Titanium

Characteristics

Titanium is a metal prized for its combination of strength and lightness. It is strong, has a low density, and remains quite ductile, especially when oxygen is absent. Its color is lustrous metallic-white, and it melts at a high 1,668 degrees Celsius, though it is not technically a refractory metal. It is paramagnetic and conducts both electricity and heat poorly compared to other metals, but it becomes a superconductor below 0.49 Kelvin.

Commercially pure titanium, at 99.2% purity, offers an ultimate tensile strength around 434 megapascals, matching common low-grade steel alloys but with less density. It is 60% denser than aluminum yet more than twice as strong as the typical 6061-T6 aluminum alloy. Some alloys, like Beta C, can reach tensile strengths above 1,400 megapascals, but the metal weakens when heated past 430 degrees Celsius. Titanium is not as hard as certain heat-treated steels, is non-magnetic, and is a poor heat and electricity conductor.

Machining it requires sharp tools and proper cooling to avoid galling. It has two allotropic forms: a hexagonal close-packed alpha structure that shifts to a body-centered cubic beta form at 882 degrees Celsius. When exposed to air, titanium instantly forms a thin, non-porous oxide passivation layer, initially just 1 to 2 nanometers thick, which slowly grows to about 25 nanometers over four years. This layer grants excellent corrosion resistance against oxidizing acids, but the metal dissolves in dilute hydrofluoric acid, hot hydrochloric acid, and hot sulfuric acid.

Compounds

The +4 oxidation state dominates titanium chemistry, though +3 compounds are also numerous. Titanium(IV) compounds often exhibit octahedral coordination geometry, with tetrahedral TiCl4 as a notable exception. The most important oxide is titanium dioxide (TiO2), which exists in three polymorphs: anatase, brookite, and rutile; all are white diamagnetic solids, though mineral samples may appear dark. These compounds adopt polymeric structures with titanium surrounded by six oxide ligands.

Titanates, such as barium titanate (BaTiO3), have a perovskite structure and exhibit piezoelectric properties, used in transducers for sound and electricity conversion. Star sapphires and rubies owe their asterism to titanium dioxide impurities. Reduced oxides of titanium include Ti3O5, a purple semiconductor used for vapor-coating surfaces; Ti2O3 with a corundum structure; and TiO with a rock salt structure, often nonstoichiometric. Titanium(IV) alkoxides, prepared from TiCl4 and alcohols, are colorless compounds that convert to TiO2 upon reaction with water and are used in sol-gel processes.

Titanium isopropoxide is employed in the Sharpless epoxidation to synthesize chiral organic compounds. Among titanium sulfides, only TiS2 has attracted significant interest; it has a layered structure and was used as a cathode in lithium batteries. Because Ti(IV) is a hard cation, titanium sulfides tend to hydrolyze to the oxide, releasing hydrogen sulfide.

Production

Titanium production is divided into three categories: manufacture of porous titanium metal sponge, titanium oxide pigment, and titanium mineral concentrates used for sponge, pigment, ingots, and coatings. These concentrates come mainly from ilmenite, as well as 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 estimated that out of 320,000 metric tons of titanium sponge produced globally in 2024, 220,000 (69%) came from China, with Japan second at 55,000 metric tons (17%).

Japan was the largest exporter of titanium sponge in 2024 but produced no titanium minerals domestically. A 2021 report listed the leading sponge producers as China (52%), Japan (24%), Russia (16%), and Kazakhstan (7%). Russia remains the third-largest producer through VSMPO-AVISMA, despite international sanctions. Global pigment production capacity was estimated at 9,800,000 metric tons in 2024.

Several extraction processes exist: the Becher process produces synthetic rutile from ilmenite but is not used at scale; the chloride process treats rutile with chlorine and carbon at high heat to produce titanium tetrachloride, then oxidizes it to titanium dioxide; the sulfate process uses sulfuric acid to leach titanium from ilmenite, producing titanyl sulfate, which is then hydrated and heated to yield titanium dioxide.

Applications

Titanium is used as an alloying element in steel to reduce grain size and as a deoxidizer, and in stainless steel to lower carbon content. It is alloyed with aluminium, vanadium, copper, iron, manganese, molybdenum, and other metals. Titanium mill products—sheet, plate, bar, wire, forgings, and castings—are used in industrial, aerospace, recreational, and emerging markets. Powdered titanium serves as a bright-burning source in pyrotechnics.

Titanium dioxide (TiO2) accounts for 95% of the world's refined titanium; it is a widely used white pigment in paints, cement, gemstones, and paper, and is chemically inert, UV-resistant, and highly opaque. It is also used in sunscreens for UV reflection and absorption. Titanium alloys, valued for their high tensile strength-to-density ratio, corrosion resistance, fatigue resistance, and ability to withstand moderately high temperatures, are used in aircraft, armor plating, naval ships, spacecraft, and missiles.

About two-thirds of all titanium metal produced goes into aircraft frames and engines; the 6AL-4V alloy accounts for nearly 50% of alloys used in aircraft applications.

Did You Know?

• Titanium powder or shavings pose a significant fire and explosion hazard when heated in air; water and carbon dioxide are ineffective, and Class D dry powder agents must be used.
• An unknown mechanism in plants may use titanium to stimulate carbohydrate production and growth; horsetail and nettle can contain up to 80 ppm of titanium.