungsten rod.

The use of pure metal and tungsten-containing alloys is based mainly on their refractoriness, hardness and chemical resistance. Pure tungsten is used in the manufacture of filaments for electric incandescent lamps and cathode ray tubes, in the production of crucibles for the evaporation of metals, in the contacts of automobile ignition distributors, in X-ray tube targets; as windings and heating elements in electric furnaces and as a structural material for space and other vehicles operating at high temperatures. High speed steels (17.5-18.5% tungsten), stellite (based on cobalt with the addition of Cr, W, C), hastalloy (stainless steel based on Ni) and many other alloys contain tungsten. The basis for the production of tool and heat-resistant alloys is ferrotungsten (68-86% W, up to 7% Mo and iron), which is easily obtained by direct reduction of wolframite or scheelite concentrates. "Pobedit" - a very hard alloy containing 80-87% tungsten, 6-15% cobalt, 5-7% carbon, is indispensable in metal processing, in the mining and oil industries.

Calcium and magnesium tungstates are widely used in fluorescent devices, other tungsten salts are used in the chemical and tanning industries. Tungsten disulfide is a dry high-temperature lubricant, stable up to 500°C. Tungsten bronzes and other element compounds are used in the manufacture of paints. Many tungsten compounds are excellent catalysts.

For many years since its discovery, tungsten remained a laboratory rarity, only in 1847 Oxland received a patent for the production of sodium tungstate, tungstic acid and tungsten from cassiterite (tin stone). The second patent, obtained by Oxland in 1857, described the production of iron-tungsten alloys, which form the basis of modern high-speed steels.

In the middle of the 19th century the first attempts were made to use tungsten in steel production, but for a long time it was not possible to introduce these developments into industry due to the high price of the metal. The increased demand for alloyed and high-strength steels led to the launch of high speed steels at Bethlehem Steel. Samples of these alloys were first presented in 1900 at the World Exhibition in Paris.

Manufacturing technology of tungsten filaments and its history.

The volumes of production of tungsten wire have a small share among all branches of application of tungsten, but the development of technology for its production has played a key role in the development of powder metallurgy of refractory compounds.

Since 1878, when Swan demonstrated in Newcastle the eight- and sixteen-candle charcoal lamps he had invented, there has been a search for a more suitable material for making filaments. The first charcoal lamp had an efficiency of only 1 lumen/watt, which was increased over the next 20 years by modifications to the methods of charcoal processing by a factor of two and a half. By 1898, the light output of such light bulbs was 3 lumens/watt. In those days, carbon filaments were heated by passing an electric current in an atmosphere of heavy hydrocarbon vapors. During the pyrolysis of the latter, the resulting carbon filled the pores and irregularities of the thread, giving it a bright metallic sheen.

At the end of the 19th century von Welsbach made the first metal filament for incandescent lamps. He made it from osmium (T pl = 2700 ° C). Osmium filaments had an efficiency of 6 lumens / watt, however, osmium is a rare and extremely expensive element of the platinum group, therefore it has not found wide application in the manufacture of household devices. Tantalum, with a melting point of 2996°C, was widely used in the form of drawn wire from 1903 to 1911 thanks to the work of von Bolton of Siemens and Halske. The efficiency of tantalum lamps was 7 lumens/watt.

Tungsten began to be used in incandescent lamps in 1904 and replaced all other metals in this capacity by 1911. A conventional incandescent lamp with a tungsten filament has a glow of 12 lumens / watt, and lamps operating under high voltage - 22 lumens / watt. Modern fluorescent lamps with a tungsten cathode have an efficiency of about 50 lumens/watt.

In 1904, Siemens-Halske tried to apply the wire drawing process developed for tantalum to more refractory metals such as tungsten and thorium. The rigidity and lack of malleability of tungsten prevented the process from running smoothly. However, later, in 1913-1914, it was shown that molten tungsten could be rolled and drawn using a partial reduction procedure. An electric arc was passed between a tungsten rod and a partially molten tungsten droplet placed in a graphite crucible coated on the inside with tungsten powder and located in a hydrogen atmosphere. Thus, small drops of molten tungsten were obtained, about 10 mm in diameter and 20-30 mm in length. Although with difficulty, it was already possible to work with them.

In the same years, Just and Hannaman patented a process for making tungsten filaments. Fine metal powder was mixed with an organic binder, the resulting paste was passed through spinnerets and heated in a special atmosphere to remove the binder, and a fine filament of pure tungsten was obtained.

The well-known extrusion process was developed in 1906-1907 and was used until the early 1910s. Very finely ground black tungsten powder was mixed with dextrin or starch until a plastic mass was formed. Hydraulic pressure forced this mass through thin diamond sieves. The thread thus obtained was strong enough to be wound on spools and dried. Next, the threads were cut into “hairpins”, which were heated in an inert gas atmosphere to a red-hot temperature to remove residual moisture and light hydrocarbons. Each "hairpin" was fixed in a clamp and heated in a hydrogen atmosphere to a bright glow by passing an electric current. This led to the final removal of unwanted impurities. At high temperatures, individual small particles of tungsten fuse and form a uniform solid metal filament. These threads are elastic, although fragile.

At the beginning of the 20th century Yust and Hannaman developed a different process that is notable for its originality. A carbon filament 0.02 mm in diameter was coated with tungsten by heating it in an atmosphere of hydrogen and tungsten hexachloride vapor. The thread coated in this way was heated to a bright glow in hydrogen under reduced pressure. In this case, the tungsten shell and the carbon core were completely fused with each other, forming tungsten carbide. The resulting thread was white and brittle. Next, the filament was heated in a stream of hydrogen, which interacted with carbon, leaving a compact filament of pure tungsten. The threads had the same characteristics as obtained in the extrusion process.

In 1909 an American Coolidge it was possible to obtain malleable tungsten without the use of fillers, but only with the help of reasonable temperature and mechanical processing. The main problem in obtaining tungsten wire was the rapid oxidation of tungsten at high temperatures and the presence of a grain structure in the resulting tungsten, which led to its brittleness.

Modern production of tungsten wire is a complex and precise technological process. The raw material is powdered tungsten obtained by the reduction of ammonium paratungstate.

The tungsten powder used for wire production must be of high purity. Usually, tungsten powders of various origins are mixed in order to average the quality of the metal. They are mixed in mills and, in order to avoid oxidation of the metal heated by friction, a stream of nitrogen is passed into the chamber. Then the powder is pressed in steel molds on hydraulic or pneumatic presses (5-25 kg/mm2). If contaminated powders are used, the compact is brittle and a fully oxidizable organic binder is added to eliminate this effect. At the next stage, preliminary sintering of the rods is performed. When the compacts are heated and cooled in a hydrogen flow, their mechanical properties improve. The compacts are still quite brittle, and their density is 60-70% of the density of tungsten, so the rods are subjected to high-temperature sintering. The rod is clamped between water-cooled contacts, and in an atmosphere of dry hydrogen a current is passed through it to heat it almost to its melting point. Due to heating, tungsten is sintered and its density increases to 85-95% of the crystalline one, at the same time, grain sizes increase, tungsten crystals grow. This is followed by forging at a high (1200-1500 ° C) temperature. In a special apparatus, the rods are passed through a chamber, which is compressed by a hammer. For one pass, the diameter of the rod is reduced by 12%. When forged, tungsten crystals elongate, creating a fibrillar structure. After forging, wire drawing follows. The rods are lubricated and passed through a sieve of diamond or tungsten carbide. The degree of extraction depends on the purpose of the resulting products. The resulting wire diameter is about 13 µm.