Titan period. Physical characteristics and properties of one of the hardest metals - titanium

Titanium in the form of oxide (IV) was discovered by the English amateur mineralogist W. Gregor in 1791 in the magnetic ferruginous sands of the town of Menacan (England); in 1795, the German chemist M. G. Klaproth established that the mineral rutile is a natural oxide of the same metal, which he called “titanium” [in Greek mythology, the titans are the children of Uranus (Heaven) and Gaia (Earth)]. It was not possible for a long time to isolate Titanium in its pure form; only in 1910, the American scientist M.A. Hunter obtained the metal Titan by heating its chloride with sodium in a sealed steel bomb; The metal he obtained was ductile only at elevated temperatures and brittle at room temperature due to the high content of impurities. The opportunity to study the properties of pure Titanium appeared only in 1925, when the Dutch scientists A. Van Arkel and I. de Boer obtained a high-purity metal, plastic at low temperatures, using the thermal dissociation of titanium iodide.

Distribution of Titan in nature. Titanium is one of the common elements, its average content in the earth's crust (clarke) is 0.57% by weight (among structural metals it ranks 4th in abundance, behind iron, aluminum and magnesium). Most of Titanium is in the basic rocks of the so-called “basalt shell” (0.9%), less in the rocks of the “granite shell” (0.23%), and even less in ultrabasic rocks (0.03%), etc. To rocks , enriched in Titanium, include pegmatites of basic rocks, alkaline rocks, syenites and associated pegmatites and others. There are 67 known Titanium minerals, mostly of igneous origin; the most important are rutile and ilmenite.

In the biosphere, Titan is mostly scattered. Sea water contains 10 -7% of it; Titan is a weak migrant.

Physical properties of Titan. Titanium exists in the form of two allotropic modifications: below a temperature of 882.5 °C, the α-form with a hexagonal close-packed lattice (a = 2.951 Å, c = 4.679 Å) is stable, and above this temperature the β-form with a body-centered cubic lattice is stable, a = 3.269 Å. Impurities and alloying additives can significantly change the α/β transformation temperature.

The density of the α-form at 20°C is 4.505 g/cm 3 , and at 870°C 4.35 g/cm 3 ; β-form at 900°C 4.32 g/cm 3 ; atomic radius Ti 1.46 Å, ionic radii Ti + 0.94 Å, Ti 2+ 0.78 Å, Ti 3+ 0.69 Å, Ti 4+ 0.64 Å; Melting point 1668 °C, boiling point 3227 °C; thermal conductivity in the range 20-25°C 22.065 W/(m K); temperature coefficient of linear expansion at 20°C 8.5·10 -6, in the range 20-700°C 9.7·10 -6; heat capacity 0.523 kJ/(kg K); electrical resistivity 42.1·10 -6 ohm·cm at 20 °C; temperature coefficient of electrical resistance 0.0035 at 20 °C; has superconductivity below 0.38 K. Titanium is paramagnetic, specific magnetic susceptibility 3.2·10 -6 at 20 °C. Tensile strength 256 MN/m2 (25.6 kgf/mm2), relative elongation 72%, Brinell hardness less than 1000 MN/m2 (100 kgf/mm2). Normal elastic modulus 108,000 MN/m2 (10,800 kgf/mm2). Metal of high purity is malleable at ordinary temperatures.

Technical Titanium used in industry contains impurities of oxygen, nitrogen, iron, silicon and carbon, which increase its strength, reduce ductility and affect the temperature of the polymorphic transformation, which occurs in the range of 865-920 °C. For technical Titanium grades VT1-00 and VT1-0, the density is about 4.32 g/cm 3 , tensile strength 300-550 MN/m 2 (30-55 kgf/mm 2), elongation not lower than 25%, Brinell hardness 1150 -1650 Mn/m 2 (115-165 kgf/mm 2). The configuration of the outer electron shell of the Ti atom is 3d 2 4s 2.

Chemical properties of Titan. Pure Titanium is a chemically active transition element; in compounds it has an oxidation state of +4, less often +3 and +2. At ordinary temperatures and up to 500-550 °C it is corrosion resistant, which is explained by the presence of a thin but durable oxide film on its surface.

It reacts noticeably with atmospheric oxygen at temperatures above 600 °C to form TiO 2 . If there is insufficient lubrication, thin titanium shavings can catch fire during machining. If there is a sufficient oxygen concentration in the environment and the oxide film is damaged by impact or friction, the metal may ignite at room temperature and in relatively large pieces.

The oxide film does not protect titanium in liquid state from further interaction with oxygen (unlike, for example, aluminum), and therefore its melting and welding must be carried out in a vacuum, in a neutral gas atmosphere or submerged arc. Titanium has the ability to absorb atmospheric gases and hydrogen, forming brittle alloys unsuitable for practical use; in the presence of an activated surface, hydrogen absorption occurs already at room temperature at a low rate, which increases significantly at 400 °C and above. The solubility of hydrogen in Titan is reversible, and this gas can be removed almost completely by annealing in a vacuum. Titanium reacts with nitrogen at temperatures above 700 °C, and nitrides of the TiN type are obtained; in the form of a fine powder or wire, titanium can burn in a nitrogen atmosphere. The diffusion rate of nitrogen and oxygen in Titan is much lower than that of hydrogen. The layer resulting from interaction with these gases is characterized by increased hardness and brittleness and must be removed from the surface of titanium products by etching or mechanical treatment. Titanium interacts vigorously with dry halogens and is stable against wet halogens, since moisture plays the role of an inhibitor.

The metal is resistant to nitric acid all concentrations (with the exception of red fuming, which causes corrosion cracking of Titan, and the reaction sometimes occurs with an explosion), in weak solutions of sulfuric acid (up to 5% by weight). Hydrochloric, hydrofluoric, concentrated sulfuric, as well as hot organic acids: oxalic, formic and trichloroacetic react with Titan.

Titanium is corrosion resistant in atmospheric air, sea water and sea atmosphere, in wet chlorine, chlorine water, hot and cold chloride solutions, in various technological solutions and reagents used in chemical, oil, paper-making and other industries, as well as in hydrometallurgy. Titanium forms metal-like compounds with C, B, Se, Si, characterized by refractoriness and high hardness. TiC carbide (mp 3140 °C) is obtained by heating a mixture of TiO 2 with soot at 1900-2000 °C in a hydrogen atmosphere; TiN nitride (mp 2950 °C) - by heating Titanium powder in nitrogen at temperatures above 700 °C. Silicides TiSi 2, TiSi and borides TiB, Ti 2 B 5, TiB 2 are known. At temperatures of 400-600 °C Titanium absorbs hydrogen to form solid solutions and hydrides (TiH, TiH 2). When TiO 2 is fused with alkalis, titanic acid salts are formed: meta- and ortho-titanates (for example, Na 2 TiO 3 and Na 4 TiO 4), as well as polytitanates (for example, Na 2 Ti 2 O 5 and Na 2 Ti 3 O 7). Titanates include the most important minerals of Titan, for example, ilmenite FeTiO 3, perovskite CaTiO 3. All titanates are slightly soluble in water. Titanium (IV) oxide, titanic acids (precipitates), and titanates dissolve in sulfuric acid to form solutions containing titanyl sulfate TiOSO 4 . When diluting and heating solutions, H 2 TiO 3 is deposited as a result of hydrolysis, from which Titanium (IV) oxide is obtained. When hydrogen peroxide is added to acidic solutions containing Ti (IV) compounds, peroxide (supratitanic) acids of the composition H 4 TiO 5 and H 4 TiO 8 and their corresponding salts are formed; these compounds are colored yellow or orange-red (depending on the concentration of Titanium), which is used for analytical definition Titan.

Getting Titan. The most common method for obtaining metal Titanium is the magnesium-thermal method, that is, the reduction of Titanium tetrachloride with metallic magnesium (less commonly, sodium):

TiCl 4 + 2Mg = Ti + 2MgCl 2.

In both cases, the starting raw materials are Titanium oxide ores - rutile, ilmenite and others. In the case of ilmenite type ores, Titanium in the form of slag is separated from the iron by smelting in electric furnaces. The slag (as well as rutile) is chlorinated in the presence of carbon to form Titanium tetrachloride, which, after purification, enters a reduction reactor with a neutral atmosphere.

Titanium in this process is obtained in sponge form and, after grinding, is melted in vacuum arc furnaces into ingots with the introduction of alloying additives, if an alloy is required. Magnesium-thermal method allows you to create large industrial production Titanium with a closed technological cycle, since the by-product formed during reduction - magnesium chloride - is sent for electrolysis to produce magnesium and chlorine.

In some cases, it is advantageous to use powder metallurgy methods for the production of products from Titanium and its alloys. To obtain particularly fine powders (for example, for radio electronics), reduction of Titanium (IV) oxide with calcium hydride can be used.

Application of Titan. The main advantages of Titan over other structural metals: a combination of lightness, strength and corrosion resistance. Titanium alloys in absolute, and even more so in specific strength (i.e., strength related to density) are superior to most alloys based on other metals (for example, iron or nickel) at temperatures from -250 to 550 ° C, and in terms of corrosion they comparable to alloys of noble metals. However, Titanium began to be used as an independent structural material only in the 50s of the 20th century due to the great technical difficulties of its extraction from ores and processing (which is why Titanium was conventionally classified as a rare metal). The main part of Titan is spent on the needs of aviation and rocket technology and marine shipbuilding. Alloys of Titanium with iron, known as ferrotitanium (20-50% Titanium), in metallurgy quality steels and special alloys serve as an alloying additive and deoxidizing agent.

Technical Titanium is used for the manufacture of containers, chemical reactors, pipelines, fittings, pumps and other products operating in aggressive environments, for example, in chemical engineering. In the hydrometallurgy of non-ferrous metals, equipment made of Titanium is used. It is used to coat steel products. The use of Titanium in many cases provides a great technical and economic effect not only due to increased service life of equipment, but also the possibility of intensifying processes (as, for example, in nickel hydrometallurgy). The biological safety of Titanium makes it an excellent material for the manufacture of equipment for Food Industry and in reconstructive surgery. In deep cold conditions, the strength of Titan increases while maintaining good ductility, which makes it possible to use it as a structural material for cryogenic technology. Titanium lends itself well to polishing, color anodizing and other surface finishing methods and therefore is used for the manufacture of various artistic products, including monumental sculpture. An example is the monument in Moscow, built in honor of the launch of the first artificial Earth satellite. From Titanium compounds practical significance have oxides, halides, and silicides used in technology high temperatures; borides and their alloys used as moderators in nuclear power plants due to their refractoriness and large neutron capture cross section. Titanium carbide, which has high hardness, is part of tool hard alloys used for the manufacture of cutting tools and as an abrasive material.

Titanium (IV) oxide and barium titanate form the basis of titanium ceramics, and barium titanate is the most important ferroelectric.

Titanium in the body. Titanium is constantly present in the tissues of plants and animals. In terrestrial plants its concentration is about 10 -4%, in marine plants - from 1.2 10 -3 to 8 10 -2%, in the tissues of terrestrial animals - less than 2 10 -4%, in marine ones - from 2 10 -4 to 2·10 -2%. Accumulates in vertebrates mainly in horn formations, spleen, adrenal glands, thyroid gland, placenta; poorly absorbed from the gastrointestinal tract. In humans, the daily intake of Titanium from food and water is 0.85 mg; excreted in urine and feces (0.33 and 0.52 mg, respectively).

Titanium and its alloys are widely used in the most different areas. First of all, titanium alloys have been found wide application in the construction of various equipment due to its high corrosion resistance, mechanical strength, low density, heat resistance and many other characteristics. Considering the properties and applications of titanium, one cannot help but note its rather high cost. However, it is fully compensated by the characteristics and durability of the material.

Titanium has high strength and melting point, and differs from other metals in durability.

Basic properties of titanium

Titanium is in group IV of the fourth period of the periodic table of chemical elements. In the most stable and most important compounds the element is tetravalent. Externally, titanium resembles steel. It is a transitional element. The melting point reaches almost 1700°, and the boiling point - 3300°. As for such properties as the latent heat of melting and evaporation, for titanium it is almost 2 times higher than for iron.

It has 2 allotropic modifications:

1. Low temperature, which can exist up to a temperature of 882.5°.
2. High temperature, stable from a temperature of 882.5° to the melting point.

Properties such as specific heat capacity and density place titanium between the two materials with the most widespread structural use: iron and aluminum. Mechanical strength titanium is almost 2 times higher than this characteristic of pure iron and almost 6 times that of aluminum. However, the properties of titanium are such that it is capable of absorbing large quantities hydrogen, oxygen and nitrogen, which negatively affects the plastic characteristics of the material.

The material is characterized by very low thermal conductivity. For comparison, for iron it is 4 times higher, and for aluminum it is 12 times higher. As for such a property as the coefficient of thermal expansion, at room temperature it has a relatively low value and increases with increasing temperature.

Titanium has low elastic moduli. When the temperature rises to 350°, they begin to decrease almost linearly. It is this point that is a significant drawback of the material.

Titan is characterized quite great value electrical resistivity. It can fluctuate within fairly wide limits and depends on the content of impurities.

Titanium is a paramagnetic material. Such substances are characterized by a decrease in magnetic susceptibility during heating. However, titanium is an exception - as the temperature rises, its magnetic susceptibility increases significantly.

Areas of application of titanium

Medical instruments made of titanium alloy are characterized by high corrosion resistance, biological resistance and ductility.

The properties of the material provide a fairly wide range of areas for its application. Thus, titanium alloys are used in large quantities in the construction of ships and various equipment. The material has been used as an alloying additive for high-quality steels and as a deoxidizing agent. Alloys with nickel have found application in technology and medicine. Such compounds have unique properties, in particular, they have shape memory.

The use of compact titanium in the production of parts for electric vacuum devices used at high temperatures has been established. The properties of technical titanium make it possible to use it in the production of valves, pipelines, pumps, fittings and other products created for use in aggressive conditions.

The alloys are characterized by insufficient thermal strength, but have high corrosion resistance. This allows the use of various titanium-based alloys in the chemical field. For example, the material is used in the manufacture of pumps for pumping sulfuric and of hydrochloric acid. Today, only alloys based on this material can be used in the production of various types of equipment for the chlorine industry.

Use of titanium in the transport industry

Alloys based on this material are used in the manufacture of armored vehicles. And replacing a variety of structural elements used in the transportation industry can reduce fuel consumption, increase payload capacity, increase the fatigue limit of products, and improve many other characteristics.

When producing equipment for the chemical industry from titanium, the most important property is the corrosion resistance of the metal.

The material is well suited for use in construction railway transport. One of the main problems that needs to be solved in railways, is associated with a decrease in dead weight. The use of rods and sheets made of titanium can significantly reduce the total mass of the composition, reduce the size of axle boxes and journals, and save on traction.

Weight is also quite significant for trailer vehicles. The use of titanium instead of steel in the production of wheels and axles also significantly increases payload capacity.

The properties of the material make it possible to use it in the automotive industry. The material is characterized by an optimal combination of strength and weight properties for exhaust gas removal systems and coil springs. The use of titanium and its alloys can significantly reduce the volume of exhaust gases, reduce fuel costs and expand the use of scrap and industrial waste by remelting them. The material and alloys containing it have many advantages compared to other solutions used.

The main task of developing new parts and structures is to reduce their mass, on which the movement of the vehicle itself depends to one degree or another. vehicle. Reducing the weight of moving components and parts makes it possible to potentially reduce fuel costs. Titanium parts have repeatedly proven their reliability. They are widely used in the aerospace industry and racing car designs.

The use of this material allows not only to reduce the weight of parts, but also to solve the issue of reducing the volume of exhaust gases.

Use of titanium and its alloys in construction

An alloy of titanium and zinc is widely used in construction. This alloy is characterized by high mechanical properties and corrosion resistance, and is characterized by high rigidity and ductility. The alloy contains up to 0.2% alloying additives that act as structure modifiers. Thanks to aluminum and copper, the required ductility is ensured. In addition, the use of copper increases the tensile strength of the material, and the combination of chemical elements helps to reduce the expansion coefficient. The alloy is also used for the production of long strips and sheets with good aesthetic characteristics.

Titanium is often used in space technology due to its lightness, strength and refractoriness.

Among the main qualities of the titanium-zinc alloy, which are important specifically for construction, the following chemical and physical properties as high corrosion resistance, good appearance and safety for human health and the environment.

The material has good plasticity and can be deep-drawn without problems, which allows it to be used in roofing work. The alloy has no problems with soldering. That is why various volumetric structures and non-standard architectural elements such as domes and spiers are made of zinc-titanium, rather than copper or galvanized steel. In solving such problems, this alloy is indispensable.

The scope of use of the alloy is very wide. It is used in facade and roofing work, products of various configurations and almost any complexity are made from it, it is widely used in the production of various decorative products such as gutters, flashings, roof ridges, etc.

This alloy has a very long service life. For more than a century it will not require painting or frequent maintenance work. Also among the significant advantages of the material, one should highlight its ability to recover. Minor damage in the form of scratches from branches, birds, etc. After some time they disappear on their own.

The requirements for building materials are becoming more serious and stringent. Research companies in a number of countries have studied the soil around buildings built using an alloy of zinc and titanium. The research results confirmed that the material is completely safe. It has no carcinogenic properties and does not harm human health. Zinc-titanium is a non-flammable building material, which further increases safety.

Taking into account all the above positive characteristics such construction material in operation approximately 2 times cheaper than roofing copper.

The alloy has two oxidation states. Over time, it changes color and loses its metallic luster. At first, zinc-titanium becomes light gray, and after some time it acquires a noble dark gray hue. Currently, the material is deliberately chemically aged.

Use of titanium and its alloys in medicine

Titanium is highly compatible with human tissue, therefore it is actively used in the field of endoprosthetics.

Titanium has also found wide application in the medical field. Among the advantages that allowed it to become so popular are its high strength and corrosion resistance. In addition, none of the patients were allergic to titanium.

Commercially pure titanium and Ti6-4Eli alloy are used in medicine. It is used to make surgical instruments, a variety of external and internal prostheses, including heart valves. Wheelchairs, crutches and other devices are made from titanium.

A number of studies and experiments confirm the excellent biological compatibility of the material and its alloys with living human tissue. Soft and bone tissues grow together with these materials without problems. And the low modulus of elasticity and high specific strength make titanium very good material for endoprosthetics. It is noticeably lighter than tin, steel and cobalt-based alloys.

Thus, the properties of titanium make it possible to actively use it in a wide variety of fields - from the manufacture of pipes and roofing to medical prosthetics and the construction of spacecraft.

Titanium- an element of the secondary subgroup of the fourth group, the fourth period of the periodic table of chemical elements, with atomic number 22. Denoted by the symbol Ti (lat. Titanium). Simple substance titanium (CAS number: 7440-32-6) - light metal silver-white color. Exists in two crystal modifications: ?-Ti with a hexagonal close-packed lattice, -Ti with cubic body-centered packing, transition temperature α↔β 883 °C

History of the discovery of the element Titan

The discovery of TiO2 was made almost simultaneously and independently of each other by the Englishman W. Gregor and the German chemist M. G. Klaproth. W. Gregor, studying the composition of magnetic ferruginous sand (Creed, Cornwall, England, 1789), isolated a new “earth” (oxide) of an unknown metal, which he called menaken. In 1795, the German chemist Klaproth discovered a new element in the mineral rutile and named it titanium. Two years later, Klaproth established that rutile and menaken earth are oxides of the same element, which gave rise to the name “titanium” proposed by Klaproth. Ten years later, titanium was discovered for the third time. The French scientist L. Vauquelin discovered titanium in anatase and proved that rutile and anatase are identical titanium oxides.

The first sample of titanium metal was obtained in 1825 by J. Ya. Berzelius. Due to the high chemical activity of titanium and the difficulty of its purification, a pure sample of Ti was obtained by the Dutch A. van Arkel and I. de Boer in 1925 by thermal decomposition of titanium iodide vapor TiI4.

origin of name

The metal got its name in honor of the Titans, characters from ancient Greek mythology, the children of Gaia. The name of the element was given by Martin Klaproth, in accordance with his views on chemical nomenclature, in contrast to the French school of chemistry, where they tried to name the element by its chemical properties. Since the German researcher himself noted the impossibility of determining the properties of a new element only from its oxide, he chose a name for it from mythology, by analogy with uranium he had previously discovered.

However, according to another version, published in the journal “Technology-Youth” in the late 80s, the newly discovered metal owes its name not to the mighty titans from ancient Greek myths, but to Titania, the fairy queen in Germanic mythology (the wife of Oberon in Shakespeare’s “A Midsummer Night’s Dream” ). This name is associated with the extraordinary “lightness” (low density) of the metal.

Being in nature

Titanium is in 10th place in terms of prevalence in nature. Content in the earth's crust is 0.57% by weight. Not found in free form. More than 100 minerals containing titanium are known. The most important of them are: rutile TiO 2 , ilmenite FeTiO 3 , titanomagnetite FeTiO 3 + Fe 3 O 4 , perovskite CaTiO 3 , titanite CaTiOSiO 4 , tantalite (Fe,Mn) 2+ Ta 2 O 6 and manganotantalitite MnT 2 O 6 . There are primary titanium ores - ilmenite-titanomagnetite and placer ores - rutile-ilmenite-zircon.

Reserves and production

As of 2002, 90% of mined titanium was used to produce titanium dioxide TiO 2 . World production titanium dioxide amounted to 4.5 million tons per year. Confirmed reserves of titanium dioxide (excluding Russia) are about 800 million tons. As of 2006, according to the US Geological Survey, in terms of titanium dioxide and excluding Russia, reserves of ilmenite ores amount to 603–673 million tons, and rutile ores - 49.7–52.7 million tons. At the current rate of extraction of the world's proven reserves of titanium (without accounting of Russia) x lasts more than 150 years.

Russia has the second largest reserves of titanium in the world, after China. The mineral resource base of titanium in Russia consists of 20 deposits (of which 11 are primary and 9 alluvial), fairly evenly distributed throughout the country. The largest of the explored deposits is located 25 km from the city of Ukhta (Komi Republic). The deposit's reserves are estimated at 2 billion tons.

The world's largest titanium producer - Russian company"VSMPO-AVISMA".

Receipt

A block of crystalline titanium (purity 99.995%, weight? 283 g, length? 14 cm, diameter? 25 mm), manufactured at the Uralredmet plant using the van Arkel and de Boer iodide method

Titanium ore concentrate is subjected to sulfuric acid or pyrometallurgical processing. The product of sulfuric acid treatment is titanium dioxide powder TiO 2 . Using the pyrometallurgical method, the ore is sintered with coke and treated with chlorine, producing titanium tetrachloride vapor TiCl 4: TiO 2 + 2C + 2Cl 2 = TiCl 4 + 2CO

The resulting TiCl 4 vapors at 850 °C reduce Mg: TiCl 4 + 2Mg = 2MgCl 2 + Ti

The resulting titanium “sponge” is melted down and cleaned. Ilmenite concentrates are reduced in electric arc furnaces, followed by chlorination of the resulting titanium slag. Titanium is refined using the iodide method or electrolysis, separating Ti from TiCl 4 . To obtain titanium ingots, arc, electron beam or plasma processing is used.

Physical properties

Titanium is a lightweight silvery-white metal. Exists in two crystal modifications: ?-Ti with a hexagonal close-packed lattice (a=2.951 A; c=4.697 A; z=2; space group C6mmc), ?-Ti with cubic body-centered packing (a=3.269 A; z=2; space group Im3m), transition temperature?-? 883 °C, ?H transition 3.8 kJ/mol. Melting point 1671 °C, boiling point 3260 °C, density ?-Ti and ?-Ti respectively equal to 4.505 (20 °C) and 4.32 (900 °C) g/cm?, atomic density 5.71 × 1022 at /cm³. Plastic, weldable in an inert atmosphere.

Has high viscosity, with machining prone to sticking to the cutting tool, and therefore requires the application of special coatings to the tool and various lubricants.

At ordinary temperatures it is covered with a protective passivating film of TiO 2 oxide, making it corrosion resistant in most environments (except alkaline).

Titanium dust tends to explode. Flash point 400°C.

Chemical properties

Titanium is resistant to dilute solutions of many acids and alkalis (except H 3 PO 4 and concentrated

Story

The discovery of titanium dioxide (TiO 2) was made almost simultaneously and independently by an Englishman W. Gregor and German chemist M. G. Klaproth. W. Gregor, studying the composition of magnetic ferruginous sand (Creed, Cornwall, England), isolated a new “earth” (oxide) of an unknown metal, which he called menaken. In 1795, the German chemist Klaproth discovered in the mineral rutile a new element and named it titanium. Two years later, Klaproth established that rutile and menaken earth are oxides of the same element, which gave rise to the name “titanium” proposed by Klaproth. After 10 years, the discovery of titanium took place for the third time: a French scientist L. Vauquelin discovered titanium in anatase and proved that rutile and anatase are identical titanium oxides.

The first sample of titanium metal was received in 1825 Swede J. J. Berzelius. Due to the high chemical activity of titanium and the difficulty of its purification, a pure sample of Ti was obtained by the Dutchmen A. van Arkel and I. de Boer in 1925 thermal vapor decomposition titanium iodide TiI 4.

Titan was not found industrial applications, Bye Luxembourger G. Kroll (English) Russian in 1940 did not patent a simple magnesium-thermal method for the recovery of titanium metal from tetrachloride; this method (Kroll process (English) Russian) to this day remains one of the main ones in the industrial production of titanium.

origin of name

The metal got its name in honor titans, characters from ancient Greek mythology, children Gays. Gave the name to the element Martin Klaproth in accordance with his views on chemical nomenclature, as opposed to the French school of chemistry, where they tried to name an element by its chemical properties. Since the German researcher himself noted the impossibility of determining the properties of a new element only by its oxide, he chose a name for it from mythology, by analogy with what he had previously discovered uranium.

Being in nature

Titanium is in 10th place in terms of prevalence in nature. Contents in earth's crust- 0.57% by weight, in sea ​​water- 0.001 mg/l. IN ultramafic rocks 300 g/t, in the main - 9 kg/t, in sour 2.3 kg/t, in clays And shale 4.5 kg/t. In the earth's crust, titanium is almost always tetravalent and is present only in oxygen compounds. Not found in free form. Titanium under conditions of weathering and deposition has a geochemical affinity with Al2O3. It concentrates in bauxite weathering crust and in marine clayey sediments. Titanium is transferred in the form of mechanical fragments of minerals and in the form colloids. Up to 30% TiO 2 by weight accumulates in some clays. Titanium minerals are resistant to weathering and form large concentrations in placers. More than 100 minerals containing titanium are known. The most important of them: rutile TiO2, ilmenite FeTiO3, titanomagnetite FeTiO 3 + Fe 3 O 4, perovskite CaTiO3, titanite(sphene) CaTiSiO 5 . There are indigenous ore titanium - ilmenite-titanomagnetite and alluvial - rutile-ilmenite-zircon.

Place of Birth

Large primary titanium deposits are located in South Africa, Russia, Ukraine, Canada, USA, China, Norway, Sweden, Egypt, Australia, India, South Korea, Kazakhstan; placer deposits are found in Brazil, India, USA, Sierra Leone, and Australia. In CIS countries leading place In terms of explored reserves of titanium ores, the Russian Federation (58.5%) and Ukraine (40.2%) rank. Largest deposit in Russia - Yaregskoe.

Reserves and production

As of 2002, 90% of mined titanium was used for production titanium dioxide TiO2. World production of titanium dioxide was 4.5 million tons per year. Confirmed reserves of titanium dioxide (excluding Russia) are about 800 million tons. As of 2006, according to the US Geological Survey, in terms of titanium dioxide and excluding Russia, reserves of ilmenite ores amount to 603-673 million tons, and rutile ores - 49. 7-52.7 million tons. Thus, at the current rate of extraction, the world's proven reserves of titanium (excluding Russia) will last for more than 150 years.

Russia has the second largest reserves of titanium in the world, after China. The mineral resource base of titanium in Russia consists of 20 deposits (of which 11 are primary and 9 alluvial), fairly evenly distributed throughout the country. The largest of the explored deposits (Yaregskoye) is located 25 km from the city Ukhta(Komi Republic). The deposit's reserves are estimated at 2 billion tons of ore with an average titanium dioxide content of about 10%.

The world's largest titanium producer is the Russian company " VSMPO-AVISMA » .

Receipt

As a rule, the starting material for the production of titanium and its compounds is titanium dioxide with a relatively small amount of impurities. In particular, this could be rutile concentrate obtained from the enrichment of titanium ores. However, the reserves of rutile in the world are very limited, and the so-called synthetic rutile or titanium is more often used. slag, obtained during processing ilmenite concentrates. To obtain titanium slag, ilmenite concentrate is reduced in an electric arc furnace, while iron is separated into the metal phase ( cast iron), and unreduced titanium oxides and impurities form the slag phase. Rich slag is processed using the chloride or sulfuric acid method.

Titanium ore concentrate is subjected to sulfuric acid or pyrometallurgical processing. The product of sulfuric acid treatment is titanium dioxide powder TiO 2. Using the pyrometallurgical method, the ore is sintered with coke and process chlorine, getting pairs titanium tetrachloride TiCl4:

The resulting TiCl 4 vapors at 850 °C reduce magnesium :

In addition, the so-called FFC Cambridge process, named after its developers Derek Fray, Tom Farthing and George Chen from Cambridge University, where it was created. This electrochemical process allows direct, continuous reduction of titanium from oxide in a melt mixture calcium chloride And quicklime(calcium oxide). This process uses an electrolytic bath filled with a mixture of calcium chloride and lime, with a graphite sacrificial (or neutral) anode and a cathode made of a reducible oxide. When current is passed through the bath, the temperature quickly reaches ~1000-1100 °C, and the calcium oxide melt decomposes at the anode into oxygen and metal calcium :

The resulting oxygen oxidizes the anode (in the case of using graphite), and calcium migrates in the melt to the cathode, where it reduces titanium from its oxide:

The resulting calcium oxide again dissociates into oxygen and metallic calcium, and the process is repeated until the cathode is completely converted into a titanium sponge or the calcium oxide is exhausted. Calcium chloride in this process used as an electrolyte to impart electrical conductivity to the melt and mobility of active calcium and oxygen ions. When using an inert anode (for example, tin dioxide), instead of carbon dioxide molecular oxygen is released at the anode, which causes less pollution environment, however, the process in this case becomes less stable, and, in addition, under some conditions, the decomposition of chloride rather than calcium oxide becomes more energetically favorable, which leads to the release of molecular chlorine.

The resulting titanium “sponge” is melted down and cleaned. Titanium is refined using the iodide method or electrolysis, isolating Ti from TiCl 4 . To obtain titanium ingots, arc, electron beam or plasma processing is used.

Physical properties

Titanium - light silver-white metal. At normal pressure, it exists in two crystalline modifications: low-temperature α-Ti with a hexagonal close-packed lattice ( hexagonal system , space group C 6mmc, cell parameters a= 0.2953 nm, c= 0.4729 nm, Z = 2 ) and high-temperature β-Ti with cubic body-centered packing ( cubic system , space group Im 3m, cell parameters a= 0.3269 nm, Z = 2 ), transition temperature α↔β 883 °C, transition heat Δ H=3.8 kJ/mol (87.4 kJ/kg). Most metals, when dissolved in titanium, stabilize the β phase and reduce the temperature of the α↔β transition. At pressures above 9 GPa and temperatures above 900 °C, titanium transforms into the hexagonal phase (ω -Ti). The densities of α-Ti and β-Ti are respectively 4.505 g/cm³ (at 20 °C) and 4.32 g/cm³ (at 900 °C). The atomic density of α-titanium is 5.67⋅10 22 at/cm³.

The melting point of titanium at normal pressure is 1670 ± 2 °C, or 1943 ± 2 K (adopted as one of the secondary calibration points of the ITS-90 temperature scale (English) Russian) . Boiling point 3287 °C. At low enough temperatures (-80 °C), titanium becomes quite brittle. Molar heat capacity under normal conditions C p= 25.060 kJ/(mol K), which corresponds to a specific heat capacity of 0.523 kJ/(kg K). Heat of fusion 15 kJ/mol, heat of evaporation 410 kJ/mol. Characteristic Debye temperature 430 K. Thermal conductivity 21.9 W/(mK) at 20 °C. Temperature coefficient of linear expansion 9.2·10 −6 K −1 in the range from −120 to +860 °C. Molar entropy of α-titanium S 0 = 30.7 kJ/(mol K). For titanium in the gas phase enthalpy formation Δ H0
f= 473.0 kJ/mol, Gibbs energy Δ G0
f= 428.4 kJ/mol, molar entropy S 0 = 180.3 kJ/(mol K), heat capacity at constant pressure C p= 24.4 kJ/(mol K)

Plastic, weldable in an inert atmosphere. Strength characteristics depend little on temperature, but strongly depend on purity and pre-treatment. For technical titanium Vickers hardness is 790-800 MPa, normal elasticity modulus is 103 GPa, shear modulus 39.2 GPa. In high-purity titanium pre-annealed in vacuum yield stress 140-170 MPa, relative extension 55-70 %, Brinell hardness 716 MPa.

It has a high viscosity, during machining it is prone to sticking to the cutting tool, and therefore requires the application of special coatings to the tool, various lubricants.

At normal temperatures it is covered with a protective passivating film of TiO 2 oxide, thanks to this corrosion resistant in most environments (except alkaline).

Isotopes

Natural titanium consists of a mixture of five stable isotopes: 46 Ti ( isotopic abundance 7.95%), 47 Ti (7.75%), 48 Ti (73.45%), 49 Ti (5.51%), 50 Ti (5.34%).

Among artificial isotopes, the longest-lived is 44 Ti ( half life 60 years) and 45 Ti (half-life 184 minutes).

Chemical properties

It reacts easily even with weak acids in the presence of complexing agents, for example, it interacts with hydrofluoric acid due to the formation of a complex anion 2− . Titanium is most susceptible to corrosion in organic environments, since in the presence of water a dense layer forms on the surface of a titanium product. passive film from titanium oxides and hydride. The most noticeable increase in the corrosion resistance of titanium is noticeable when the water content in an aggressive environment increases from 0.5 to 8.0%, which is confirmed by electrochemical studies electrode potentials titanium in solutions of acids and alkalis in mixed aqueous-organic media.

When heated in air to 1200 °C Ti lights up with a bright white flame to form oxide phases of variable composition TiO x . TiO(OH) 2 ·xH 2 O hydroxide is precipitated from solutions of titanium salts, and careful calcination of which produces TiO 2 oxide. Hydroxide TiO(OH) 2 xH 2 O and dioxide TiO 2 amphoteric.

When titanium interacts with carbon is formed titanium carbide TiC x (x = 0.49-1.00).

• Titan in the form alloys is the most important structural material in aircraft, rocket and shipbuilding.
• The metal is used in the chemical industry ( reactors , pipelines , pumps , pipeline accessories), military industry (body armor, armor and fire partitions in aviation, submarine hulls), industrial processes(desalination plants, pulp and paper processes), automotive industry, agricultural industry, food industry, sporting goods, jewelry, mobile phones, light alloys, etc.
• Titanium is physiologically inert, due to which it is used in medicine (prostheses, osteoprostheses, dental implants), in dental and endodontic instruments, jewelry for piercing.
• Titanium casting is performed in vacuum furnaces in graphite molds. Vacuum lost wax casting is also used. Due to technological difficulties, it is used in artistic casting to a limited extent. The world's first monumental cast titanium sculpture is monument to Yuri Gagarin on area named after him in Moscow.
• Titan is alloying additive in many alloyed