Eternal, mysterious, cosmic, material of the future - all these and many other epithets are assigned to titanium in various sources. The history of the discovery of this metal was not trivial: at the same time, several scientists worked on isolating the element in its pure form. The process of studying the physical, chemical properties and determining the areas of its application has not been completed to date. Titanium is the metal of the future, its place in human life has not yet been finally determined, which gives modern researchers a huge scope for creativity and scientific research.
Characteristic
The chemical element titanium (Titanium) is indicated in the periodic table of D. I. Mendeleev by the symbol Ti. It is located in the secondary subgroup of group IV of the fourth period and has serial number 22. The simple substance titanium is a white-silver metal, light and durable. The electronic configuration of an atom has the following structure: +22)2)8)10)2, 1S22S22P6 3S23P63d24S2. Accordingly, titanium has several possible oxidation states: 2,3, 4, in the most stable compounds it is tetravalent.
Titanium - alloy or metal?
This question interests many. In 1910, the American chemist Hunter obtained the first pure titanium. The metal contained only 1% of impurities, but at the same time, its amount turned out to be negligible and did not make it possible to further study its properties. The plasticity of the obtained substance was achieved only under the influence of high temperatures; under normal conditions (room temperature), the sample was too fragile. In fact, this element did not interest scientists, since the prospects for its use seemed too uncertain. The difficulty of obtaining and research further reduced the potential for its application. Only in 1925, chemists from the Netherlands I. de Boer and A. Van Arkel received titanium metal, the properties of which attracted the attention of engineers and designers around the world. The history of the study of this element begins in 1790, exactly at this time, in parallel, independently of each other, two scientists discover titanium as a chemical element. Each of them receives a compound (oxide) of a substance, failing to isolate the metal in its pure form. The discoverer of titanium is the English mineralogist monk William Gregor. On the territory of his parish, located in the southwestern part of England, the young scientist began to study the black sand of the Menaken Valley. The result of experiments with a magnet was the release of shiny grains, which were a titanium compound. At the same time, in Germany, the chemist Martin Heinrich Klaproth isolated a new substance from the mineralrutile. In 1797, he also proved that elements opened in parallel are similar. Titanium dioxide has been a mystery to many chemists for more than a century, and even Berzelius was unable to obtain pure metal. The latest technologies of the 20th century significantly accelerated the process of studying the mentioned element and determined the initial directions for its use. At the same time, the scope of application is constantly expanding. Only the complexity of the process of obtaining such a substance as pure titanium can limit its scope. The price of alloys and metal is quite high, so today it cannot displace traditional iron and aluminum.
Origin of the name
Menakin - the first name for titanium, which was used until 1795. That is how, by territorial affiliation, W. Gregor called the new element. Martin Klaproth gives the element the name "titanium" in 1797. At this time, his French colleagues, led by a fairly reputable chemist A. L. Lavoisier, proposed to name the newly discovered substances in accordance with their basic properties. The German scientist did not agree with this approach, he quite reasonably believed that at the discovery stage it is rather difficult to determine all the characteristics inherent in a substance and reflect them in the name. However, it should be recognized that the term intuitively chosen by Klaproth fully corresponds to the metal - this has been repeatedly emphasized by modern scientists. There are two main theories for the origin of the name titanium. The metal could be designated so in honor of the elven queen Titania(character of Germanic mythology). This name symbolizes both the lightness and strength of the substance. Most scientists are inclined to use the version of the use of ancient Greek mythology, in which the powerful sons of the goddess of the earth Gaia were called titans. The name of the previously discovered element, uranium, also speaks in favor of this version.
Being in nature
Of the metals that are technically valuable to humans, titanium is the fourth most abundant in the earth's crust. Only iron, magnesium and aluminum are characterized by a large percentage in nature. The highest content of titanium is noted in the bas alt shell, slightly less in the granite layer. In sea water, the content of this substance is low - approximately 0.001 mg / l. The chemical element titanium is quite active, so it cannot be found in its pure form. Most often, it is present in compounds with oxygen, while it has a valency of four. The number of titanium-containing minerals varies from 63 to 75 (in various sources), while at the present stage of research, scientists continue to discover new forms of its compounds. For practical use, the following minerals are of greatest importance:
- Ilmenite (FeTiO3).
- Rutile (TiO2).
- Titanit (CaTiSiO5).
- Perovskite (CaTiO3).
- Titanomagnetite (FeTiO3+Fe3O4) etc.
All existing titanium-bearing ores are divided intoalluvial and basic. This element is a weak migrant, it can travel only in the form of rock fragments or the movement of silty bottom rocks. In the biosphere, the largest amount of titanium is found in algae. In representatives of the terrestrial fauna, the element accumulates in the horny tissues, hair. The human body is characterized by the presence of titanium in the spleen, adrenal glands, placenta, thyroid gland.
Physical properties
Titanium is a non-ferrous metal with a silvery-white color that looks like steel. At a temperature of 0 0C, its density is 4.517 g/cm3. The substance has a low specific gravity, which is typical for alkali metals (cadmium, sodium, lithium, cesium). In terms of density, titanium occupies an intermediate position between iron and aluminum, while its performance is higher than that of both elements. The main properties of metals that are taken into account when determining the scope of their application are the yield strength and hardness. Titanium is 12 times stronger than aluminum, 4 times stronger than iron and copper, while being much lighter. The plasticity of a pure substance and its yield strength make it possible to process at low and high temperatures, as in the case of other metals, i.e., by riveting, forging, welding, rolling. A distinctive characteristic of titanium is its low thermal and electrical conductivity, while these properties are preserved at elevated temperatures, up to 500 0С. In a magnetic field, titanium is a paramagnetic element, it does notis attracted like iron, and is not pushed out like copper. Very high anti-corrosion performance in aggressive environments and under mechanical stress is unique. More than 10 years of being in sea water did not change the appearance and composition of the titanium plate. Iron in this case would be completely destroyed by corrosion.
Thermodynamic properties of titanium
- Density (under normal conditions) is 4.54g/cm3.
- The atomic number is 22.
- Metal group - refractory, light.
- The atomic mass of titanium is 47.0.
- Boiling point (0С) – 3260.
- Molar volume cm3/mol – 10, 6.
- Titanium melting point (0С) – 1668.
- Specific heat of vaporization (kJ/mol) – 422, 6.
- Electrical resistance (at 20 0С) Ohmcm10-6 – 45.
Chemical properties
The increased corrosion resistance of the element is due to the formation of a small oxide film on the surface. It prevents (under normal conditions) chemical reactions with gases (oxygen, hydrogen) in the surrounding atmosphere of an element such as titanium metal. Its properties change under the influence of temperature. When it rises to 600 0С, an interaction reaction with oxygen occurs, resulting in the formation of titanium oxide (TiO2). In the case of absorption of atmospheric gases, brittle compounds are formed that have no practical application, which is why welding and melting of titanium are carried out under vacuum conditions. reversible reactionis the process of hydrogen dissolution in the metal, it occurs more actively with an increase in temperature (from 400 0С and higher). Titanium, especially its small particles (thin plate or wire), burns in a nitrogen atmosphere. A chemical reaction of interaction is possible only at a temperature of 700 0С, resulting in the formation of TiN nitride. Forms highly hard alloys with many metals, often as an alloying element. It reacts with halogens (chromium, bromine, iodine) only in the presence of a catalyst (high temperature) and subject to interaction with a dry substance. In this case, very hard refractory alloys are formed. With solutions of most alkalis and acids, titanium is chemically inactive, with the exception of concentrated sulfuric (with prolonged boiling), hydrofluoric, hot organic (formic, oxalic).
Deposits
Ilmenite ores are the most common in nature - their reserves are estimated at 800 million tons. The deposits of rutile deposits are much more modest, but the total volume - while maintaining the growth of production - should provide mankind for the next 120 years with such a metal as titanium. The price of the finished product will depend on demand and an increase in the level of manufacturability, but on average it varies in the range from 1200 to 1800 rubles/kg. In conditions of constant technical improvement, the cost of all production processes is significantly reduced with their timely modernization. China and Russia have the largest reserves of titanium ores, as well as mineralJapan, South Africa, Australia, Kazakhstan, India, South Korea, Ukraine, Ceylon have a raw material base. The deposits differ in the volume of production and the percentage of titanium in the ore, geological surveys are ongoing, which makes it possible to assume a decrease in the market value of the metal and its wider use. Russia is by far the largest producer of titanium.
Receive
For the production of titanium, titanium dioxide is most often used, containing a minimum amount of impurities. It is obtained by enrichment of ilmenite concentrates or rutile ores. In the electric arc furnace, the heat treatment of the ore takes place, which is accompanied by the separation of iron and the formation of slag containing titanium oxide. The sulfate or chloride method is used to process the iron-free fraction. Titanium oxide is a gray powder (see photo). Titanium metal is obtained by its phased processing.
The first phase is the process of sintering slag with coke and exposure to chlorine vapor. The resulting TiCl4 is reduced with magnesium or sodium when exposed to a temperature of 850 0C. Titanium sponge (porous fused mass), obtained as a result of a chemical reaction, is refined or melted into ingots. Depending on the further direction of use, an alloy or pure metal is formed (impurities are removed by heating to 1000 0С). For the production of a substance with an impurity content of 0.01%, the iodide method is used. It is based on the processevaporation from a titanium sponge pre-treated with halogen, its vapors.
Application areas
The melting point of titanium is quite high, which, given the lightness of the metal, is an invaluable advantage of using it as a structural material. Therefore, it finds the greatest application in shipbuilding, the aviation industry, the manufacture of rockets, and chemical industries. Titanium is quite often used as an alloying additive in various alloys, which have increased hardness and heat resistance characteristics. High anti-corrosion properties and the ability to withstand most aggressive environments make this metal indispensable for the chemical industry. Titanium (its alloys) is used to make pipelines, tanks, valves, filters used in the distillation and transportation of acids and other chemically active substances. It is in demand when creating devices operating in conditions of elevated temperature indicators. Titanium compounds are used to make durable cutting tools, paints, plastics and paper, surgical instruments, implants, jewelry, finishing materials, and are used in the food industry. All directions are difficult to describe. Modern medicine, due to complete biological safety, often uses titanium metal. Price is the only factor that so far affects the breadth of application of this element. It is fair to say that titanium is the material of the future, by studying which humanity will passto a new stage of development.
