Contenido

El estado de oxidación +4 domina la química del titanio,[22]​ pero también son comunes los compuestos en el estado +3.[23]​ El titanio adopta habitualmente una geometría de coordinación octaédrica en sus compuestos, con la notable excepción tetraédrica del TiCl. Los compuestos de titanio(IV) presentan un alto grado de unión covalente debido su alto estado de oxidación.[24]​.

Oxides, sulfides and alkoxides

The most important oxide of titanium is titanium dioxide TiO, which exists mainly in anatase, brookite and rutile, all white diamagnetic solids.[15]​ In these compounds, polymeric structures are adopted, in which the Ti is surrounded by six oxide ligands that bind with other Ti centers.[25]​.

The term titanate is usually used to refer to titanium(IV) compounds, such as barium titanate (BaTiO).[26]​ With a structure like that of perovskite, this material has piezoelectric properties and is used as a transducer in the interconversion of sound and electricity.[8]​ Star sapphires and rubies obtain their asterism "Asterism (gemology)") due to the presence of impurities of carbon dioxide. titanium.[15]​.

Various reduced oxides of titanium are known. TiO, described as Ti(IV)-Ti(III), is a purple semiconductor produced by the reduction of TiO with hydrogen at high temperatures,[27]​ used industrially when it is required to cover surfaces with titanium dioxide vapor, since it evaporates as pure TiO while TiO evaporates as a mixture of oxides and other deposits that have a variable refractive index.[28]​ Other common oxides are titanium(III) oxide TiO and titanium(II) oxide. TiO.[29]​.

Titanium(IV) alkoxides, prepared by reacting TiCl with alcohols, are colorless compounds that convert to dioxide when reacting with water. They are industrially useful for depositing solid TiO through the sol-gel process. Titanium isopropoxide is used in the synthesis of organic compounds through Sharpless epoxidation.[30]​.

Nitrides and carbides

Titanium nitride (TiN) has a hardness equivalent to sapphire and silicon carbide (9.0 on the Mohs scale),[31]​ and is commonly used as a coating for industrial cutting tools.[32]​ It is also used as a decorative gold-colored coating and as a barrier metal in the manufacture of semiconductors.[33]​ Titanium carbide also has high hardness and is also used in cutting tools.[34]​.

Halides

Titanium tetrachloride TiCl[35]​ is a volatile liquid that causes hydrolysis in air, emitting a white smoke.[36]​ TiCl is produced by the Kroll method during the conversion of titanium minerals into titanium dioxide.[37]​ Its use is widespread in organic chemistry as Lewis acid.[38]​ Titanium tetraiodide (TiI) is generated during the van Arkel process for the production of high-quality titanium metal. purity.[39]​.

Titanium(III) and titanium(II) also form stable chlorides. A notable example is titanium trichloride), TiCl, used as a catalyst in the production of polyolefins and as a reducing agent in organic chemistry.[40]​.

Organometallic compounds

Titanium compounds play an important catalytic role in polymerization, so compounds with Ti-C bonds were intensively studied. The most common compounds of this type are titanocene dichloride") ((CH)TiCl), the Tebbe reagent") (CH)TiCHClAl(CH) and the Petasis reagent") (CpTi(CH)). Titanium also forms carbonyl compounds, such as titanocene dicarbonyl") (CH)Ti(CO).[41]​.

Titanium was discovered within a mineral in Cornwall, Great Britain, in 1791 by the clergyman and amateur geologist William Gregor, who at the time was the pastor of the parish of Creed.[42] He recognized the presence of a new element in ilmenite[5] when he found black sand in a stream in the parish of Manaccan and observed that the sand was attracted by a magnet.[42]​ His analysis of the sand determined the presence of two metal oxides: iron oxide (which caused the magnetic attraction) and a proportion of 45.25% of another white metallic oxide that he was not able to identify.[19]​ As this unidentified oxide contained a metal that did not meet the properties of any of the known elements, he reported his discovery to the Royal Geological Society of Cornwall and the German scientific journal Crell's Annalen, giving it the name manacanita.[42]​[43]​[44]​.

Around the same time Franz-Joseph Müller von Reichenstein produced a similar substance that he was also unable to identify.[5] Oxide was discovered again independently in 1795 by the Prussian chemist Martin Heinrich Klaproth in a rutile mineral in the Hungarian village of Boinik, in present-day Slovakia.[42][45] Klaproth found that the mineral contained a new element and He gave the name titanium after the titans of Greek mythology.[21]​ After learning of Gregor's previous discovery, he obtained a sample of manacanite and confirmed that it contained titanium.[46]​.

The known processes for the extraction of titanium from the various minerals that contain it are complicated and expensive. It is not possible to reduce the mineral in the usual way, by heating it in the presence of carbon, as this produces titanium carbide.[42] Pure (99.9%) metallic titanium was first obtained by Matthew La. Hunter") at the Rensselaer Polytechnic Institute by heating TiCl with sodium at a temperature of between 700 and 800 °C under great pressure,[47]​ a process known as the Hunter method.[4]​ Titanium metal was not used outside of laboratories until 1932, when William Justin Kroll proved that it could be produced by the reduction of titanium tetrachloride (TiCl) with calcium.[48]​ Eight years later he refined this process using magnesium. and sodium, in which it would be known as the Kroll method.[48]​ Although research continued later towards more efficient and cheaper production processes, the Kroll method continues to be used in the commercial production of this metal.[4][5]​.

High-purity titanium was also obtained in small quantities when Anton Eduard van Arkel and Jan Hendrik de Boer developed in 1925 what would be called the van Arkel-de Boer method, which reacted various metals with iodine to decompose the resulting iodides into filaments of pure metal.[49]

In the 1950s and 1960s, the Soviet Union pioneered the use of titanium in military and submarine applications,[47]​ such as in the Alfa and K-278 Komsomolets class submarines,[50]​ as part of programs related to the Cold War.[51]​ Also in the early 1950s, titanium began to be used extensively in military aviation, particularly in high-performance fighters such as the F-100 Super Sabre, the Lockheed A-12 and the SR-71.[52]​ Recognizing the strategic importance of titanium, the United States Department of Defense also began to support the first efforts to commercialize it.[53]​.

Throughout the Cold War, titanium was considered a strategic material by the United States Government, which maintained large reserves of this metal that were finally exhausted in the 2000s. to a consortium of two companies to develop a process for manufacturing titanium metal powder, with the purpose of using it in the creation of light and resistant objects for the aerospace, transportation and chemical industries. As of 2015, the titanium metal sponge was being produced in seven countries: China, Japan, Russia, Kazakhstan, the United States, Ukraine and India.

The production of titanium metal takes place in four main steps: reduction "Reduction (chemical)") of the titanium ore into a porous sponge form, melting of the sponge, primary manufacturing where it is converted into general-purpose products such as bars and plates, and finally secondary manufacturing of the final forms from the primary products.[59]​.

Since its production is not possible by reducing its dioxide,[10] titanium metal is obtained by reducing titanium tetrachloride TiCl with magnesium metal in what is known as the Kroll method. The complexity of this production process explains the high market value of titanium,[60]​ despite being a cheaper process than the Hunter method.[47]​ To produce the TiCl required by the Kroll method, a carbon-thermal reduction") is carried out in the presence of chlorine. In this process, the chlorine gas passes through a hot mixture of rutile or ilmenite in the presence of carbon. After extensive purification by fractional distillation, the TiCl is reduced with molten magnesium to 800 °C (1070 K) in an argon atmosphere.[8] The titanium metal thus obtained can subsequently be purified following the van Arkel-de Boer method), which involves a thermal decomposition of titanium tetraiodide.[49]​.

The most recent production process, called the FFC Cambridge process"),[61]​ uses titanium dioxide powder as raw material to obtain titanium metal. This process has fewer steps than the Kroll method, requires less time and allows the production of alloys by using certain mixtures of oxide powders.[62]​ The most common alloys of titanium are obtained by means of reduction, such as in the cases of cuprotitanium (reduction of rutile with added copper), of titanium. ferrocarbon (ilmenite reduced with coke in an electric boiler) and manganotitanium (rutile with manganese or manganese oxides):[63]​.

There are about 50 designated grades of titanium and its alloys, although only less than half of these are immediately commercially available.[64] The American Society for Testing and Materials (ASTM) recognizes 31 grades of titanium and its alloys, of which grades 1 through 4 are commercially pure. These four grades are differentiated by the variation in their breaking stress depending on the oxygen content, with grade 1 (0.18% oxygen) being the most ductile and grade 4 (0.40% oxygen) the least ductile.[15] The remaining grades are alloys, each one of them designed for a specific use, either for its ductility, strength, hardness, electrical resistance, resistance to deformation, resistance to corrosion or a combination of these properties.[65]​[66]​.

ASTM-covered grades and additional alloys are produced to meet SALE-AMS and MIL-T aerospace and military specifications, ESO standards, and country-specific specifications, as well as proprietary specifications for aerospace, military, medical, and industrial applications.[67]

Titanium powder is manufactured using a mass production process known as the Armstrong process,[68] similar to the batch process used in the Hunter method. In this Armstrong process, a stream of titanium tetrachloride gas is added to a stream of molten sodium metal. The sodium chloride and the resulting titanium particles are removed by filtering off the extra sodium. The titanium is then separated from the sodium chloride by washing with water. The sodium byproducts and chloride are recycled to be reused in this process and in the production of the initial titanium tetrachloride.[69]​.

In construction and manufacturing, all titanium welding must be done under inert atmospheres of argon or helium to avoid contamination with atmospheric gases such as oxygen, nitrogen or hydrogen. Otherwise, contamination can cause a variety of undesirable conditions, such as loss of ductility, which in turn can lead to reduced weld integrity and joint failure.[12]​.

Flat commercial products, such as plates and sheets, can be formed easily, but the processing of these shapes must take into account that the material has a "memory" and tends to return to its original shape, a fact that occurs especially in certain high-hardness alloys.[70][71]​.

Titanium cannot be welded without first being plated in a metal that is weldable,[72]​ and can be machined with the same type of equipment and processes as stainless steel.[12]​.

El titanio se emplea en las aleaciones de acero para reducir el tamaño del grano "Grano (mineral)") y como desoxidante, y en las de acero inoxidable para reducir su contenido de carbono.[3]​ Son frecuentes también las aleaciones con aluminio, vanadio, cobre, hierro, manganeso, molibdeno y otros metales.[7]​.

Pigments and additives

About 95% of the titanium ore extracted from the Earth is destined for refinement as titanium dioxide (), used as a permanent white pigment in paints, toothpastes and plastics.[18] It is also used in cement, in gems, to achieve opacity in paper,[73] and to increase the hardness in graphite fishing rods and golf clubs.

The powder is chemically inert, resists deterioration by sunlight and is very opaque. This allows you to give a bright white color to the brown or gray chemicals that make up most household plastics.[5]​ Paint made with titanium dioxide has good resistance to extreme temperatures, and withstands marine environments.[5]​ Pure titanium dioxide has a very high refractive index and a greater optical dispersion than diamond.[10]​ In addition to being an important pigment, it is also generally used in sunscreens.[10]​.

Aerospace and nautical applications

Thanks to their high breakdown stress to density ratio,[8]​ high corrosion resistance,[4]​ resistance to fatigue and cracks[74]​ and the ability to withstand moderately high temperatures without deforming, titanium alloys are commonly used in aircraft, vehicle armor, ships, spacecraft and missiles.[4][5]​ For these applications, titanium alloys with aluminum, zirconium, nickel and vanadium, among others, are used. elements.[75] Nearly two-thirds of all titanium metal produced is used in aircraft engines and structures, but it is also used in various other components such as critical structural parts, landing gears, exhaust ducts, and hydraulic systems.[76] The SR-71 Blackbird aircraft was one of the first aircraft to make extensive use of titanium as part of its structure, leading to the use of this material in modern aircraft. Estimates indicate that about 59 t are used in the Boeing 777, 45 t in the Boeing 747, 18 t in the Boeing 737, 32 t in the Airbus A340, 18 t in the Airbus A330 and 12 t in the Airbus A320. The Airbus A380 uses up to about 77 t, including about 11 t in its engines.[77]​ Regarding engine applications, titanium is used in rotors&action=edit&redlink=1 "Rotor (turbine) (not yet written)"), compressors "Compressor (machine)") and hydraulic system components. Titanium alloys 6AL-4V") account for almost 50% of all types of alloys used in aeronautical applications.[78]​ Thanks to its high resistance to corrosion by seawater, titanium is used in the manufacture of transmission shafts and ropes "Cabo (nautical)"), in heat exchangers in desalination plants, in seawater coolers in aquariums "Aquarium (vessel)"), fishing lines and hooks, and in divers' knives.[4] It is also used to manufacture casings and other components of marine surveillance and observation devices for scientific and military use. The former Soviet Union developed techniques for building submarines with hulls made of titanium alloy, and for forging titanium in vacuum tubes.[75]​.

Industrial applications

Welded pipes and certain titanium equipment, such as heat exchangers, tanks, waste vessels and valves, are used in the chemical and petrochemical industries, primarily due to their corrosion resistance. Certain specific alloys are used in drilling and iron and steel applications for their hardness, corrosion resistance, or a combination of the two factors. The paper industry uses titanium in processing equipment exposed to corrosive media such as chlorine gases.[79] Other industrial applications of titanium are ultrasonic welding, wave welding,[80] and sputtering.[81] Titanium tetrachloride TiCl is an important intermediate in obtaining titanium dioxide TiO is used in Ziegler-Natta, and is also used in the manufacture of iridescent glass and smoke screens.[10]​.

Consumer and architectural applications

Titanium metal is used in various automotive applications, particularly in motorsports and motorcycling, where weight reduction while maintaining strength and rigidity is a critical factor.[82]​.

This metal is generally too expensive to be commercially lucrative in the general market, except in high-end products. Some Chevrolet Corvette models included "Exhaust System (Engine)" exhaust pipes made of titanium,[83][84]​ and the Corvette Z06's supercharged engine uses solid, lightweight titanium inlet valves for greater heat resistance.[85]​.

Titanium is also used in many sports utensils, such as tennis rackets, golf clubs, lacrosse stick handles, grills for cricket, hockey, lacrosse and American football helmets, and bicycle frames and components.[86] Titanium alloys can also be used in eyeglass frames, increasing their cost but achieving a weight reduction and avoiding possible skin allergies. Many camping equipment is made of titanium, including cooking utensils, flashlights and spears, which are more expensive than traditional steel and aluminum utensils but offer lower weight without loss of hardness and strength. Titanium is also used in the manufacture of horseshoes, which are lighter and more durable than steel ones.[87]​.

Due to the advancement in metal manufacturing techniques and the lower weight compared to more traditional metals, the use of titanium in the manufacture of firearms is increasingly widespread.[88]​ For these same reasons it is also used in the manufacture of the casings of certain models of laptop computers.[89]​ Titanium has also sometimes been used in architectural applications. The 40 m high memorial to Yuri Gagarin in Moscow is made of titanium due to the metal's color and its association with the aerospace industry.[90]​.

El Museo Guggenheim de Bilbao y la Cerritos Millennium Library en Cerritos, California, fueron los primeros edificios en Europa y Norteamérica respectivamente en construirse con una cubierta de paneles de titanio.[76]​ Otras construcciones con cubiertas de titanio son el edificio Frederic C. Hamilton en Denver, Colorado[91]​ y el Monumento a los Conquistadores del Espacio de 107 m de altura en Moscú.[92]​.

Jeweler's

The use of titanium in jewelry designs is common, thanks to its durability and inert properties that make this metal a good choice to avoid possible allergies and resist water.[87] It can be used in the form of an alloy with gold, marketed as 24-karat gold, since 1% Ti in the alloy is not enough for this rating to be lowered. Pieces made with this alloy acquire a hardness equivalent to those of 14 carats, thus increasing their durability.[93]​.

The durability, lightness and resistance of this material make it very useful in the production of watch covers,[87]​ and some artists have worked with titanium in the production of sculptures, decorative objects and furniture.[94]​ Due to its inertness and ability to acquire various colors, titanium is a common metal in body piercings.[95]​ The different colors of these are obtained through anodization, varying the thickness of the outer layer of rust.[96]​.

Its use on non-legal tender "Currency (currency)" coins and commemorative medals is somewhat less common. As examples, in 1999 Gibraltar made public the first titanium coin, in celebration of the new millennium, and the Australian Gold Coast Titans rugby team awarded its player of the year a pure titanium medal.[97]​.

medical applications

Titanium has multiple medical applications thanks to its biocompatibility, including surgical tools and medical implants.[42]​ For these purposes, titanium is usually used in alloys with between 4% and 6% aluminum and 4% vanadium.[98]​.

Thanks to this inherent ease of integrating into the bones, it is very useful in dental and orthopedic implants, which can have a useful life of up to 30 years.[42] These implants benefit from the low elastic constant that titanium has to resemble that of bones as much as possible. This ensures that the loads are distributed more equally between the bones and the implant, achieving a lower rate of degradation in the bones and reducing the possibility of medical complications related to the implant itself. However, the rigidity of titanium alloys is twice that of bone, so adjacent bones receive less load and may suffer deterioration.[99]​.

As a non-ferromagnetic metal, patients with titanium implants can be safely examined using magnetic resonance imaging. Preparing titanium for use in body implants requires it to be treated under a high-temperature plasma arc to remove surface atoms, exposing the underlying titanium atoms in the process.[42]​.

Nuclear waste storage

The corrosion resistance of titanium led to containers made of this material being investigated for use in the long-term storage of nuclear waste, determining that it is possible to manufacture containers that can last up to 100,000 years as long as the process meets a series of manufacturing conditions determined to reduce possible defects.[100] It can also be used as an anti-drip protector on other types of containers to help contain the waste stored in them.[101]​.

Titanium is not toxic even in large doses and does not play any natural biological role in the human body.[21] It is estimated that humans ingest an amount of 0.8 milligrams of titanium each day, although it is mostly expelled later without being absorbed by the body.[21] However, titanium does have a tendency to accumulate biologically in tissues that contain silica,[102] and a 2011 study indicated a possible connection between titanium and the syndrome. yellow nail").[103]​ There are also indications of the existence of an unknown mechanism in some plants that would use titanium to stimulate the production of carbohydrates and help them grow, which would explain why many plants contain between 1 and 2 parts per million of titanium, reaching up to 80 parts per million in the genera Equisetum and Urtica.[21]​ The fungal species Marasmius oreades and Hypholoma capnoides can bioconvert titanium in titanium-contaminated soils.[104]​ In the form of powder or chips, titanium metal presents a significant fire risk, and when heated in air there is also an explosion risk.[105]​ Water- and carbon dioxide-based fire extinguishing methods are not effective with burning titanium, so the use of class D extinguishers is required to deal with fires caused by this metal.[5]​ When used in the production or handling of chlorine, care should be taken to use titanium only in places where it is not exposed to dry chlorine gas, as it can cause a fire.[106]​ Titanium can also burn when it comes into contact with a surface that has not yet achieved the oxidation state with liquid oxygen.[107]​.

Contenido

El estado de oxidación +4 domina la química del titanio,[22]​ pero también son comunes los compuestos en el estado +3.[23]​ El titanio adopta habitualmente una geometría de coordinación octaédrica en sus compuestos, con la notable excepción tetraédrica del TiCl. Los compuestos de titanio(IV) presentan un alto grado de unión covalente debido su alto estado de oxidación.[24]​.

Oxides, sulfides and alkoxides

The most important oxide of titanium is titanium dioxide TiO, which exists mainly in anatase, brookite and rutile, all white diamagnetic solids.[15]​ In these compounds, polymeric structures are adopted, in which the Ti is surrounded by six oxide ligands that bind with other Ti centers.[25]​.

The term titanate is usually used to refer to titanium(IV) compounds, such as barium titanate (BaTiO).[26]​ With a structure like that of perovskite, this material has piezoelectric properties and is used as a transducer in the interconversion of sound and electricity.[8]​ Star sapphires and rubies obtain their asterism "Asterism (gemology)") due to the presence of impurities of carbon dioxide. titanium.[15]​.

Various reduced oxides of titanium are known. TiO, described as Ti(IV)-Ti(III), is a purple semiconductor produced by the reduction of TiO with hydrogen at high temperatures,[27]​ used industrially when it is required to cover surfaces with titanium dioxide vapor, since it evaporates as pure TiO while TiO evaporates as a mixture of oxides and other deposits that have a variable refractive index.[28]​ Other common oxides are titanium(III) oxide TiO and titanium(II) oxide. TiO.[29]​.

Titanium(IV) alkoxides, prepared by reacting TiCl with alcohols, are colorless compounds that convert to dioxide when reacting with water. They are industrially useful for depositing solid TiO through the sol-gel process. Titanium isopropoxide is used in the synthesis of organic compounds through Sharpless epoxidation.[30]​.

Nitrides and carbides

Titanium nitride (TiN) has a hardness equivalent to sapphire and silicon carbide (9.0 on the Mohs scale),[31]​ and is commonly used as a coating for industrial cutting tools.[32]​ It is also used as a decorative gold-colored coating and as a barrier metal in the manufacture of semiconductors.[33]​ Titanium carbide also has high hardness and is also used in cutting tools.[34]​.

Halides

Titanium tetrachloride TiCl[35]​ is a volatile liquid that causes hydrolysis in air, emitting a white smoke.[36]​ TiCl is produced by the Kroll method during the conversion of titanium minerals into titanium dioxide.[37]​ Its use is widespread in organic chemistry as Lewis acid.[38]​ Titanium tetraiodide (TiI) is generated during the van Arkel process for the production of high-quality titanium metal. purity.[39]​.

Titanium(III) and titanium(II) also form stable chlorides. A notable example is titanium trichloride), TiCl, used as a catalyst in the production of polyolefins and as a reducing agent in organic chemistry.[40]​.

Organometallic compounds

Titanium compounds play an important catalytic role in polymerization, so compounds with Ti-C bonds were intensively studied. The most common compounds of this type are titanocene dichloride") ((CH)TiCl), the Tebbe reagent") (CH)TiCHClAl(CH) and the Petasis reagent") (CpTi(CH)). Titanium also forms carbonyl compounds, such as titanocene dicarbonyl") (CH)Ti(CO).[41]​.

Titanium was discovered within a mineral in Cornwall, Great Britain, in 1791 by the clergyman and amateur geologist William Gregor, who at the time was the pastor of the parish of Creed.[42] He recognized the presence of a new element in ilmenite[5] when he found black sand in a stream in the parish of Manaccan and observed that the sand was attracted by a magnet.[42]​ His analysis of the sand determined the presence of two metal oxides: iron oxide (which caused the magnetic attraction) and a proportion of 45.25% of another white metallic oxide that he was not able to identify.[19]​ As this unidentified oxide contained a metal that did not meet the properties of any of the known elements, he reported his discovery to the Royal Geological Society of Cornwall and the German scientific journal Crell's Annalen, giving it the name manacanita.[42]​[43]​[44]​.

Around the same time Franz-Joseph Müller von Reichenstein produced a similar substance that he was also unable to identify.[5] Oxide was discovered again independently in 1795 by the Prussian chemist Martin Heinrich Klaproth in a rutile mineral in the Hungarian village of Boinik, in present-day Slovakia.[42][45] Klaproth found that the mineral contained a new element and He gave the name titanium after the titans of Greek mythology.[21]​ After learning of Gregor's previous discovery, he obtained a sample of manacanite and confirmed that it contained titanium.[46]​.

The known processes for the extraction of titanium from the various minerals that contain it are complicated and expensive. It is not possible to reduce the mineral in the usual way, by heating it in the presence of carbon, as this produces titanium carbide.[42] Pure (99.9%) metallic titanium was first obtained by Matthew La. Hunter") at the Rensselaer Polytechnic Institute by heating TiCl with sodium at a temperature of between 700 and 800 °C under great pressure,[47]​ a process known as the Hunter method.[4]​ Titanium metal was not used outside of laboratories until 1932, when William Justin Kroll proved that it could be produced by the reduction of titanium tetrachloride (TiCl) with calcium.[48]​ Eight years later he refined this process using magnesium. and sodium, in which it would be known as the Kroll method.[48]​ Although research continued later towards more efficient and cheaper production processes, the Kroll method continues to be used in the commercial production of this metal.[4][5]​.

High-purity titanium was also obtained in small quantities when Anton Eduard van Arkel and Jan Hendrik de Boer developed in 1925 what would be called the van Arkel-de Boer method, which reacted various metals with iodine to decompose the resulting iodides into filaments of pure metal.[49]

In the 1950s and 1960s, the Soviet Union pioneered the use of titanium in military and submarine applications,[47]​ such as in the Alfa and K-278 Komsomolets class submarines,[50]​ as part of programs related to the Cold War.[51]​ Also in the early 1950s, titanium began to be used extensively in military aviation, particularly in high-performance fighters such as the F-100 Super Sabre, the Lockheed A-12 and the SR-71.[52]​ Recognizing the strategic importance of titanium, the United States Department of Defense also began to support the first efforts to commercialize it.[53]​.

Throughout the Cold War, titanium was considered a strategic material by the United States Government, which maintained large reserves of this metal that were finally exhausted in the 2000s. to a consortium of two companies to develop a process for manufacturing titanium metal powder, with the purpose of using it in the creation of light and resistant objects for the aerospace, transportation and chemical industries. As of 2015, the titanium metal sponge was being produced in seven countries: China, Japan, Russia, Kazakhstan, the United States, Ukraine and India.

The production of titanium metal takes place in four main steps: reduction "Reduction (chemical)") of the titanium ore into a porous sponge form, melting of the sponge, primary manufacturing where it is converted into general-purpose products such as bars and plates, and finally secondary manufacturing of the final forms from the primary products.[59]​.

Since its production is not possible by reducing its dioxide,[10] titanium metal is obtained by reducing titanium tetrachloride TiCl with magnesium metal in what is known as the Kroll method. The complexity of this production process explains the high market value of titanium,[60]​ despite being a cheaper process than the Hunter method.[47]​ To produce the TiCl required by the Kroll method, a carbon-thermal reduction") is carried out in the presence of chlorine. In this process, the chlorine gas passes through a hot mixture of rutile or ilmenite in the presence of carbon. After extensive purification by fractional distillation, the TiCl is reduced with molten magnesium to 800 °C (1070 K) in an argon atmosphere.[8] The titanium metal thus obtained can subsequently be purified following the van Arkel-de Boer method), which involves a thermal decomposition of titanium tetraiodide.[49]​.

The most recent production process, called the FFC Cambridge process"),[61]​ uses titanium dioxide powder as raw material to obtain titanium metal. This process has fewer steps than the Kroll method, requires less time and allows the production of alloys by using certain mixtures of oxide powders.[62]​ The most common alloys of titanium are obtained by means of reduction, such as in the cases of cuprotitanium (reduction of rutile with added copper), of titanium. ferrocarbon (ilmenite reduced with coke in an electric boiler) and manganotitanium (rutile with manganese or manganese oxides):[63]​.

There are about 50 designated grades of titanium and its alloys, although only less than half of these are immediately commercially available.[64] The American Society for Testing and Materials (ASTM) recognizes 31 grades of titanium and its alloys, of which grades 1 through 4 are commercially pure. These four grades are differentiated by the variation in their breaking stress depending on the oxygen content, with grade 1 (0.18% oxygen) being the most ductile and grade 4 (0.40% oxygen) the least ductile.[15] The remaining grades are alloys, each one of them designed for a specific use, either for its ductility, strength, hardness, electrical resistance, resistance to deformation, resistance to corrosion or a combination of these properties.[65]​[66]​.

ASTM-covered grades and additional alloys are produced to meet SALE-AMS and MIL-T aerospace and military specifications, ESO standards, and country-specific specifications, as well as proprietary specifications for aerospace, military, medical, and industrial applications.[67]

Titanium powder is manufactured using a mass production process known as the Armstrong process,[68] similar to the batch process used in the Hunter method. In this Armstrong process, a stream of titanium tetrachloride gas is added to a stream of molten sodium metal. The sodium chloride and the resulting titanium particles are removed by filtering off the extra sodium. The titanium is then separated from the sodium chloride by washing with water. The sodium byproducts and chloride are recycled to be reused in this process and in the production of the initial titanium tetrachloride.[69]​.

In construction and manufacturing, all titanium welding must be done under inert atmospheres of argon or helium to avoid contamination with atmospheric gases such as oxygen, nitrogen or hydrogen. Otherwise, contamination can cause a variety of undesirable conditions, such as loss of ductility, which in turn can lead to reduced weld integrity and joint failure.[12]​.

Flat commercial products, such as plates and sheets, can be formed easily, but the processing of these shapes must take into account that the material has a "memory" and tends to return to its original shape, a fact that occurs especially in certain high-hardness alloys.[70][71]​.

Titanium cannot be welded without first being plated in a metal that is weldable,[72]​ and can be machined with the same type of equipment and processes as stainless steel.[12]​.

El titanio se emplea en las aleaciones de acero para reducir el tamaño del grano "Grano (mineral)") y como desoxidante, y en las de acero inoxidable para reducir su contenido de carbono.[3]​ Son frecuentes también las aleaciones con aluminio, vanadio, cobre, hierro, manganeso, molibdeno y otros metales.[7]​.

Pigments and additives

About 95% of the titanium ore extracted from the Earth is destined for refinement as titanium dioxide (), used as a permanent white pigment in paints, toothpastes and plastics.[18] It is also used in cement, in gems, to achieve opacity in paper,[73] and to increase the hardness in graphite fishing rods and golf clubs.

The powder is chemically inert, resists deterioration by sunlight and is very opaque. This allows you to give a bright white color to the brown or gray chemicals that make up most household plastics.[5]​ Paint made with titanium dioxide has good resistance to extreme temperatures, and withstands marine environments.[5]​ Pure titanium dioxide has a very high refractive index and a greater optical dispersion than diamond.[10]​ In addition to being an important pigment, it is also generally used in sunscreens.[10]​.

Aerospace and nautical applications

Thanks to their high breakdown stress to density ratio,[8]​ high corrosion resistance,[4]​ resistance to fatigue and cracks[74]​ and the ability to withstand moderately high temperatures without deforming, titanium alloys are commonly used in aircraft, vehicle armor, ships, spacecraft and missiles.[4][5]​ For these applications, titanium alloys with aluminum, zirconium, nickel and vanadium, among others, are used. elements.[75] Nearly two-thirds of all titanium metal produced is used in aircraft engines and structures, but it is also used in various other components such as critical structural parts, landing gears, exhaust ducts, and hydraulic systems.[76] The SR-71 Blackbird aircraft was one of the first aircraft to make extensive use of titanium as part of its structure, leading to the use of this material in modern aircraft. Estimates indicate that about 59 t are used in the Boeing 777, 45 t in the Boeing 747, 18 t in the Boeing 737, 32 t in the Airbus A340, 18 t in the Airbus A330 and 12 t in the Airbus A320. The Airbus A380 uses up to about 77 t, including about 11 t in its engines.[77]​ Regarding engine applications, titanium is used in rotors&action=edit&redlink=1 "Rotor (turbine) (not yet written)"), compressors "Compressor (machine)") and hydraulic system components. Titanium alloys 6AL-4V") account for almost 50% of all types of alloys used in aeronautical applications.[78]​ Thanks to its high resistance to corrosion by seawater, titanium is used in the manufacture of transmission shafts and ropes "Cabo (nautical)"), in heat exchangers in desalination plants, in seawater coolers in aquariums "Aquarium (vessel)"), fishing lines and hooks, and in divers' knives.[4] It is also used to manufacture casings and other components of marine surveillance and observation devices for scientific and military use. The former Soviet Union developed techniques for building submarines with hulls made of titanium alloy, and for forging titanium in vacuum tubes.[75]​.

Industrial applications

Welded pipes and certain titanium equipment, such as heat exchangers, tanks, waste vessels and valves, are used in the chemical and petrochemical industries, primarily due to their corrosion resistance. Certain specific alloys are used in drilling and iron and steel applications for their hardness, corrosion resistance, or a combination of the two factors. The paper industry uses titanium in processing equipment exposed to corrosive media such as chlorine gases.[79] Other industrial applications of titanium are ultrasonic welding, wave welding,[80] and sputtering.[81] Titanium tetrachloride TiCl is an important intermediate in obtaining titanium dioxide TiO is used in Ziegler-Natta, and is also used in the manufacture of iridescent glass and smoke screens.[10]​.

Consumer and architectural applications

Titanium metal is used in various automotive applications, particularly in motorsports and motorcycling, where weight reduction while maintaining strength and rigidity is a critical factor.[82]​.

This metal is generally too expensive to be commercially lucrative in the general market, except in high-end products. Some Chevrolet Corvette models included "Exhaust System (Engine)" exhaust pipes made of titanium,[83][84]​ and the Corvette Z06's supercharged engine uses solid, lightweight titanium inlet valves for greater heat resistance.[85]​.

Titanium is also used in many sports utensils, such as tennis rackets, golf clubs, lacrosse stick handles, grills for cricket, hockey, lacrosse and American football helmets, and bicycle frames and components.[86] Titanium alloys can also be used in eyeglass frames, increasing their cost but achieving a weight reduction and avoiding possible skin allergies. Many camping equipment is made of titanium, including cooking utensils, flashlights and spears, which are more expensive than traditional steel and aluminum utensils but offer lower weight without loss of hardness and strength. Titanium is also used in the manufacture of horseshoes, which are lighter and more durable than steel ones.[87]​.

Due to the advancement in metal manufacturing techniques and the lower weight compared to more traditional metals, the use of titanium in the manufacture of firearms is increasingly widespread.[88]​ For these same reasons it is also used in the manufacture of the casings of certain models of laptop computers.[89]​ Titanium has also sometimes been used in architectural applications. The 40 m high memorial to Yuri Gagarin in Moscow is made of titanium due to the metal's color and its association with the aerospace industry.[90]​.

El Museo Guggenheim de Bilbao y la Cerritos Millennium Library en Cerritos, California, fueron los primeros edificios en Europa y Norteamérica respectivamente en construirse con una cubierta de paneles de titanio.[76]​ Otras construcciones con cubiertas de titanio son el edificio Frederic C. Hamilton en Denver, Colorado[91]​ y el Monumento a los Conquistadores del Espacio de 107 m de altura en Moscú.[92]​.

Jeweler's

The use of titanium in jewelry designs is common, thanks to its durability and inert properties that make this metal a good choice to avoid possible allergies and resist water.[87] It can be used in the form of an alloy with gold, marketed as 24-karat gold, since 1% Ti in the alloy is not enough for this rating to be lowered. Pieces made with this alloy acquire a hardness equivalent to those of 14 carats, thus increasing their durability.[93]​.

The durability, lightness and resistance of this material make it very useful in the production of watch covers,[87]​ and some artists have worked with titanium in the production of sculptures, decorative objects and furniture.[94]​ Due to its inertness and ability to acquire various colors, titanium is a common metal in body piercings.[95]​ The different colors of these are obtained through anodization, varying the thickness of the outer layer of rust.[96]​.

Its use on non-legal tender "Currency (currency)" coins and commemorative medals is somewhat less common. As examples, in 1999 Gibraltar made public the first titanium coin, in celebration of the new millennium, and the Australian Gold Coast Titans rugby team awarded its player of the year a pure titanium medal.[97]​.

medical applications

Titanium has multiple medical applications thanks to its biocompatibility, including surgical tools and medical implants.[42]​ For these purposes, titanium is usually used in alloys with between 4% and 6% aluminum and 4% vanadium.[98]​.

Thanks to this inherent ease of integrating into the bones, it is very useful in dental and orthopedic implants, which can have a useful life of up to 30 years.[42] These implants benefit from the low elastic constant that titanium has to resemble that of bones as much as possible. This ensures that the loads are distributed more equally between the bones and the implant, achieving a lower rate of degradation in the bones and reducing the possibility of medical complications related to the implant itself. However, the rigidity of titanium alloys is twice that of bone, so adjacent bones receive less load and may suffer deterioration.[99]​.

As a non-ferromagnetic metal, patients with titanium implants can be safely examined using magnetic resonance imaging. Preparing titanium for use in body implants requires it to be treated under a high-temperature plasma arc to remove surface atoms, exposing the underlying titanium atoms in the process.[42]​.

Nuclear waste storage

The corrosion resistance of titanium led to containers made of this material being investigated for use in the long-term storage of nuclear waste, determining that it is possible to manufacture containers that can last up to 100,000 years as long as the process meets a series of manufacturing conditions determined to reduce possible defects.[100] It can also be used as an anti-drip protector on other types of containers to help contain the waste stored in them.[101]​.

Titanium is not toxic even in large doses and does not play any natural biological role in the human body.[21] It is estimated that humans ingest an amount of 0.8 milligrams of titanium each day, although it is mostly expelled later without being absorbed by the body.[21] However, titanium does have a tendency to accumulate biologically in tissues that contain silica,[102] and a 2011 study indicated a possible connection between titanium and the syndrome. yellow nail").[103]​ There are also indications of the existence of an unknown mechanism in some plants that would use titanium to stimulate the production of carbohydrates and help them grow, which would explain why many plants contain between 1 and 2 parts per million of titanium, reaching up to 80 parts per million in the genera Equisetum and Urtica.[21]​ The fungal species Marasmius oreades and Hypholoma capnoides can bioconvert titanium in titanium-contaminated soils.[104]​ In the form of powder or chips, titanium metal presents a significant fire risk, and when heated in air there is also an explosion risk.[105]​ Water- and carbon dioxide-based fire extinguishing methods are not effective with burning titanium, so the use of class D extinguishers is required to deal with fires caused by this metal.[5]​ When used in the production or handling of chlorine, care should be taken to use titanium only in places where it is not exposed to dry chlorine gas, as it can cause a fire.[106]​ Titanium can also burn when it comes into contact with a surface that has not yet achieved the oxidation state with liquid oxygen.[107]​.