Titanium

Physical properties As a metal, titanium is recognized for its high strength-to-weight ratio. It is a strong metal with low density that is quite ductile (especially in an oxygen-free environment), lustrous, and metallic-white in color. Due to its relatively high melting point (1,668 °C or 3,034 °F) it has sometimes been described as a refractory metal, but this is not the case. It is paramagnetic and has fairly low electrical and thermal conductivity compared to other metals. Commercially pure (99.2% pure) grades of titanium have ultimate tensile strength of about 434 MPa (63,000 psi), equal to that of common, low-grade steel alloys, but are less dense. Titanium is 60% denser than aluminium, but more than twice as strong However, titanium loses strength when heated above . Titanium is not as hard as some grades of heat-treated steel; it is non-magnetic and a poor conductor of heat and electricity. Machining requires precautions, because the material can gall unless sharp tools and proper cooling methods are used. Like steel structures, those made from titanium have a fatigue limit that guarantees longevity in some applications. The specific heat of the α form increases dramatically as it is heated to this transition temperature but then falls and remains fairly constant for the β form regardless of temperature. Like aluminium and magnesium, the surface of titanium metal and its alloys oxidizes immediately upon exposure to air to form a thin non-porous passivation layer that protects the bulk metal from further oxidation or corrosion. Titanium is capable of withstanding attack by dilute sulfuric and hydrochloric acids at room temperature, chloride solutions, and most organic acids. Titanium burns in normal air at temperatures lower than its melting point, so melting the metal is possible only in an inert atmosphere or vacuum. Occurrence Titanium is the ninth-most abundant element in Earth's crust (0.63% by mass) Of the 801 types of igneous rocks analyzed by the United States Geological Survey, 784 contained titanium. Its proportion in soils is approximately 0.5–1.5%. Akaogiite is an extremely rare mineral consisting of titanium dioxide. Of these minerals, only rutile and ilmenite have economic importance, yet even they are difficult to find in high concentrations. About 6.0 and 0.7 million tonnes of those minerals were mined in 2011, respectively. Titanium is contained in meteorites, and it has been detected in the Sun and in M-type stars Rocks brought back from the Moon during the Apollo 17 mission are composed of 12.1% TiO2. but it has been identified in nanocrystals on the Moon. Isotopes Naturally occurring titanium is composed of five stable isotopes: Ti, Ti, Ti, Ti, and Ti, with Ti being the most abundant (73.8% natural abundance). Twenty-three radioisotopes have been characterized, the most stable of which are Ti with a half-life of 63 years; Ti, 184.8 minutes; Ti, 5.76 minutes; and Ti, 1.7 minutes. All other radioactive isotopes have half-lives less than 33 seconds, with the majority less than half a second. The isotopes of titanium range from Ti to Ti. The primary decay mode for isotopes lighter than Ti is positron emission (with the exception of Ti, which undergoes electron capture), leading to isotopes of scandium, and the primary mode for isotopes heavier than Ti is beta emission, leading to isotopes of vanadium. Titanium becomes radioactive upon bombardment with deuterons, emitting mainly positrons and hard gamma rays. == Compounds ==

The +4 oxidation state dominates titanium chemistry, but compounds in the +3 oxidation state are also numerous. Commonly, titanium adopts an octahedral coordination geometry in its complexes, but tetrahedral TiCl4 is a notable exception. Because of its high oxidation state, titanium(IV) compounds exhibit a high degree of covalent bonding. The term titanates usually refers to titanium(IV) compounds, as represented by barium titanate (BaTiO3). With a perovskite structure, this material exhibits piezoelectric properties and is used as a transducer in the interconversion of sound and electricity. and is used industrially when surfaces need to be vapor-coated with titanium dioxide: it evaporates as pure TiO, whereas TiO2 evaporates as a mixture of oxides and deposits coatings with variable refractive index. Also known is Ti2O3, with the corundum structure, and TiO, with the rock salt structure, although often nonstoichiometric. The alkoxides of titanium(IV), prepared by treating TiCl4 with alcohols, are colorless compounds that convert to the dioxide on reaction with water. They are industrially useful for depositing solid TiO2 via the sol-gel process. Titanium isopropoxide is used in the synthesis of chiral organic compounds via the Sharpless epoxidation. Titanium forms a variety of sulfides, but only TiS2 has attracted significant interest. It adopts a layered structure and was used as a cathode in the development of lithium batteries. Because Ti(IV) is a "hard cation", the sulfides of titanium are unstable and tend to hydrolyze to the oxide with release of hydrogen sulfide. Nitrides and carbides Titanium nitride (TiN) is a refractory solid exhibiting extreme hardness, thermal/electrical conductivity, and a high melting point. TiN has a hardness equivalent to sapphire and carborundum (9.0 on the Mohs scale), and is often used to coat cutting tools, such as drill bits. It is also used as a gold-colored decorative finish and as a barrier layer in semiconductor fabrication. Titanium carbide (TiC), which is also very hard, is found in cutting tools and coatings. Halides . Titanium tetrachloride (titanium(IV) chloride, TiCl4) is a colorless volatile liquid (commercial samples are yellowish) that, in air, hydrolyzes with spectacular emission of white clouds. Via the Kroll process, TiCl4 is used in the conversion of titanium ores to titanium metal. Titanium tetrachloride is also used to make titanium dioxide, e.g., for use in white paint. It is widely used in organic chemistry as a Lewis acid, for example in the Mukaiyama aldol condensation. In the van Arkel–de Boer process, titanium tetraiodide (TiI4) is generated in the production of high purity titanium metal. Titanium(III) and titanium(II) also form stable chlorides. A notable example is titanium(III) chloride (TiCl3), which is used as a catalyst for production of polyolefins (see Ziegler–Natta catalyst) and a reducing agent in organic chemistry. Organometallic complexes Owing to the important role of titanium compounds as polymerization catalyst, compounds with Ti-C bonds have been intensively studied. The most common organotitanium complex is titanocene dichloride ((C5H5)2TiCl2). Related compounds include Tebbe's reagent and Petasis reagent. Titanium forms carbonyl complexes, e.g. (C5H5)2Ti(CO)2. == History ==

named titanium for the Titans of Greek mythology. Titanium was discovered in 1791 by the clergyman and geologist William Gregor as an inclusion of a mineral in Cornwall, Great Britain. Realizing that the unidentified oxide contained a metal that did not match any known element, in 1791 Gregor reported his findings in both German and French science journals: ''Crell's Annalen and Observations et Mémoires sur la Physique''. He named this oxide manaccanite. Around the same time, Franz-Joseph Müller von Reichenstein produced a similar substance, but could not identify it. The currently known processes for extracting titanium from its various ores are laborious and costly; it is not possible to reduce the ore by heating with carbon (as in iron smelting) because titanium combines with the carbon to produce titanium carbide. Pure metallic titanium (99.9%) was first prepared in 1910 by Matthew A. Hunter at Rensselaer Polytechnic Institute by heating TiCl4 with sodium at under great pressure in a batch process known as the Hunter process. Eight years later he refined this process with magnesium and with sodium in what became known as the Kroll process. In the 1950s and 1960s, the Soviet Union pioneered the use of titanium in military and submarine applications as part of programs related to the Cold War. Starting in the early 1950s, titanium came into use extensively in military aviation, particularly in high-performance jets, starting with aircraft such as the F-100 Super Sabre and Lockheed A-12 and SR-71. Throughout the Cold War period, titanium was considered a strategic material by the U.S. government, and a large stockpile of titanium sponge (a porous form of the pure metal) was maintained by the Defense National Stockpile Center, until the stockpile was dispersed in the 2000s. Even so, the U.S. government annually allocates 15,000metric tons of titanium sponge as potential acquisitions for the stockpile. ==Production==

Titanium production is largely divided into three measured categories: manufacture of porous titanium metal "sponge", titanium oxide pigment, and titanium mineral concentrates used for the production of sponge, pigment, metal ingots, and other titanium products such as coatings. These concentrates are largely made up of the mineral ilmenite, but also include anatase, natural and synthetic rutile, tailings, slag, and leucoxene. As of 2024, the largest producers of titanium mineral concentrates were China, Mozambique, and South Africa. Most of the world's titanium is produced in China. The United States Geological Survey's 2025 report on mineral commodities estimated that out of the of titanium sponge produced globally in 2024, 220,000 (69%) were produced in China, with the second-largest producer being Japan (which produced 55,000metric tons in the same year, 17% of the total). Japan was the largest exporter of titanium sponge in 2024, but did not produce any titanium minerals on its own. Production statistics on titanium dioxide pigment are not as clear-cut, but estimates placed the maximum capacity on global pigment production at in 2024. It is not used at scale. The chloride process produces titanium tetrachloride through treatment of rutile ore with chlorine and carbon at high heat, The sulfate process uses sulfuric acid (H2SO4) to leach titanium from ilmenite ore (FeTiO3), producing titanyl sulfate (). This sulfate is broken into two hydrates, and , through addition of water, and this water is removed by adding heat, which produces titanium dioxide as the end product. Purification processes Hunter process The Hunter process was the first industrial process to produce pure metallic titanium. It was invented in 1910 by Matthew A. Hunter, a chemist born in New Zealand who worked in the United States. The process involves reducing titanium tetrachloride (TiCl4) with sodium (Na) in a batch reactor with an inert atmosphere at a temperature of 1,000 °C. Dilute hydrochloric acid is then used to leach the salt from the product. :TiCl4(g) + 4 Na(l) → 4 NaCl(l) + Ti(s) Kroll process The processing of titanium metal occurs in four major steps: reduction of titanium ore into "sponge", a porous form; melting of sponge, or sponge plus a master alloy to form an ingot; primary fabrication, where an ingot is converted into general mill products such as billet, bar, plate, sheet, strip, and tube; and secondary fabrication of finished shapes from mill products. Because it cannot be readily produced by reduction of titanium dioxide, despite the Kroll process being less expensive than the Hunter process. It is a closed-loop process that involves thermal decomposition of titanium tetraiodide. This same process is used to purify other metals, such as thorium, hafnium, and zirconium, that is similar to the batch production Hunter process. A stream of titanium tetrachloride gas is added to a stream of molten sodium; the products (sodium chloride salt and titanium particles) are filtered from the extra sodium. Titanium is then separated from the salt by water washing. Both the sodium and chlorine are recycled to produce and process more titanium tetrachloride. Other processes The titanium tetrachloride used as an intermediate in both the Hunter and Kroll process is a volatile and corrosive liquid, and is thus hazardous to work with. The processes involving the tetrachloride, both its formation and the vacuum distillation processes used to purify the final material, are slow, and have prompted development of other techniques. Methods for electrolytic production of Ti metal from using molten salt electrolytes have been proposed starting in the 1990s, While some metals such as nickel and copper can be refined by electrowinning at room temperature, titanium must be in the molten state, which is likely to damage the refractory lining of a reaction vessel. Zhang and colleagues concluded in 2017 that despite industry interests in finding new ways to manufacture titanium metal, no method had yet been developed to commercially replace the Kroll process. One manufacturer in Virginia has developed a method to recycle scrap titanium metal back into powder, though their scale remains small, having the goal of producing only 125 tons of titanium per year as of 2025. Fabrication All welding of titanium must be done in an inert atmosphere of argon or helium to shield it from contamination with atmospheric gases (oxygen, nitrogen, and hydrogen). Titanium is very difficult to solder directly, and hence a solderable metal or alloy such as steel is coated on titanium prior to soldering. Titanium metal can be machined with the same equipment and the same processes as stainless steel. About fifty grades of titanium alloys are designed and currently used, although only a couple of dozen are readily available commercially. The ASTM International recognizes 31 grades of titanium metal and alloys, of which grades one through four are commercially pure (unalloyed). Those four vary in tensile strength as a function of oxygen content, with grade 1 being the most ductile (lowest tensile strength with an oxygen content of 0.18%), and grade 4 the least ductile (highest tensile strength with an oxygen content of 0.40%). In addition to the ASTM specifications, titanium alloys are also produced to meet aerospace and military specifications (SAE-AMS, MIL-T), ISO standards, and country-specific specifications, as well as proprietary end-user specifications for aerospace, military, medical, and industrial applications. Forming and forging Commercially pure flat product (sheet, plate) can be formed readily, but processing must take into account of the tendency of the metal to springback. This is especially true of certain high-strength alloys. Exposure to the oxygen in air at the elevated temperatures used in forging results in formation of a brittle oxygen-rich metallic surface layer called "alpha case" that worsens the fatigue properties, so it must be removed by milling, etching, or electrochemical treatment. The working of titanium may include friction welding, cryo-forging, and vacuum arc remelting. ==Applications==

Titanium is used in steel as an alloying element (ferro-titanium) to reduce grain size and as a deoxidizer, and in stainless steel to reduce carbon content. Titanium mill products (sheet, plate, bar, wire, forgings, castings) find application in industrial, aerospace, recreational, and emerging markets. Powdered titanium is used in pyrotechnics as a source of bright-burning particles. Pigments, additives, and coatings is the most commonly used compound of titanium. It is also used in cement, in gemstones, and as an optical opacifier in paper. pigment is chemically inert, resists fading in sunlight, and is very opaque: it imparts a pure and brilliant white color to the brown or grey chemicals that form the majority of household plastics. and ability to withstand moderately high temperatures without creeping, they are used in aircraft, armor plating, naval ships, spacecraft, and missiles. The Lockheed A-12 and the SR-71 "Blackbird" were two of the first aircraft frames where titanium was used, paving the way for much wider use in modern military and commercial aircraft. A large amount of titanium mill products are used in the production of many aircraft, such as (following values are amount of raw mill products used, only a fraction of this ends up in the finished aircraft): 116 metric tons are used in the Boeing 787, 77 in the Airbus A380, 59 in the Boeing 777, 45 in the Boeing 747, 32 in the Airbus A340, 18 in the Boeing 737, 18 in the Airbus A330, and 12 in the Airbus A320. In aero engine applications, titanium is used for rotors, compressor blades, hydraulic system components, and nacelles. An early use in jet engines was for the Orenda Iroquois in the 1950s. Because titanium is resistant to corrosion by sea water, it is used to make propeller shafts, rigging, heat exchangers in desalination plants, forging titanium in huge vacuum tubes. Industrial Welded titanium pipe and process equipment (heat exchangers, tanks, process vessels, valves) are used in the chemical and petrochemical industries primarily for corrosion resistance. Specific alloys are used in oil and gas downhole applications and nickel hydrometallurgy for their high strength (e. g.: titanium beta C alloy), corrosion resistance, or both. The pulp and paper industry uses titanium in process equipment exposed to corrosive media, such as sodium hypochlorite or wet chlorine gas (in the bleachery). Titanium is also used in sputtering targets. Powdered titanium acts as a non-evaporative getter, and is one of several gas-reactive materials used to remove gases from ultra-high vacuum systems. This application manifested in titanium sublimation pumps first employed in 1961, though the metal was first used in vacuum systems to prevent chambers from oxidizing in a design created by Raymond Herb in 1953. Titanium tetrachloride (TiCl4), a colorless liquid, is important as an intermediate in the process of making TiO2 and is also used to produce the Ziegler–Natta catalyst. Titanium tetrachloride is also used to iridize glass and, because it fumes strongly in moist air, it is used to make smoke screens. Consumer and architectural loudspeaker driver with a membrane with 25 mm diameter made from titanium; from a JBL TI 5000 loudspeaker box, Titanium metal is used in automotive applications, particularly in automobile and motorcycle racing where low weight and high strength and rigidity are critical. The metal is generally too expensive for the general consumer market, though some late model Corvettes have been manufactured with titanium exhausts. Titanium is used in many sporting goods: tennis rackets, golf clubs, lacrosse stick shafts; cricket, hockey, lacrosse, and football helmet grills, and bicycle frames and components. Although not a mainstream material for bicycle production, titanium bikes have been used by racing teams and adventure cyclists. Titanium is used in spectable frames, as it is durable and protect the lenses, though it may be less flexible than alternatives. Its biocompatibility is a potential benefit over other glasses frame materials. Titanium is a common material for backpacking cookware and eating utensils. Titanium horseshoes are preferred to steel by farriers because they are lighter and more durable. Some upmarket lightweight and corrosion-resistant tools, such as shovels, knife handles and flashlights, are made of titanium or titanium alloys. 's Guggenheim Museum, Bilbao Titanium has occasionally been used in architecture. The Monument to Yuri Gagarin, the first man to travel in space, as well as the upper part of the Monument to the Conquerors of Space on top of the Cosmonaut Museum in Moscow are made of titanium. The Guggenheim Museum Bilbao and the Cerritos Millennium Library were the first buildings in Europe and North America, respectively, to be sheathed in titanium panels. Titanium sheathing was used in the Frederic C. Hamilton Building in Denver, Colorado. Because of titanium's superior strength and light weight relative to other metals (steel, stainless steel, and aluminium), and because of advances in metalworking techniques, its use has become widespread in the manufacture of firearms. Primary uses include pistol frames and revolver cylinders. For the same reasons, it is used in the body of some laptop computers (for example, in Apple's PowerBook G4) Jewelry Because of its durability, titanium is used in some designer jewelry, such as titanium rings. Titanium's durability, light weight, and dent and corrosion resistance make it useful for watch cases. Titanium may be anodized to vary the thickness of the surface oxide layer, causing optical interference fringes and a variety of bright colors. With its variable coloration and chemical inertness, titanium is a popular metal for body piercing. Titanium has a minor use in dedicated non-circulating coins and medals. In 1999, the world's first titanium coin was minted for Gibraltar's millennium celebration. Pobjoy Mint, the British mint that produced the coin, continued to manufacture anodized titanium coins until its closure in 2023. The Gold Coast Titans, an Australian rugby league team, award a medal of pure titanium to their player of the year. Medical Because titanium is biocompatible (non-toxic and not rejected by the body), it has many medical uses, including surgical implements and implants, such as hip balls and sockets (joint replacement) and dental implants. Titanium and titanium alloy implants have been used in surgery since the 1950s, and are favored due to their low rate of corrosion, long life, and low Young's modulus. A titanium alloy that contains 6% aluminium and 4% vanadium commonly used in the aerospace industry is also a common material for artificial joints. Titanium has the inherent ability to osseointegrate, enabling use in dental implants that can last for over 30 years. This property is also useful for orthopedic implant applications. Biomedical implants coated with a combination of silver and titanium have been researched as a potential option for load-bearing implants that need antimicrobial surfaces. Complex implant scaffold designs can be 3D-printed using titanium alloys, which allows for more patient-specific applications and increased implant osseointegration. Because titanium is non-ferromagnetic, patients with titanium implants can be safely examined with magnetic resonance imaging (convenient for long-term implants). Preparing titanium for implantation in the body involves subjecting it to a high-temperature plasma arc which removes the surface atoms, exposing fresh titanium that is instantly oxidized. Titanium dioxide nanoparticles are widely used in electronics and the delivery of pharmaceuticals and cosmetics. Anticancer therapy studies Following the success of platinum-based chemotherapy, titanium(IV) complexes were among the first non-platinum compounds to be tested and accepted for clinical trials in cancer treatment. The advantage of titanium compounds lies in their high efficacy and low toxicity in vivo. In biological environments, hydrolysis leads to the safe and inert titanium dioxide. Despite these advantages, the first candidate compounds failed clinical trials due to insufficient efficacy to toxicity ratios and formulation complications. Further development resulted in the creation of potentially effective, selective, and stable titanium-based drugs. Nuclear waste storage Because of its corrosion resistance, containers made of titanium have been studied for the long-term storage of nuclear waste. Containers lasting more than 100,000 years are thought possible with manufacturing conditions that minimize material defects. A titanium "drip shield" has been considered for installation over containers of other types to enhance their longevity. ==Hazards and safety==

}} Titanium is non-toxic, even in large doses, and does not play any natural role inside the human body. As a powder or in the form of metal shavings, titanium metal poses a significant fire hazard and, when heated in air, an explosion hazard. Water and carbon dioxide are ineffective for extinguishing a titanium fire; Class D dry powder agents must be used instead. Titanium can also catch fire when a fresh, non-oxidized surface comes in contact with liquid oxygen. ==Function in plants==

contain up to 80 parts per million of titanium. An unknown mechanism in plants may use titanium to stimulate the production of carbohydrates and encourage growth. This may explain why most plants contain about 1 part per million (ppm) of titanium, food plants have about 2 ppm, and horsetail and nettle contain up to 80 ppm. ==See also==