Titanium
30040
226104858
2008-07-16T21:04:30Z
Diligent Terrier
2499413
Reverted edits by [[Special:Contributions/66.196.227.211|66.196.227.211]] to last version by Diligent Terrier (using [[WP:HG|Huggle]])
{{pp-move-vandalism|small=yes}}
{{Infobox titanium}}
'''Titanium''' ({{pronEng|taɪˈteɪniəm}}) is a [[chemical element]] with the symbol '''Ti''' and [[atomic number]] 22. It is a light, strong, lustrous, [[corrosion]]-resistant (including to [[sea water]] and [[chlorine]]) [[transition metal]] with a grayish [[color]]. Titanium can be [[alloy]]ed with [[iron]], [[aluminium]], [[vanadium]], [[molybdenum]], among other elements, to produce strong lightweight alloys for aerospace ([[jet engine]]s, [[missile]]s, and [[spacecraft]]), military, industrial process (chemicals and petro-chemicals, [[desalination plant]]s, pulp, and paper), automotive, agri-food, medical [[prostheses]], orthopaedic [[Implant (medicine)|implant]]s, dental endodontic instruments and files, [[dental implant]]s, sporting goods, jewelry, [[cell phone|mobile phones]], and other applications.<ref name="EBC">{{cite encyclopedia|encyclopedia=Encyclopædia Britannica Concise|title=Titanium| year=2007}}</ref> Titanium was discovered in [[England]] by [[William Gregor]] in 1791 and named by [[Martin Heinrich Klaproth]] for the [[Titan (mythology)|Titan]]s of [[Greek mythology]].
The element occurs within a number of mineral deposits, principally [[rutile]] and [[ilmenite]], which are widely distributed in the [[Earth]]'s crust and lithosphere, and it is found in almost all living things, rocks, water bodies, and soils.<ref name="EBC"/> The metal is extracted from its principal mineral ores via the [[Kroll process]]<ref name="LANL"/> or the [[Hunter process]]. Its most common compound, [[titanium dioxide]], is used in the manufacture of white pigments.<ref name="HistoryAndUse">{{cite book |last=Krebs |first=Robert E. |title=The History and Use of Our Earth's Chemical Elements: A Reference Guide (2nd edition) |publisher=Greenwood Press |location=[[Westport, CT]] |id=ISBN 0313334382 |year=2006}}</ref> Other compounds include [[titanium tetrachloride]] (TiCl<sub>4</sub>) (used in [[smoke screen]]s/[[skywriting]] and as a [[catalyst]]) and [[titanium trichloride]] (used as a catalyst in the production of [[polypropylene]]).<ref name="EBC"/>
The two most useful properties of the metal form are corrosion resistance, and the highest strength-to-weight ratio of any metal.<ref>{{cite book |title=TITANIUM: A Technical Guide |year=1988 |author=Matthew J. Donachie, Jr. |publisher=ASM International |location=Metals Park, OH|pages=p.11 |id=ISBN 0871703092}}</ref> In its unalloyed condition, titanium is as strong as some [[steel]]s, but 45% lighter.<ref name="EncyChem"/><!-- page 738 --> There are two [[allotropy|allotropic]] forms<ref name="TICE6th">{{cite encyclopedia|title=Titanium|encyclopedia=[[Columbia Encyclopedia]]|edition=6th edition|year=2000 – 2006|publisher=[[Columbia University Press]]|url=http://www.answers.com/Titanium|location=New York|id=ISBN 0787650153}}</ref> and five naturally occurring [[isotope]]s of this element; <sup>46</sup>Ti through <sup>50</sup>Ti with <sup>48</sup>Ti being the most [[natural abundance|abundant]] (73.8%).<ref name="EnvChem">{{cite web |url=http://environmentalchemistry.com/yogi/periodic/Ti-pg2.html#Nuclides |title=Periodic Table of Elements: Ti - Titanium |accessdate=2006-12-26 |author=Barbalace, Kenneth L. |date=2006}}</ref> Titanium's properties are chemically and physically similar to [[zirconium]].
== History ==
Titanium was [[discovery of the chemical elements|discovered]] [[Inclusion (mineral)|included]] in a [[mineral]] in [[Cornwall]], [[England]], in 1791 by amateur geologist and pastor [[William Gregor]], the then vicar of [[Creed, Cornwall|Creed]] parish. He recognized the presence of a new element in [[ilmenite]]<ref name="HistoryAndUse"/> when he found black sand by a stream in the nearby [[parish]] of [[Manaccan]] and noticed the sand was attracted by a [[magnet]]. Analysis of the sand 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.<ref name="EncyChem">{{cite book |title=''The Encyclopedia of the Chemical Elements'' |year=1968 |author=Barksdale, Jelks |publisher=[[Reinhold Book Corporation]] |location=[[Skokie, Illinois]] |pages=732-38 "Titanium"|id=LCCCN 68-29938}}</ref><!--page 732--> Gregor, realizing that the unidentified oxide contained a metal that did not match the properties of any known element, reported his findings to the [[Royal Geological Society of Cornwall]] and in the German science journal ''[[Crell's Annalen]]''.<ref name="BuildingBlocks451-3">{{cite book |last=Emsley |first=John |title=Nature's Building Blocks: An A-Z Guide to the Elements |year=2001 |id=ISBN 0-19-850341-5 |pages=pp. 451 – 53 |publisher=[[Oxford University Press]] |location=Oxford}}</ref>
[[Image:Martin Heinrich Klaproth.jpg|thumb|left|<small>[[Martin Heinrich Klaproth]] named titanium for the [[titan (mythology)|Titans]] of [[Greek mythology]].</small>]]
Around the same time, [[Franz Joseph Muller]] also produced a similar substance, but could not identify it.<ref name="HistoryAndUse"/> The oxide was independently rediscovered in 1795 by [[Germany|German]] chemist [[Martin Heinrich Klaproth]] in [[rutile]] from [[Hungary]].<ref>[http://homepage.mac.com/dtrapp/Elements/myth.html Origins of the Element Names: Names Derived from Mythology or Superstition]</ref> Klaproth found that it contained a new element and named it for the [[titan (mythology)|Titans]] of [[Greek mythology]].<ref name="BuildingBlocks451-3"/> After hearing about Gregor's earlier discovery, he obtained a sample of ''manaccanite'' and confirmed it contained titanium.
The processes required to extract titanium from its various ores are laborious and costly; it is not possible to reduce in the normal manner, by heating in the presence of [[carbon]], because that produces [[titanium carbide]].<ref name="BuildingBlocks451-3"/> Pure metallic titanium (99.9%) was first prepared in 1910 by [[Matthew A. Hunter]] by heating Ti[[chlorine|Cl]]<sub>4</sub> with [[sodium]] in a [[steel bomb]] at 700–800 °C in the [[Hunter process]].<ref name="LANL"/> Titanium metal was not used outside the laboratory until 1946 when [[William Justin Kroll]] proved that it could be commercially produced by reducing [[titanium tetrachloride]] with [[magnesium]] in what came to be known as the [[Kroll process]]. Although research continues into more efficient and cheaper processes (e.g., [[FFC Cambridge]]), the Kroll process is still used for commercial production.<ref name="HistoryAndUse"/><ref name="LANL"/>
[[Image:Titanium crystal bar.jpg|thumb|left|A titanium crystal bar made by the [[Crystal bar process|iodide process]]]]
Titanium of very high purity was made in small quantities when [[Anton Eduard van Arkel]] and [[Jan Hendrik de Boer]] discovered the iodide, or [[Crystal bar process|crystal bar]], process in 1925, by reacting with iodine and decomposing the formed vapors over a hot filament to pure metal.<ref>{{cite journal |last=van Arkel |first=A. E. |authorlink=Anton Eduard van Arkel |coauthors=de Boer, J. H. |title=Preparation of pure titanium, zirconium, hafnium, and thorium metal |journal=[[Zeitschrift für Anorganische und Allgemeine Chemie|Z. Anorg. Allg. Chem.]] |year=1925 |volume=148 |pages=345 – 50}}</ref>
In the 1950s and 1960s the [[Soviet Union]] pioneered the use of titanium in military and submarine applications ([[Alfa class submarine|Alfa Class]] and [[Soviet submarine K-278 Komsomolets|Mike Class]])<ref>{{cite web |url=http://warfare.ru/?lang=&linkid=1756&catid=243 |title=Submarines: general information | first=Eugene |last=Yanko |coauthors=Omsk VTTV Arms Exhibition and Military Parade JSC |date=2006 |accessdate=2006-12-26}}</ref> as part of programs related to the Cold War.<ref>{{cite news
| last =Stainless Steel World
| title =VSMPO Stronger Than Ever
| pages =16–19
| publisher =KCI Publishing B.V.
| date =July/August 2001
| url =http://www.stainless-steel-world.net/pdf/ssw0107.pdf?issueID=30
| accessdate =2007-01-02 }}
</ref>
Starting in the early 1950s, Titanium began to be used extensively for military aviation purposes, particularly in high-performance jets, starting with aircraft such as the [[F-100 Super Sabre|F100 Super Sabre]] and [[Lockheed A-12]].
In the USA, the [[United States Department of Defense|Department of Defense]] realized the strategic importance of the metal<ref>{{cite book |title=Titanium: Past, Present, and Future |publisher=national Academy Press |pages=R9 |author=NATIONAL MATERIALS ADVISORY BOARD, Commission on Engineering and Technical Systems (CETS), National Research Council | id=NMAB-392 |location=Washington, DC|url= http://books.nap.edu/openbook.php?record_id=1712&page=R1|year=1983}}</ref> and supported early efforts of commercialization.<ref>{{cite web
| title =Titanium Metals Corporation. Answers.com. Encyclopedia of Company Histories,
| publisher =Answers Corporation
| date =2006
| url =http://www.answers.com/topic/titanium-metals-corporation
| accessdate = 2007-01-02 }}</ref>
<!-- NEEDS CITE: During this period, the U.S. obtained a large share of its refined Titanium clandestinely from the Soviet Union through front companies set up in Europe. Indeed, titanium for the highly successful U.S. [[SR-71]] [[reconnaissance aircraft]] was acquired from the Soviet Union at the height of the Cold War. /NEEDS CITE -->
Throughout the period of the [[Cold War]], titanium was considered a Strategic Material by the U.S. government, and a large stockpile of titanium sponge was maintained by the Defense National Stockpile Center, which was finally depleted in 2005.<ref>{{cite book |title=Strategic and Critical Materials Report to the Congress. Operations under the Strategic and Critical Materials Stock Piling Act during the Period October 2004 through September 2005 |publisher=[[United States Department of Defense]] |pages=§ 3304 |author=[[Defense National Stockpile Center]] |url=https://www.dnsc.dla.mil/..%5CUploads/Materials/admin_4-26-2006_14-19-33_SRC%202005%20Ops%20Report%20Complete.pdf |year=2006}}</ref> Today, the world's largest producer, Russian-based [[VSMPO-Avisma]], is estimated to account for about 29% of the world market share.<ref>{{cite news |date=[[2006-02-15]] |title=Boeing's Plan to Land Aeroflot |last=Bush |first=Jason |publisher=[[BusinessWeek]] |url=http://www.businessweek.com/technology/content/feb2006/tc20060215_694672.htm?campaign_id=search |accessdate=2006-12-29}}</ref>
In 2006, the U.S. Defense Agency awarded $5.7 million to a two-company consortium to develop a new process for making titanium metal [[powder metallurgy|powder]]. Under heat and pressure, the powder can be used to create strong, lightweight items ranging from armor plating to components for the aerospace, transportation, and chemical processing industries.<ref>{{cite web |url=http://www2.dupont.com/Government/en_US/news_events/article20060912.html |title=U.S. Defense Agency Awards $5.7 Million to DuPont and MER Corporation for New Titanium Metal Powder Process |author=[[DuPont]] |date=[[2006-12-09]] |accessdate=2006-12-26}}</ref>
== Characteristics ==
===Physical===
A [[metal]]lic [[chemical element|element]], titanium is recognized for its high strength-to-weight ratio.<ref name="TICE6th"/> It is a light, strong metal with low [[density]] that, when pure, is quite [[ductility|ductile]] (especially in an [[oxygen]]-free environment),<ref name="TIEB2005">{{cite encyclopedia|encyclopedia=Encyclopædia Britannica|title=Titanium| year=2006| url=http://www.britannica.com/eb/article-9072643/titanium| accessdate=2006-12-29}}</ref> lustrous, and metallic-white in [[color]]. The relatively high [[melting point]] (over 1,649 °C or 3,000 °F) makes it useful as a [[refractory metal]].
Commercial (99.2% pure) grades of titanium have ultimate [[tensile strength]] of about 63,000 [[Pound per square inch|psi]] (434 [[Megapascal|MPa]]), equal to that of some steel alloys, but are 45% lighter.<ref name="EncyChem"/><!-- page 738 --> Titanium is 60% heavier than [[aluminium]], but more than twice as strong<ref name="EncyChem"/><!-- page 738 --> as the most commonly used 6061-T6 aluminium alloy. Certain titanium alloys (e.g., Beta C) achieve tensile strengths of over 200,000 psi (1380 MPa).<ref>{{cite book |title=TITANIUM: A Technical Guide |year=1988 |author=Matthew J. Donachie, Jr. |publisher=ASM International |location=Metals Park, OH|pages=Appendix J, Table J.2 |id=ISBN 0871703092}}</ref>
However, titanium loses strength when heated above 430 °C (800 °F).<ref name="EncyChem"/><!-- page 734 -->
It is fairly hard (although not as hard as some grades of heat-treated steel), non-magnetic and a poor conductor of heat. Machining requires precautions, as the material will soften and [[wiktionary:gall|gall]] if sharp tools and proper cooling methods are not used. Like those made from steel, titanium structures have a [[fatigue limit]] which guarantees longevity in some applications.<ref name="BuildingBlocks455">{{cite book |last=Emsley |first=John |title=Nature's Building Blocks: An A-Z Guide to the Elements |year=2001 |id=ISBN 0-19-850341-5 |pages=455 |publisher=[[Oxford University Press]] |location=Oxford}}</ref>
The metal is a dimorphic [[allotropy|allotrope]] with the hexagonal alpha form changing into the body-centered cubic (lattice) beta form at 882 °C (1,619 °F).<ref name="EncyChem"/><!-- page 734 --> The [[specific heat capacity|specific heat]] of the alpha form increases dramatically as it is heated to this transition temperature but then falls and remains fairly constant for the beta form regardless of temperature.<ref name="EncyChem"/><!-- page 734 --> Similar to [[zirconium]] and [[hafnium]], an additional omega phase exists, which is thermodynamically stable at high pressures, but which may exist metastably at ambient pressures. This phase is usually [[hexagonal]] (''ideal'') or [[trigonal]] (''distorted'') and can be viewed as being due to a soft longitudinal acoustic [[phonon]] of the beta phase causing collapse of (111) planes of atoms.<ref>{{cite journal |last=Sikka |first=S. K. |authorlink=S. K. Sikka |coauthors=Vohra, Y. K., Chidambaram, R.|title=Omega phase in materials |journal=[[Progress in Materials Science]] |year=1982 |volume=27 |pages=245 – 310|doi=10.1016/0079-6425(82)90002-0}}</ref>
===Chemical===
The most noted chemical property of titanium is its excellent resistance to [[corrosion]]; it is almost as resistant as [[platinum]], capable of withstanding attack by [[acid]]s, moist [[chlorine]] gas, and by common [[salt]] solutions.<ref name="TICE6th"/> Pure titanium is not [[solubility|soluble]] in water but is soluble in concentrated acids.<ref>{{cite journal |title=Pitting Corrosion of Titanium |journal=[[Journal of the Electrochemical Society|J. Electrochem. Soc.]] | volume=141 |issue=3 |pages=636 – 42 |year=1994 |author=Casillas, N.; Charlebois, S.; Smyrl, W. H.; White, H. S.|
url=http://ecsdl.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=JESOAN000141000003000636000001&idtype=cvips&prog=normal |doi=10.1149/1.2054783}} [http://ecsdl.org/getabs/servlet/GetabsServlet?prog=normal&id=JESOAN000141000003000636000001&idtype=cvips&gifs=Yes ''Abstract'']</ref>
While the following [[pourbaix diagram]] shows that titanium is thermodynamically a very reactive metal, it is slow to react with water and air.
[[Image:Titanium in water porbiax diagram.png|thumb|right|240px|The [[Pourbaix diagram]] for titanium in pure water, perchloric acid or sodium hydroxide<ref name="medusa">Ignasi Puigdomenech, ''Hydra/Medusa Chemical Equilibrium Database and Plotting Software'' (2004) KTH Royal Institute of Technology, freely downloadable software at [http://www.kemi.kth.se/medusa/]</ref>]]
This metal forms a [[passivation|passive]] and protective [[oxide]] coating (leading to increased corrosion-resistance) when exposed to elevated temperatures in air, but at room temperatures it resists [[tarnish]]ing.<ref name="TIEB2005"/> When it first forms, this protective layer is only 1–2 [[nanometre|nm]] thick but continues to slowly grow; reaching a thickness of 25 nm in four years.<ref name="BuildingBlocks451-3"/>
Titanium burns when heated in air 610 °C (1,130 °F) or higher, forming titanium dioxide.<ref name="TICE6th"/> It is also one of the few elements that burns in pure [[nitrogen]] gas (it burns at 800 °C or 1,472 °F and forms [[titanium nitride]], which causes embrittlement).<ref name="TI_Encarta2005">{{cite encyclopedia |title=Titanium |encyclopedia=Microsoft Encarta |year=2005| url=http://encarta.msn.com/encyclopedia_761569280/Titanium.html |accessdate=2006-12-29}}</ref><!-- many sources incorrectly say this is the *only* element to burn in nitrogen, magnesium will also do so --> Titanium is resistant to dilute [[sulfuric acid|sulfuric]] and [[hydrochloric acid]], along with [[chlorine]] gas, [[chloride]] solutions, and most [[organic acid]]s.<ref name="LANL"/> It is [[paramagnetic]] (weakly attracted to [[magnet]]s) and has fairly low [[electrical conductivity|electrical]] and [[thermal conductivity]].<ref name="TIEB2005"/>
Experiments have shown that natural titanium becomes [[radioactive]] after it is bombarded with [[deuteron]]s, emitting mainly [[positron]]s and hard [[gamma ray]]s.<ref name="LANL"/> When it is red hot the metal combines with oxygen, and when it reaches 550 °C (1,022 °F) it combines with [[chlorine]].<ref name="LANL"/> It also reacts with the other [[halogen]]s and absorbs [[hydrogen]].<ref name="HistoryAndUse"/>
== Occurrence==
<div style="float:right; margin-left:0.5em; text-align:center;">
{| class="wikitable"
! Producer !! Thousands of tons !! % of total
|-
|[[Australia]]
|1291.0
|30.6
|-
|[[South Africa]]
|850.0
|20.1
|-
|[[Canada]]
|767.0
|18.2
|-
|[[Norway]]
|382.9
|9.1
|-
|[[Ukraine]]
|357.0
|8.5
|-
|''Other countries''
|''573.1''
|''13.6''
|-
|'''Total world'''
|'''4221.0'''
|'''100.1'''
|}
<small>Source: 2003 production of titanium dioxide.</small><ref>{{cite book |last=Cordellier |first=Serge |coauthors=Didiot, Béatrice |title=L'état du monde 2005: annuaire économique géopolitique mondial |location=Paris |publisher=La Découverte |year=2004}}</ref><br/><small>Due to rounding, values do not sum to 100%.</small></div>
Titanium is always bonded to other elements in nature. It is the ninth-most abundant element in the [[Earth]]'s crust (0.63% by [[mass]])<ref name="EncyChem"/><!-- page 732 --> and the seventh-most abundant metal. It is present in most [[igneous rock]]s and in [[sedimentary rock|sediments]] derived from them (as well as in living things and natural bodies of water).<ref name="TIEB2005"/><ref name="LANL">{{cite web|title=Titanium|url=http://periodic.lanl.gov/elements/22.html|date=2004|accessdate=2006-12-29| publisher=[[Los Alamos National Laboratory]]}}</ref> In fact, of the 801 types of igneous rocks analyzed by the [[United States Geological Survey]], 784 contained titanium.<ref name="EncyChem"/><!-- page 732 --> Its proportion in soils is approximately 0.5 to 1.5%.<ref name="EncyChem"/><!-- page 732 -->
It is widely distributed and occurs primarily in the [[mineral]]s [[anatase]], [[brookite]], [[ilmenite]], [[perovskite]], [[rutile]], [[titanite]] (sphene), as well in many [[iron]] ores. Of these minerals, only rutile and ilmenite have any economic importance, yet even they are difficult to find in high concentrations.<ref name="HistoryAndUse"/> Significant titanium-bearing ilmenite deposits exist in western [[Australia]], [[Canada]], [[China]], [[New Zealand]], [[Norway]],[[India]] and [[Ukraine]]. Large quantities of rutile are also mined in [[North America]] and [[South Africa]] and help contribute to the annual production of 90,000 [[tonne]]s of the metal and 4.3 million tonnes of titanium dioxide. Total known reserves of titanium are estimated to exceed 600 million tonnes.<ref name="BuildingBlocks451-3"/>
Titanium is contained in [[meteorite]]s and has been detected in the [[sun]] and in [[Stellar classification|M-type]] [[star]]s;<ref name="LANL"/> the coolest type of star with a surface temperature of 3,200 °C (5,792 °F).<ref name="BuildingBlocks451-3"/> [[Rock (geology)|Rock]]s brought back from the [[moon]] during the [[Apollo 17]] mission are composed of 12.1% TiO<sub>2</sub>.<ref name="LANL"/> It is also found in [[coal]] ash, [[plant]]s, and even the [[human]] body.<!--(while harmless, it is not believed to be an [[essential element]])-->
==Production and fabrication==
[[Image:TitaniumUSGOV.jpg|thumb|Titanium (Mineral Concentrate)]]
The processing of titanium metal occurs in 4 major steps:<ref>{{cite book |title=TITANIUM: A Technical Guide |year=1988 |author=Matthew J. Donachie, Jr. |publisher=ASM International |location=Metals Park, OH|pages=Chapter 4 |id=ISBN 0871703092}}</ref> 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 the metal reacts with oxygen at high temperatures it cannot be produced by [[reduction (chemistry)|reduction]] of its dioxide. Titanium metal is therefore produced commercially by the [[Kroll process]], a complex and expensive [[batch production|batch process]]. (The relatively high market value of titanium is mainly due to its processing, which sacrifices another expensive metal, magnesium.<ref name="EncyChem"/><!--page 733-->) In the Kroll process, the oxide is first converted to chloride through [[carbochlorination]], whereby [[chlorine]] gas is passed over red-hot [[rutile]] or [[ilmenite]] in the presence of [[carbon]] to make [[Titanium tetrachloride|TiCl<sub>4</sub>]]. This is condensed and purified by [[fractional distillation]] and then [[reduction (chemistry)|reduced]] with 800 °C molten [[magnesium]] in an [[argon]] atmosphere.<ref name="TICE6th"/>
A more recently developed method, the [[FFC Cambridge process]],<ref>{{cite journal |last=Chen |first=George Zheng |coauthors=Fray, Derek J.; Farthing, Tom W. |url=http://www.nature.com/nature/journal/v407/n6802/full/407361a0.html |title=Direct electrochemical reduction of titanium dioxide to titanium in molten calcium chloride |journal=[[Nature (journal)|Nature]] |year=2000 |volume=407 |pages=361 – 64 |doi=10.1038/35030069}} [http://www.nature.com/nature/journal/v407/n6802/abs/407361a0.html ''Abstract'']</ref> may eventually replace the Kroll process. This method uses [[titanium dioxide]] powder (which is a refined form of [[rutile]]) as feedstock to make the end product which is either a powder or sponge. If mixed oxide powders are used, the product is an alloy manufactured at a much lower cost than the conventional multi-step melting process. The FFC Cambridge process may render titanium a less rare and expensive material for the [[aerospace]] industry and the luxury goods market, and could be seen in many products currently manufactured using [[aluminium]] and specialist grades of [[steel]].
Common titanium [[alloy]]s are made by reduction. For example, cuprotitanium (rutile with [[copper]] added is reduced), ferrocarbon titanium ([[ilmenite]] reduced with [[coke (fuel)|coke]] in an electric furnace), and manganotitanium ([[rutile]] with manganese or manganese oxides) are reduced.<ref name="TI_Encarta2005"/>
::2[[Ilmenite|TiFeO<sub>3</sub>]] + 7[[Chlorine|Cl<sub>2</sub>]] + 6[[Carbon|C]] (900 °C) → 2[[Titanium tetrachloride|TiCl<sub>4</sub>]] + 2[[Iron(III) chloride|FeCl<sub>3</sub>]] + 6[[Carbon monoxide|CO]]
::[[Titanium tetrachloride|TiCl<sub>4</sub>]] + 2[[Magnesium|Mg]] (1100 °C) → 2[[Magnesium chloride|MgCl<sub>2</sub>]] + '''Ti'''
About 50 grades of titanium and titanium alloys are designated and currently used, although only a couple of dozen are readily available commercially.<ref>{{cite book |title=TITANIUM: A Technical Guide |year=1988 |author=Matthew J. Donachie, Jr. |publisher=ASM International |location=Metals Park, OH|pages=p.16, Appendix J |id=ISBN 0871703092}}</ref> The [[ASTM International]] recognizes 31 Grades of titanium metal and alloys, of which Grades 1 through 4 are commercially pure (unalloyed). These four are distinguished by their varying degrees of 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 (highest tensile strength with an oxygen content of 0.40%).<ref name="BuildingBlocks455"/> The remaining grades are alloys, each designed for specific purposes, be it ductility, strength, hardness, electrical resistivity, [[Creep (deformation)|creep]] resistance, resistance to corrosion from specific media, or a combination thereof.<ref>{{cite book |title=Annual Book of ASTM Standards (Volume 02.04: Non-ferrous Metals) |year=2006 |author=[[ASTM International]] |publisher=ASTM International |location=[[West Conshohocken, PA]] |pages=section 2 |id=ISBN 080314086X}} {{cite book |title=Annual Book of ASTM Standards (Volume 13.01: Medical Devices; Emergency Medical Services) |year=1998 |author=[[ASTM International]] |publisher=ASTM International |location=[[West Conshohocken, PA]] |pages=sections 2 & 13 |id=ISBN 080312452X}}</ref>
The grades covered by ASTM and other 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.<ref>{{cite book |title=TITANIUM: A Technical Guide |year=1988 |author=Matthew J. Donachie, Jr. |publisher=ASM International |location=Metals Park, OH|pages=pgs.13–16, Appendices H and J |id=ISBN 0871703092}}</ref>
In terms of fabrication, all [[welding]] of titanium must be done in an inert atmosphere of [[argon]] or [[helium]] in order to shield it from contamination with atmospheric gases such as oxygen, [[nitrogen]], or [[hydrogen]].<ref name="EncyChem"/><!-- page 734 --> Contamination will cause a variety of conditions, such as embrittlement, which will reduce the integrity of the assembly welds and lead to joint failure.
Commercially pure flat product (sheet, plate) can be formed readily, but processing must take into account the fact that the metal has a "memory" and tends to spring back. This is especially true of certain high-strength alloys.<ref>{{cite book |title=AWS G2.4/G2.4M:2007 Guide for the Fusion Welding of Titanium and Titanium Alloys |year=2006 |author=[[American Welding Society]] |publisher=American Welding Society |location=Miami}} [http://www.awspubs.com/product_info.php?products_id=408 ''Abstract'']</ref><ref>{{cite book |title=Titanium design and fabrication handbook for industrial applications |year=1997 |author=[[Titanium Metals Corporation]] |publisher = Titanium Metals Corporation |location=Dallas |url=http://www.timet.com/design&fabframe.html}}</ref> The metal can be machined using the same equipment and via the same processes as [[stainless steel]].<ref name="EncyChem"/><!-- page 734 -->
==Applications==
Titanium is used in [[steel]] as an alloying element ([[ferro-titanium]]) to reduce [[Crystallite|grain size]] and as a deoxidizer, and in [[stainless steel]] to reduce [[carbon]] content.<ref name="TIEB2005"/> Titanium is often alloyed with [[aluminium]] (to refine grain size), [[vanadium]], [[copper]] (to harden), [[iron]], [[manganese]], [[molybdenum]], and with other metals.<ref name="ECE738">{{cite book |last=Hampel |first=Clifford A. |year=1968 |title=The Encyclopedia of the Chemical Elements |pages=p. 738 |publisher=Van Nostrand Reinhold |id=ISBN 0442155980}}</ref> Applications for titanium mill products (sheet, plate, bar, wire, forgings, castings) can be found in industrial, aerospace, recreational, and emerging markets. Powdered titanium is used in [[pyrotechnics]] as a source of bright-burning particles.
===Pigments, Additives and Coatings===
[[Image:Titanium(IV) oxide.jpg|thumb|left|Titanium dioxide is the most commonly used compound of titanium]]
About 95% of titanium ore extracted from the Earth is destined for refinement into [[titanium dioxide]] ({{chem|Ti[[oxygen|O]]|2}}), an intensely white permanent [[pigment]] used in [[paint]]s, [[paper]], [[toothpaste]], and [[plastics]].<ref name="USGS_Minerals">{{cite web |url=http://minerals.usgs.gov/minerals/pubs/commodity/titanium/ |title=USGS Minerals Information: Titanium|author=[[United States Geological Survey]] |date=[[2006-12-21]] |accessdate=2006-12-29}}</ref> It is also used in [[cement]], in [[gemstone]]s, as an optical opacifier in [[paper]],<ref>{{cite book |last=Smook |first=Gary A. |title=Handbook for Pulp & Paper Technologists (3rd edition) |publisher=Angus Wilde Publications |year=2002 |id=ISBN 0-9694628-5-9 |
pages=p. 223}}</ref> and a strengthening agent in graphite composite fishing rods and golf clubs.
{{chem|TiO|2}} powder is chemically inert, resists fading in sunlight, and is very opaque: this allows it to impart a pure and brilliant white color to the brown or gray chemicals that form the majority of household plastics.<ref name="HistoryAndUse"/> In nature, this compound is found in the [[mineral]]s [[anatase]], [[brookite]], and [[rutile]].<ref name="TIEB2005"/>
Paint made with titanium dioxide does well in severe temperatures, is somewhat self-cleaning, and stands up to marine environments.<ref name="HistoryAndUse"/> Pure titanium dioxide has a very high [[refractive index|index of refraction]] and an [[optical dispersion]] higher than [[diamond]].<ref name="LANL"/>
Recently, it has been put to use in air purifiers (as a filter coating), or in film used to coat windows on buildings which when exposed to [[UV light]] (either solar or man-made) and moisture in the air produces reactive redox species like hydroxyl radicals that can purify the air or keep window surfaces clean.<ref>{{cite conference |author=Stevens, Lisa; Lanning, John A.; Anderson, Larry G.; Jacoby, William A.; Chornet, Nicholas |url=http://carbon.cudenver.edu/~landerso/98mp9b06.htm |title=Photocatalytic Oxidation of Organic Pollutants Associated with Indoor Air Quality |booktitle=Air & Waste Management Association 91st Annual Meeting & Exhibition, San Diego |date=June 14 – 18, 1998 |accessdate=2006-12-26}}</ref>
===Aerospace and marine===
[[Image:A380-trent900.JPG|thumb|left|The four engines alone on the [[Airbus A380]] use about 26 metric tons (57,000 pounds) of titanium]]
Due to their high [[tensile strength]] to density ratio,<ref name="TICE6th"/> high corrosion resistance<ref name="LANL"/>, and ability to withstand moderately high temperatures without [[Creep (deformation)|creeping]], titanium [[alloy]]s are used in [[aircraft]], [[armor plating]], [[navy|naval]] ships, [[spacecraft]], and [[missile]]s.<ref name="HistoryAndUse"/><ref name="LANL"/> For these applications titanium alloyed with aluminium, vanadium, and other elements is used for a variety of components including critical structural parts, fire walls, [[landing gear]], exhaust ducts (helicopters), and hydraulic systems. In fact, about two thirds of all titanium metal produced is used in aircraft engines and frames.<ref name="BuildingBlocks455"/> The [[SR-71 Blackbird|SR-71 "Blackbird"]] was one of the first aircraft to make extensive use of titanium within its structure, paving the way for its use in modern fighter and commercial aircraft. An estimated 59 metric tons (130,000 pounds) are used in the [[Boeing 777]], 45 in the [[Boeing 747|747]], 18 in the [[Boeing 737|737]], 32 in the [[Airbus A340]], 18 in the [[A330]], and 12 in the [[Airbus A320#A320|A320]]. The [[Airbus A380|A380]] may use 146 metric tons, including about 26 tons in the engines.<ref>{{cite web |last=Sevan |first=Vardan |url=http://www.sevanco.net/news/full_story.php?id=1122 |title=Rosoboronexport controls titanium in Russia |date=[[2006-09-23]] |publisher=Sevanco Strategic Consulting |accessdate=2006-12-26}}</ref> In engine applications, titanium is used for rotors, compressor blades, hydraulic system components, and [[nacelles]]. The [[titanium 6AL-4V]] alloy accounts for almost 50% of all alloys used in aircraft applications.<ref>{{cite book |title=TITANIUM: A Technical Guide |year=1988 |author=Matthew J. Donachie, Jr. |publisher=ASM International |location=Metals Park, OH|pages=p.13, |id=ISBN 0871703092}}</ref>
Due to its high corrosion resistance to [[sea water]], titanium is used to make propeller shafts and rigging and in the [[heat exchanger]]s of [[desalination plant]]s;<ref name="LANL"/> in heater-chillers for salt water [[aquarium]]s, fishing line and leader, and for divers' knives. Titanium is used to manufacture the housings and other components of ocean-deployed surveillance and monitoring devices for scientific and military use. The former [[Soviet Union]] developed techniques for making submarines largely out of titanium, which became both the fastest and deepest diving submarines ever made.<ref>{{cite web | title = GlobalSecurity | publisher = [[GlobalSecurity.org]] | date = April 2006 | url = http://www.globalsecurity.org/military/world/russia/705.htm | accessdate = 2008-04-23}}</ref>
Titanium commercial aerospace requirements (including engine components [''e.g., blades, discs, rings and engine cases''] and airframe components [''e.g., bulkheads, tail sections, landing gear, wing supports and fasteners'']) for the manufacture of:
'''Boeing''' (including both the airframes and engines)
*B787 – ''295,000 pounds (133.8 tonne) of titanium''
*B777 – ''130,000 pounds (59 tonne) of titanium''
*B747 – ''100,000 pounds (45.4 tonne) of titanium''
*B737 – ''40,000 pounds (18.1 tonne) of titanium''
'''Airbus''' (including both the airframes and engines)
*A380 – ''320,000 pounds (145.1 tonne) of titanium''
*A350 – ''165,000 pounds (74.8 tonne) of titanium (estimated minimal requirement)''
*A340 – ''70,000 pounds (31.8 tonne) of titanium''
*A330 – ''40,000 pounds (18.1 tonne) of titanium''
*A320 – ''26,000 pounds (11.8 tonne) of titanium''
''Source: [http://sec.gov/Archives/edgar/data/1011657/000101165708000002/form_10k.htm TIMET 2007 Form 10-K] (converted from metric tons to pounds)''
===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 downhole and [[nickel]] [[hydrometallurgy]] applications due to their high strength '''titanium Beta C''', corrosion resistance, or combination of 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).<ref>{{cite book |title=TITANIUM: A Technical Guide |year=1988 |author=Matthew J. Donachie, Jr. |publisher=ASM International |location=Metals Park, OH|pages=pgs. 11–16 |id=ISBN 0871703092}}</ref> Other applications include: [[ultrasonic welding]], [[wave soldering]],<ref>{{cite book |title= Industrial Application of Titanium and Zirconium
|publisher=ASTM International |author= E.W. Kleefisch, Editor | id= ISBN 0803107455|location= West Conshohocken, PA|url= http://www.astm.org/cgi-bin/SoftCart.exe/BOOKSTORE/PUBS/943.htm?E+mystore|year=1981}}</ref> and [[sputtering targets]].<ref>{{cite book |title=Handbook of Hard Coatings |publisher=William Andrew Inc. |pages=Ch. 8 |author=Rointan F. Bunshah, Editor | id=ISBN 0815514387|location=Norwich, NY|url= http://www.williamandrew.com/titles/1438.htm|year=2001}}</ref>
===Consumer and architectural===
[[Image:GuggenheimBilbao.jpg|thumb|The [[Guggenheim Museum Bilbao]] is sheathed in titanium panels.]]
[[Image:Ti covered watches.jpg|thumb|Watch with titanium cover]]
Titanium metal is used in automotive applications, particularly in automobile or motorcycle racing, where weight reduction is critical while maintaining high strength and rigidity. The metal is generally too expensive to make it marketable to the general consumer market, other than high-end products. Late model [[Chevrolet Corvette|Corvette]]s have been available with titanium exhausts,<ref>{{cite web |url=http://www.iglou.com/corvette/specs/2001/exhaust.htm |title=Titanium Exhausts |accessdate=2006-12-26 |author=National Corvette Museum |date=2006}}</ref> and racing bikes are frequently outfitted with titanium mufflers. Titanium alloy is used for the connecting rods in the engine of the 2006 and later Corvette Z06. Other automotive uses include piston rods and hardware (bolts, nuts, etc.).
The [[Parker Pen Company]] used titanium to form the T-1 fountain pen, later expanded to T-1 ball pens and rollerballs. The T-1 fountain pen was introduced in 1970 and the T-1 rollerball and ball pen in 1971. Production was stopped in 1972 due to the high cost of manufacturing titanium. Parker T-1's are prized for their collectibility by collectors.
[[Hammer]] heads made of titanium were introduced in 1999. Their light weight allows for a longer handle which increases the velocity of the head and results in more energy being delivered to the nail, all while decreasing arm fatigue. Titanium also decreases the shock transferred to the user because a titanium head generates about 3% recoil compared to a steel head that generates about 27%.
Titanium is used in many sporting goods: [[tennis racket]]s, [[golf club (equipment)|golf clubs]], [[lacrosse]] stick shafts; [[cricket]], hockey, lacrosse, and football helmet grills; and [[bicycle]] frames and components. Titanium alloys are also used in [[glasses|spectacle]] frames. This results in a rather expensive, but highly durable and long lasting frame which is light in weight and causes no skin allergies. Many [[Backpacking (wilderness)|backpackers]] use titanium equipment, including cookware, eating utensils, lanterns, and tent stakes. Though slightly more expensive than traditional steel or aluminium alternatives, these titanium products can be significantly lighter without compromising strength. Titanium is also favored for use by [[farrier]]s, since it is lighter and more durable than [[steel]] when formed into [[horseshoes]]. Titanium horseshoes can be found in [[horse racing]], and are used by many [[Amish]] horse owners, who rely entirely on horse-drawn carriages for transportation.
Because of its durability, titanium has become more popular for designer jewelry in recent years, whereas until recently the metal was too difficult to work into the intricate shapes with the precision necessary for fine [[jewelry]]. Today, titanium rings — including [[engagement ring]]s and [[Wedding ring|wedding bands]] — are one of the fastest growing segments of the titanium jewelry market, in part due to the ability of the metal to be grooved, inlaid, and carved without losing strength. Some titanium jewelry also incorporates [[diamonds]] or other gemstones, typically in close settings such as bezels, flush, or tension designs. Its inertness again 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 used in watchmaking for the production of [[watch]] cases. Watchmakers appreciate titanium for its durability, light weight, dent- and corrosion- resistance. Titanium watches are often coated with a protective material to make the surface more scratch-resistant.<ref>[http://watches.infoniac.com/index.php?page=post&id=62 Titanium in watchmaking]</ref>
Titanium has occasionally been used in architectural applications: the 120 foot (40 m) memorial to [[Yuri Gagarin]], the first man to travel in space, in [[Moscow]], is made of titanium for the metal's attractive color and association with rocketry.<ref>{{cite encyclopedia |url=http://encarta.msn.com/encyclopedia_761571506/Gagarin_Yuri_Alekseyevich.html |title=Yuri Gagarin |encyclopedia=[[Microsoft Encarta]] |year=2006 |accessdate=2006-12-26}}</ref> 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. Other construction uses of titanium sheathing include the [[Frederic C. Hamilton Building]] in ([[Denver]], [[Colorado]])<ref>{{cite web |url=http://www.designbuild-network.com/projects/dam/ |title=Denver Art Museum, Frederic C. Hamilton Building |accessdate=2006-12-26 |publisher=SPG Media |date=2006}}</ref> and the 350 foot (107 m) [[Monument to the Conquerors of Space]] in [[Moscow]].
Due to its superior strength and light weight when compared to other metals traditionally used in firearms ([[steel]], [[stainless steel]], and [[aluminium]]), and advances in metal-working techniques, the use of titanium has become more widespread in the manufacture of firearms. Primary uses include [[pistol]] frames and [[revolver]] cylinders.
===Medical===
[[Image:Hip prosthesis.jpg|thumb|right|A titanium hip prosthesis, with a [[ceramic]] head and [[polyethylene]] acetabular cup.]]
[[Image:Lateralcephplated.JPG|thumb|right|This left lateral cephalametric [[radiograph]] shows a profile of the human skull. A fracture of the [[orbit (anatomy)|eye socket]] was repaired by stabilizing the fractured bones with small [[titanium]] plates and screws.]]
Because it is biocompatible (non-toxic and is not rejected by the body), titanium is used in a gamut of medical applications including surgical implements and implants, such as hip balls and sockets ([[joint replacement]]) that can stay in place for up to 20 years. Titanium has the inherent property to [[osseointegration|osseointegrate]], enabling use in [[dental implants]] that can remain in place for over 30 years. This property is also useful for orthopedic implant applications.<ref name="BuildingBlocks451-3"/>
<!-- NEEDS CITE
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, eventually leading to joint degradation. /NEEDS CITE -->
Since 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 (physics)|plasma]] arc which removes the surface atoms, exposing fresh titanium that is instantly oxidized.<ref name="BuildingBlocks451-3"/> Titanium is also 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 important.
Its inertness and ability to be attractively colored makes it a popular metal for use in [[body piercing]].<ref>{{cite web |url=http://hospitals.unm.edu/AboutUs/Healthsmart/Fall06.pdf |title=Body Piercing Safety |accessdate=2006-12-30}}</ref> Titanium may be [[Anodising|anodized]] to produce various colors.<ref>{{cite web |url=http://electrochem.cwru.edu/ed/encycl/art-a02-anodizing.htm |title=Electrochemistry Encyclopedia |author=Alwitt, Robert S. |date=2002 |accessdate=2006-12-30}}</ref> A number of artists work with titanium to produce artworks such as sculptures, decorative objects, and furniture.
== Compounds ==
The +4 [[oxidation state]] dominates in titanium chemistry, but compounds in the +3 [[oxidation state]] are also common. Because of this high oxidation state, many titanium compounds have a high degree of [[covalent bond]]ing.
[[Star sapphire (jewel)|Star sapphire]]s and [[ruby|rubies]] get their [[Asterism (gemmology)|asterism]] from the [[titanium dioxide]] impurities present in them.<ref name="BuildingBlocks451-3"/> [[Titanate]]s are compounds made with titanium dioxide. [[Barium titanate]] has [[piezoelectric]] properties, thus making it possible to use it as a transducer in the interconversion of [[sound]] and [[electricity]].<ref name="TICE6th"/> [[Ester]]s of titanium are formed by the reaction of [[alcohol]]s and titanium tetrachloride and are used to waterproof [[Cloth|fabric]]s.<ref name="TICE6th"/>
[[Image:Titanium nitride coating.jpg|thumb|100px|TiN coated drill bit]]
[[Titanium nitride]] (TiN) is often used to coat cutting tools, such as [[drill bit]]s. It also finds use as a gold-coloured decorative finish, and as a [[Copper-based chips#Barrier metal|barrier metal]] in [[semiconductor fabrication]].
[[Titanium tetrachloride]] (titanium(IV) chloride, TiCl<sub>4</sub>, sometimes called "Tickle") is a colourless liquid which is used as an intermediate in the manufacture of titanium dioxide for paint. It is widely used in [[organic chemistry]] as a [[Lewis acid]], for example in the [[Mukaiyama aldol condensation]]. Titanium also forms a lower chloride, [[titanium(III) chloride]] (TiCl<sub>3</sub>), which is used as a [[reducing agent]].
[[Titanocene dichloride]] is an important catalyst for carbon-carbon bond formation. [[Titanium isopropoxide]] is used for [[Sharpless epoxidation]]. Other compounds include [[titanium bromide]] (used in metallurgy, [[superalloy]]s, and high-temperature electrical wiring and coatings) and [[titanium carbide]] (found in high-temperature cutting tools and coatings).<ref name="HistoryAndUse"/>
== Isotopes ==
{{main|Isotopes of titanium}}
Naturally occurring titanium is composed of 5 stable [[isotope]]s: <sup>46</sup>Ti, <sup>47</sup>Ti, <sup>48</sup>Ti, <sup>49</sup>Ti, and <sup>50</sup>Ti, with <sup>48</sup>Ti being the most abundant (73.8% [[natural abundance]]). Eleven [[radioisotope]]s have been characterized, with the most stable being <sup>44</sup>Ti with a [[half-life]] of 63 years, <sup>45</sup>Ti with a half-life of 184.8 minutes, <sup>51</sup>Ti with a half-life of 5.76 minutes, and <sup>52</sup>Ti with a half-life of 1.7 minutes. All of the remaining [[radioactive]] isotopes have half-lives that are less than 33 seconds and the majority of these have half-lives that are less than half a second.<ref name="EnvChem"/>
The isotopes of titanium range in [[atomic weight]] from 39.99 [[unified atomic mass unit|u]] (<sup>40</sup>Ti) to 57.966 u (<sup>58</sup>Ti). The primary [[decay mode]] before the most abundant stable isotope, <sup>48</sup>Ti, is [[electron capture]] and the primary mode after is [[beta emission]]. The primary [[decay product]]s before <sup>48</sup>Ti are element 21 ([[scandium]]) isotopes and the primary products after are element 23 ([[vanadium]]) isotopes.<ref name="EnvChem"/>
== Precautions ==
[[Image:Kopiva.JPG|thumb|Nettle contains up to 80 parts per million of titanium]]
Titanium is non-toxic even in large doses and does not play any natural role inside the [[human body]]. An estimated 0.8 milligrams of titanium is ingested by humans each day but most passes through without being absorbed. It does, however, have a tendency to [[bio-accumulate]] in tissues that contain [[silica]]. An unknown mechanism in [[plant]]s may use titanium to stimulate the production of [[carbohydrate]]s 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.<ref name="BuildingBlocks451-3"/>
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]]-based methods to extinguish fires are ineffective on burning titanium; [[fire classes#Class-D fires|Class D]] dry powder fire fighting agents must be used instead.<ref name="HistoryAndUse"/>
Even bulk titanium metal is susceptible to fire, when it is heated to its melting point. A number of titanium fires occur during breaking down devices containing titanium parts with [[cutting torch]]es.
When used in the production or handling of [[chlorine]], care must be taken to use titanium only in locations where it will not be exposed to dry chlorine gas which can result in a titanium/chlorine fire. Care must be taken even when titanium is used in wet chlorine due to possible unexpected drying brought about by extreme weather conditions.
Titanium can catch fire when a fresh, non-oxidized surface gets in contact with [[liquid oxygen]]. Such surfaces can appear when the oxidized surface is struck with a hard object, or when a mechanical strain causes the emergence of a crack. This poses the possible limitation for its use in liquid oxygen systems, such as those found in the aerospace industry.
[[Salt]]s of titanium are often considered to be relatively harmless, but its chlorine compounds, such as [[titanium(II) chloride|TiCl<sub>2</sub>]], [[titanium(III) chloride|TiCl<sub>3</sub>]], and [[titanium(IV) chloride|TiCl<sub>4</sub>]], have presented several unusual hazards. The dichloride takes the form of [[pyrophoric]] black crystals, and the tetrachloride is a volatile fuming liquid. All of titanium's chlorides are [[corrosive]].
== See also ==
* [[Titanium alloy]]
* [[Titanium nitride|Titanium coating]]
* [[:category:Titanium compounds|Titanium compounds]]
* [[Titanium in Africa]]
* [[:category:Titanium minerals|Titanium minerals]]
* [[VSMPO-AVISMA]]
* [[Titanium Metals Corporation]]
==References==
{{reflist|2}}
{{refbegin}}
*{{cite journal |last=Flower |first=Harvey M. |title=Materials Science: A moving oxygen story |url=http://www.nature.com/nature/journal/v407/n6802/full/407305a0.html |journal=[[Nature (journal)|Nature]] |volume=407 |year=2000 |pages=305 |doi=10.1038/35030266}}
*{{cite book |last=Stwertka |first=Albert |title=Guide to the Elements (Revised Edition) |publisher=Oxford University Press |location=Oxford |year=1998 |id=ISBN 0-19-508083-1}}
*{{cite web |url=http://www.webelements.com/webelements/elements/text/Ti/index.html |title=Chemistry: Periodic table: Titanium |accessdate=2006-12-10 |date=2006 |last=Winter |first=Mark |publisher=WebElements}}
*''Book of Titanium'', Ehsan Ghandhari (2007)
{{refend}}
== External links ==
{{Spoken Wikipedia|Titanium.ogg|2005-08-25}}
{{wiktionary|titanium}}
{{Commons|Titanium}}
* [http://www.techreview.com/read_article.aspx?id=16963&ch=nanotech A Cleaner, Cheaper Route to Titanium]
* [http://www.titanium.org International Titanium Association]
* [http://www.msm.cam.ac.uk/phase-trans/2003/titanium.movies/titanium.html Metallurgy of Titanium and its Alloys, Cambridge University]
* [http://www.indexmundi.com/en/commodities/minerals/titanium/titanium_table15.html World Production of Titanium Concentrates, by Country]
* [http://www.stainless-steel-world.com/titanium/ShowPage.aspx?pageID=165 technical information on titanium]
* [http://www.popsci.com/popsci/how20/85f145ef7d2f6110vgnvcm1000004eecbccdrcrd.html Truth in Sparks: Titanium or Plain Ol' Steel?] Popular Science Magazine
{{clear}}
{{compact periodic table}}
[[Category:Chemical elements]]
[[Category:Transition metals]]
[[Category:Titanium]]
[[Category:Pyrotechnic fuels]]
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