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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, 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 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 oxidize 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 is a very reactive metal that burns in normal air at lower
temperatures than the melting point. Melting is possible only in an
inert atmosphere or vacuum. At 550 °C, it combines with chlorine. It
also reacts with the other halogens and absorbs hydrogen.
Titanium readily reacts with oxygen at 1200 °C in air, and at 610 °C
in pure oxygen, forming titanium dioxide. Titanium is one of the few
elements that burns in pure nitrogen gas, reacting at 800 °C to form
titanium nitride, which causes embrittlement. Because of its high
reactivity with oxygen, nitrogen, and many other gases, titanium that
is evaporated from filaments is the basis for titanium sublimation
pumps, in which titanium serves as a scavenger for these gases by
chemically binding to them. Such pumps inexpensively produce extremely
low pressures in ultra-high vacuum systems.
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. About 210,000 tonnes of titanium metal sponge were
produced in 2020, mostly in China (110,000 t), Japan (50,000 t),
Russia (33,000 t) and Kazakhstan (15,000 t). Total reserves of
anatase, ilmenite, and rutile are estimated to exceed 2 billion
tonnes.
2017 production of titanium minerals and slag
Country !! thousand tonnes !! % of total
|China 3,830 33.1
|Australia 1,513 13.1
|Mozambique 1,070 9.3
|Canada 1,030 8.9
|South Africa 743 6.4
|Kenya 562 4.9
|India 510 4.4
|Senegal 502 4.3
|Ukraine 492 4.3
|**World**||**11,563**||**100**
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 (pure metallic) is
very rare.
Isotopes
==========
Naturally occurring titanium is composed of five stable isotopes:
46Ti, 47Ti, 48Ti, 49Ti, and 50Ti, with 48Ti being the most abundant
(73.8% natural abundance). At least 21 radioisotopes have been
characterized, the most stable of which are 44Ti with a half-life of
63 years; 45Ti, 184.8 minutes; 51Ti, 5.76 minutes; and 52Ti, 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 in atomic weight from (39Ti) to
(64Ti). The primary decay mode for isotopes lighter than 46Ti is
positron emission (with the exception of 44Ti which undergoes electron
capture), leading to isotopes of scandium, and the primary mode for
isotopes heavier than 50Ti 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.
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 (see
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.
Anticancer therapy studies
============================
Following the success of platinum-based chemotherapy, titanium(IV)
complexes were among the first non-platinum compounds to be tested for
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.
History
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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. As of 2021, the four leading producers of titanium sponge were
China (52%), Japan (24%), Russia (16%) and Kazakhstan (7%).
Mineral beneficiation processes
=================================
* The Becher process is an industrial process used to produce
synthetic rutile, a form of titanium dioxide, from the ore ilmenite.
* The Chloride process.
* The Sulfate process: "relies on sulfuric acid (H2SO4) to leach
titanium from ilmenite ore (FeTiO3). The resulting reaction produces
titanyl sulfate (TiOSO4). A secondary hydrolysis stage is used to
break the titanyl sulfate into hydrated TiO2 and H2SO4. Finally, heat
is used to remove the water and create the end product - pure TiO2."
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
for pure Titanium. It involves thermal decomposition of titanium
tetraiodide.
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) is filtered from the extra sodium. Titanium is
then separated from the salt by water washing. Both sodium and
chlorine are recycled to produce and process more titanium
tetrachloride.
Pilot plants
==============
Methods for electrolytic production of Ti metal from using molten
salt electrolytes have been researched and tested at laboratory and
small pilot plant scales. The lead author of an impartial review
published in 2017 considered his own process "ready for scaling up." A
2023 review "discusses the electrochemical principles involved in the
recovery of metals from aqueous solutions and fused salt
electrolytes", with particular attention paid to titanium. While some
metals such as nickel and copper can be refined by electrowinning at
room temperature, titanium must be in the molten state and "there is a
strong chance of attack of the refractory lining by molten titanium."
Zhang et al concluded their Perspective on Thermochemical and
Electrochemical Processes for Titanium Metal Production in 2017 that
"Even though there are strong interests in the industry for finding a
better method to produce Ti metal, and a large number of new concepts
and improvements have been investigated at the laboratory or even at
pilot plant scales, there is no new process to date that can replace
the Kroll process commercially."
The Hydrogen assisted magnesiothermic reduction (HAMR) process uses
titanium dihydride.
Fabrication
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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 is very complicated, and may include Friction
welding, cryo-forging, and Vacuum arc remelting.
Applications
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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
===================================
About 95% of all titanium ore is destined for refinement into titanium
dioxide (), an intensely white permanent pigment used in paints,
paper, toothpaste, and plastics. 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. In fact, about two thirds of all titanium metal
produced is used in aircraft engines and frames. 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). Other
applications include ultrasonic welding, wave soldering, and
sputtering targets.
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
============================
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, and a Corvette Z06's LT4
supercharged engine uses lightweight, solid titanium intake valves for
greater strength and resistance to heat.
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 alloys are used in spectacle frames that are rather expensive
but highly durable, long lasting, light weight, and cause no skin
allergies. Titanium is a common material for backpacking cookware and
eating utensils. Though more expensive than traditional steel or
aluminium alternatives, titanium products can be significantly lighter
without compromising strength. Titanium horseshoes are preferred to
steel by farriers because they are lighter and more durable.
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 110 m Monument to the Conquerors of Space on top of the
Cosmonaut Museum in Moscow are made of titanium for the metal's
attractive color and association with rocketry. 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
recent advances in metalworking techniques, its use has become more
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).
In 2023, Apple launched the iPhone 15 Pro, which uses a titanium
enclosure.
Some upmarket lightweight and corrosion-resistant tools, such as
shovels, knife handles and flashlights, are made of titanium or
titanium alloys.
Jewelry
=========
Because of its durability, titanium has become more popular for
designer jewelry (particularly, titanium rings). Its inertness makes
it a good choice for those with allergies or those who will be wearing
the jewelry 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 this 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, Gibraltar released the world's first titanium coin
for the millennium celebration. 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 that can stay in place for up to 20 years. The titanium is
often alloyed with about 4% aluminium or 6% Al and 4% vanadium.
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 (Young's modulus) 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.
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.
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.
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.
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" could also be installed over containers of other types
to enhance their longevity.
Precautions
======================================================================
Titanium is non-toxic even in large doses and does not play any
natural role inside the human body. An estimated quantity of 0.8
milligrams of titanium is ingested by humans each day, but most passes
through without being absorbed in the tissues. It does, however,
sometimes bio-accumulate in tissues that contain silica. One study
indicates a possible connection between titanium and yellow nail
syndrome.
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 should
not be exposed to dry chlorine gas because it may result in a
titanium-chlorine fire.
Titanium can 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
=========
All content on Gopherpedia comes from Wikipedia, and is licensed under CC-BY-SA
License URL:
http://creativecommons.org/licenses/by-sa/3.0/
Original Article:
http://en.wikipedia.org/wiki/Titanium
