= Titanium =

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= Titanium =
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Introduction
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Titanium is a chemical element; it has symbol Ti and atomic number 22.
Found in nature only as an oxide, it can be reduced to produce a
lustrous transition metal with a silver color, low density, and high
strength that is resistant to corrosion in sea water, aqua regia, and
chlorine.

Titanium was discovered in Cornwall, Great Britain, by William Gregor
in 1791 and was named by Martin Heinrich Klaproth after the Titans of
Greek mythology. The element occurs within a number of minerals,
principally rutile and ilmenite, which are widely distributed in the
Earth's crust and lithosphere; it is found in almost all living
things, as well as bodies of water, rocks, and soils. The metal is
extracted from its principal mineral ores by the Kroll and Hunter
processes. The most common compound, titanium dioxide (TiO2), is a
popular photocatalyst and is used in the manufacture of white
pigments. Other compounds include titanium tetrachloride (TiCl4), a
component of smoke screens and catalysts; and titanium trichloride
(TiCl3), which is used as a catalyst in the production of
polypropylene.

Titanium can be alloyed with iron, aluminium, vanadium, and
molybdenum, among other elements. The resulting titanium alloys are
strong, lightweight, and versatile, with applications including
aerospace (jet engines, missiles, and spacecraft), military,
industrial processes (chemicals and petrochemicals, desalination
plants, pulp, and paper), automotive, agriculture (farming), sporting
goods, jewelry, and consumer electronics. Titanium is also considered
one of the most biocompatible metals, leading to a range of medical
applications including prostheses, orthopedic implants, dental
implants, and surgical instruments.

The two most useful properties of the metal are its corrosion
resistance and strength-to-density ratio, the highest of any metallic
element. In its unalloyed condition, titanium is as strong as some
steels, but less dense. There are two allotropic forms and five
naturally occurring isotopes of this element, (46)Ti through (50)Ti,
with (48)Ti being the most abundant (73.8%).

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. Titanium
is superconducting when cooled below its critical temperature of 0.49
K.

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 as the most
commonly used 6061-T6 aluminium alloy. Certain titanium alloys (e.g.,
Beta C) achieve tensile strengths of over 1,400 MPa (200,000 psi).
However, titanium loses strength when heated above 430 °C.

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 metal is a dimorphic allotrope of a hexagonal close packed α form
that changes into a body-centered cubic (lattice) β form at 882 °C.
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.

Chemical properties
=====================
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. When it first forms, this protective layer is
only 1-2 nm thick but it continues to grow slowly, reaching a
thickness of 25 nm in four years. This layer gives titanium excellent
resistance to corrosion against oxidizing acids, but it will dissolve
in dilute hydrofluoric acid, hot hydrochloric acid, and hot sulfuric
acid.

Titanium is capable of withstanding attack by dilute sulfuric and
hydrochloric acids at room temperature, chloride solutions, and most
organic acids. However, titanium is corroded by concentrated 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. At room temperature, titanium is fairly inert to halogens, but
will violently combine with chlorine and bromine at 550 °C to form
titanium tetrachloride and titanium tetrabromide, respectively.

Titanium readily reacts with oxygen at 1200 °C in air, and at 610 °C
in pure oxygen, forming titanium dioxide. This oxide is also formed by
reaction between titanium and pure oxygen at room temperature and
pressure of . Titanium is one of the few elements that burns in pure
nitrogen gas, reacting at 800 °C to form titanium nitride, which
causes embrittlement.

Occurrence
============
Titanium is the ninth-most abundant element in Earth's crust (0.63% by
mass) and the seventh-most abundant metal. It is present as oxides in
most igneous rocks, in sediments derived from them, in living things,
and natural bodies of water. 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%.

Common titanium-containing minerals are anatase, brookite, ilmenite,
perovskite, rutile, and titanite (sphene). 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. Significant
titanium-bearing ilmenite deposits exist in Australia, Canada, China,
India, Mozambique, New Zealand, Norway, Sierra Leone, South Africa,
and Ukraine. Total reserves of anatase, ilmenite, and rutile are
estimated to exceed 2 billion tonnes.

The concentration of titanium is about 4 picomolar in the ocean. At
100 °C, the concentration of titanium in water is estimated to be less
than 10(−7) M at pH 7. The identity of titanium species in aqueous
solution remains unknown because of its low solubility and the lack of
sensitive spectroscopic methods, although only the 4+ oxidation state
is stable in air. No evidence exists for a biological role, although
rare organisms are known to accumulate high concentrations of
titanium.

Titanium is contained in meteorites, and it has been detected in the
Sun and in M-type stars (the coolest type) with a surface temperature
of 3200 °C. Rocks brought back from the Moon during the Apollo 17
mission are composed of 12.1% TiO2. Native titanium is only found in
rocks that have been exposed to pressures between roughly 2.8 to
4.0gigapascal on Earth, but it has been identified in nanocrystals on
the Moon.

Isotopes
==========
Naturally occurring titanium is composed of five stable isotopes:
(46)Ti, (47)Ti, (48)Ti, (49)Ti, and (50)Ti, with (48)Ti being the most
abundant (73.8% natural abundance). Twenty-three radioisotopes have
been characterized, the most stable of which are (44)Ti with a
half-life of 63 years; (45)Ti, 184.8 minutes; (51)Ti, 5.76 minutes;
and (52)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 (39)Ti to (66)Ti. The primary
decay mode for isotopes lighter than (46)Ti is positron emission (with
the exception of (44)Ti which undergoes electron capture), leading to
isotopes of scandium, and the primary mode for isotopes heavier than
(50)Ti is beta emission, leading to isotopes of vanadium. Titanium
becomes radioactive upon bombardment with deuterons, emitting mainly
positrons and hard gamma rays.

Compounds
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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.

Oxides, sulfides, and alkoxides
=================================
The most important oxide is TiO2, which exists in three important
polymorphs; anatase, brookite, and rutile. All three are white
diamagnetic solids, although mineral samples can appear dark, as in
rutile. They adopt polymeric structures in which Ti is surrounded by
six oxide ligands that link to other Ti centers.

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. Many
minerals are titanates, such as ilmenite (FeTiO3). Star sapphires and
rubies get their asterism (star-forming shine) from the presence of
titanium dioxide impurities.

A variety of reduced oxides (suboxides) of titanium are known, mainly
reduced stoichiometries of titanium dioxide obtained by atmospheric
plasma spraying. Ti3O5, described as a Ti(IV)-Ti(III) species, is a
purple semiconductor produced by reduction of TiO2 with hydrogen at
high temperatures, 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
======================================================================
Titanium was discovered in 1791 by the clergyman and geologist William
Gregor as an inclusion of a mineral in Cornwall, Great Britain. Gregor
recognized the presence of a new element in ilmenite when he found
black sand by a stream and noticed the sand was attracted by a magnet.
Analyzing the sand, he determined the presence of two metal oxides:
iron oxide (explaining the attraction to the magnet) and 45.25% of a
white metallic oxide he could not identify. 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 oxide was
independently rediscovered in 1795 by Prussian chemist Martin Heinrich
Klaproth in rutile from Boinik (the German name of Bajmócska), a
village in Hungary (now Bojničky in Slovakia).
Klaproth found that it contained a new element and named it for the
Titans of Greek mythology. After hearing about Gregor's earlier
discovery, he obtained a sample of manaccanite and confirmed that it
contained titanium.

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. An extraction of 95% pure
titanium was achieved by Lars Fredrik Nilson and Otto Petterson. To
achieve this they chlorinated titanium oxide in a carbon monoxide
atmosphere with chlorine gas before reducing it to titanium metal by
the use of sodium. Pure metallic titanium (99.9%) was first prepared
in 1910 by Matthew A. Hunter at Rensselaer Polytechnic Institute by
heating TiCl4 with sodium at 700-800 °C under great pressure in a
batch process known as the Hunter process. Titanium metal was not used
outside the laboratory until 1932 when William Justin Kroll produced
it by reducing titanium tetrachloride (TiCl4) with calcium. Eight
years later he refined this process with magnesium and with sodium in
what became known as the Kroll process. Although research continues to
seek cheaper and more efficient routes, such as the FFC Cambridge
process, the Kroll process is still predominantly used for commercial
production.

Titanium of very high purity was made in small quantities when Anton
Eduard van Arkel and Jan Hendrik de Boer discovered the iodide process
in 1925, by reacting with iodine and decomposing the formed vapors
over a hot filament to pure metal.

In the 1950s and 1960s, the Soviet Union pioneered the use of titanium
in military and submarine applications (Alfa class and Mike class) 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
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2024 production of ilmenite and rutile
Country !! thousand tonnes !! % of total
|China 3,300 35.3
|Mozambique 1,908 20.4
|South Africa 1,400 15.0
|Australia 600 6.4
|Norway 360 3.8
|Canada 350 3.7
|Senegal 300 3.2
|Madagascar 240 2.6
|India 222 4.3
|Ukraine 130 1.4
|United States 100 1.1
|Sierra Leone 60 0.6
|Kenya 40 0.4
|Other countries 350 3.7
|**World**||**9,360**||**100**
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. A prior report in
2021 noted that the four leading producers of titanium sponge were
China (52%), Japan (24%), Russia (16%) and Kazakhstan (7%). Russia
remains the third-largest producer of titanium sponge through the
efforts of the metallurgy company VSMPO-AVISMA, despite international
sanctions during the Russian invasion of Ukraine. Production
statistics on titanium dioxide pigment are not as clear-cut, but
estimates placed the maximum capacity on global pigment production at
in 2024.

Various methods have been developed to extract and refine titanium
from ore since the metal was first purified in 1910.

Mineral beneficiation processes
=================================
Several processes have been developed to extract titanium and usable
titanium-containing minerals from ore. The Becher process is an
industrial process used to produce synthetic rutile, a form of
titanium dioxide, from the ore ilmenite by removing iron. It is not
used at scale. The chloride process produces titanium tetrachloride
through treatment of rutile ore with chlorine and carbon at high heat,
then oxidizes the product with an oxygen flame or plasma to produce
titanium dioxide. 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.

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, titanium metal is obtained by reduction of titanium
tetrachloride (TiCl4) with magnesium metal in the Kroll process. The
complexity of this batch production in the Kroll process explains the
relatively high market value of titanium, despite the Kroll process
being less expensive than the Hunter process. To produce the TiCl4
required by the Kroll process, the dioxide is subjected to
carbothermic reduction in the presence of chlorine. In this process,
the chlorine gas is passed over a red-hot mixture of rutile or
ilmenite in the presence of carbon. After extensive purification by
fractional distillation, the TiCl4 is reduced with 800 C molten
magnesium in an argon atmosphere.
:2FeTiO3 + 7Cl2 + 6C ->[900^oC] 2FeCl3 + 2TiCl4 + 6CO
:TiCl4 + 2Mg ->[1100^oC] Ti + 2MgCl2

Arkel-Boer process
====================
The van Arkel-de Boer process was the first semi-industrial process
developed to produce pure titanium, invented by Anton Eduard van Arkel
and Jan Hendrik de Boer in 1925 for the electronics company Philips.
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, and a similar process
using further refined iodide was used to refine chromium. A desire to
develop processes that could be run continuously led to the
development of commercial processes to refine titanium.

Armstrong process
===================
Titanium powder is manufactured using a flow production process known
as the Armstrong process 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, and have
been researched and tested at laboratory and small pilot plant scales.
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.

One method that has been developed to potentially supplant the Kroll
process is known as hydrogen-assisted magnesiothermic reduction and
makes use of magnesium, hydrochloric acid, and a hydrogen atmosphere
to directly reduce titanium dioxide to pure titanium. The reduction of
titanium dioxide powder by magnesium in an atomphere of hydrogen can
be followed by a leaching step with hydrochloric acid, which removes
magnesium and residual non-titanium oxides. This is followed by
additional reduction and leaching steps, and eventually results in
pure titanium powder or titanium hydride.

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). Contamination causes a variety of
conditions, such as embrittlement, which reduce the integrity of the
assembly welds and lead to joint failure.

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.

Titanium alloys
=================
Common titanium alloys are made by reduction. For example,
cuprotitanium (rutile with copper added), ferrocarbon titanium
(ilmenite reduced with coke in an electric furnace), and
manganotitanium (rutile with manganese or manganese oxides) are
reduced.

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%).
The remaining grades are alloys, each designed for specific properties
of ductility, strength, hardness, electrical resistivity, creep
resistance, specific corrosion resistance, and combinations thereof.

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 is often alloyed with aluminium (to
refine grain size), vanadium, copper (to harden), iron, manganese,
molybdenum, and other metals. 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
===================================
Titanium dioxide () is the most common compound of the element, being
the end point of 95% of the world's refined titanium. It is a widely
used white pigment. 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. In
nature, this compound is found in the minerals anatase, brookite, and
rutile. Paint made with titanium dioxide does well in severe
temperatures and marine environments. Pure titanium dioxide has a very
high index of refraction and an optical dispersion higher than
diamond. Titanium dioxide is used in sunscreens because it reflects
and absorbs UV light.

Aerospace and marine
======================
Because titanium alloys have high tensile strength to density ratio,
high corrosion resistance, fatigue resistance, high crack resistance,
and ability to withstand moderately high temperatures without
creeping, they are used in aircraft, armor plating, naval ships,
spacecraft, and missiles. For these applications, titanium is alloyed
with aluminium, zirconium, nickel, vanadium, and other elements to
manufacture a variety of components including critical structural
parts, landing gear, firewalls, exhaust ducts (helicopters), and
hydraulic systems. About two thirds of all titanium metal produced is
used in aircraft frames and engines. The titanium 6AL-4V alloy
accounts for almost 50% of all alloys used in aircraft applications.

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, heater-chillers for salt water aquariums, fishing line and
leader, and divers' knives. Titanium is used in the housings and
components of ocean-deployed surveillance and monitoring devices for
science and military. The former Soviet Union developed techniques for
making submarines with hulls of titanium alloys, 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. In many industrial applications, titanium and
its alloys can serve as a potential substitute for other metals, such
as nickel, niobium, scandium, silver, tantalum, and tungsten.

Consumer and architectural
============================
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.

Titanium has occasionally been used in architecture. The 42.5 m
Monument to Yuri Gagarin, the first man to travel in space, as well as
the upper part of the 110 m 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) and
phones (such as the iPhone 15 Pro).

Jewelry
=========
Because of its durability, titanium is used in some designer jewelry,
such as titanium rings. Its inertness makes it hypoallergenic and
wearable in environments such as swimming pools. Titanium is also
alloyed with gold to produce an alloy that can be marketed as 24-karat
gold, because the 1% of alloyed Ti is insufficient to require a lesser
mark. The resulting alloy is roughly the hardness of 14-karat gold and
is more durable than pure 24-karat gold.

Titanium's durability, light weight, and dent and corrosion resistance
make it useful for watch cases. Some artists work with titanium to
produce sculptures, decorative objects and furniture. 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. These benefit from
titanium's lower modulus of elasticity to more closely match that of
the bone that such devices are intended to repair. As a result,
skeletal loads are more evenly shared between bone and implant,
leading to a lower incidence of bone degradation due to stress
shielding and periprosthetic bone fractures, which occur at the
boundaries of orthopedic implants. However, titanium alloys' stiffness
is still more than twice that of bone, so adjacent bone bears a
greatly reduced load and may deteriorate. 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.

Modern advancements in additive manufacturing techniques have
increased potential for titanium use in orthopedic implant
applications. 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 is used for the surgical instruments used in image-guided
surgery, as well as wheelchairs, crutches, and any other products
where high strength and low weight are desirable.

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
======================================================================
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Titanium is non-toxic, even in large doses, and does not play any
natural role inside the human body. An estimated 0.8milligrams of
titanium is ingested by humans each day, but most passes through the
digestive system without being absorbed in the tissues. However, it
can sometimes bioaccumulate in tissues that contain silica. Yellow
nail syndrome has been reported in individuals that have been exposed
to titanium, though the disorder's rarity have made it difficult to
determine a direct association between exposure and disorder
development.

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. When used in the
production or handling of chlorine, titanium exposed to dry chlorine
gas may result in a titanium-chlorine fire. Titanium can also catch
fire when a fresh, non-oxidized surface comes in contact with liquid
oxygen.

Function in plants
======================================================================
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
======================================================================
* Titanium alloys
* Suboxide
* Titanium in zircon geothermometry
* Titanium Man

External links
======================================================================
* [https://books.google.com/books?id=7iwDAAAAMBAJ&pg=RA2-PA46
"Titanium: Our Next Major Metal"] in 'Popular Science' (October 1950),
one of first general public detailed articles on Titanium
* [http://www.periodicvideos.com/videos/022.htm Titanium] at 'Periodic
Videos' (University of Nottingham)
* [https://titanium.org/ Titanium.org]: official website of the
International Titanium Association, an industry association
*
[https://www.phase-trans.msm.cam.ac.uk/2003/titanium.movies/titanium.html
Metallurgy of Titanium and its Alloys] - slide presentations, movies,
and other material from Harshad Bhadeshia and other Cambridge
University metallurgists

License
=========
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Original Article: http://en.wikipedia.org/wiki/Titanium