|Boiling Point: 3560°K, 3287°C, 5949°F
Melting Point: 1933°K, 1660°C, 3020°F
Electrons Energy Level: 2, 8, 10, 2
Isotopes: 17 + 5 Stable
Heat of Vaporization: 421 kJ/mol
Heat of Fusion: 15.45 kJ/mol
Density: 4.54 g/cm3 @ 300°K
Specific Heat: 0.52 J/g°K
Atomic Radius: 2Å
Ionic Radius: 0.605Å
Electronegativity: 1.54 (Pauling); 1.32 (Allrod Rochow)
Vapor Pressure: 0.49 Pa @ 1660°C
1s2 2s2p6 3s2p6d2 4s2
Titanium was discovered combined in a mineral in Cornwall, England in 1791 by amateur geologist William Gregor, the then vicar of Creed village. He recognized the presence of a new element in ilmenite when he found a 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. 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 Creel's Annalen.
Martin Heinrich Klaproth named titanium for the Titans of Greek mythology.
Around the same time, Franz Joseph Muller also produced a similar substance, but could not identify it. The oxide was independently rediscovered in 1795 by German chemist Martin Heinrich Klaproth in Rutile from Hungary. 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 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. Pure metallic titanium (99.9%) was first prepared in 1910 by Matthew A. Hunter by heating TiCl4 with sodium in a steel bomb at 700 800°C in the Hunter process. Titanium metal was not used outside the laboratory until 1946 when William Justin Kroll proved that it could be commercially produced by reducing titanium tetracchloride with magnesium in what came to be known as the Kroll process. Although research continues into more efficient and cheaper processes (FFC Cambridge, e.g.), the Kroll process is still used for commercial production.
Titanium of ultra high purity was made in small quantities when Anton Eduard van Arkel and Jan Hendrik de Boer discovered the iodide, or crystal bar, 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. In the USA, the DOD realized the strategic importance of the metal and supported early efforts of commercialization. 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. Today, the world's largest producer, Russian-based VSMPO-Avisma, is estimated to account for about 29% of the world market share.
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 power. 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.
A metallic element, titanium is recognized for its high strength-to-weight ratio. It is a light, strong metal with low density that, when pure, is quite ductile (especially in an oxygen-free environment), 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 strengths of about 63,000 psi, equal to that of steels alloys, but are 45% lighter. Titanium is 60% heavier than aluminum but more than twice as strong as the most commonly used 6061-T6 aluminum alloy. Certain titanium alloys (e.g., Beta C) achieve tensile strengths of over 200,000 psi (1.4 GPa). However, titanium loses strength when heated above 430°C (800°F)
It is fairly hard (although by no means as hard as some grades of heat-treated steel) and can be tricky to machine due to the fact that it will 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.
The metal is a dimorphic allotrope with the hexagonal alpha form changing into the body-centered cubic (lattice) beta form at 882°C (1,619°F). The heat capacity 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.
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 acids, moist chlorine gas, and by common salt solutions. Pure titanium is not soluble in water but is soluble in concentrated acids.
This metal forms a passive and protective oxide coating (leading to increased corrosion-resistance) when exposed to elevated temperatures in air, but at room temperatures it resists tarnishing. When it first forms, this protective layer is only 1 to 2 nanometers thick but continues to slowly grow; reaching a thickness of 25 nanometers in four years.
Titanium burns when heated in air 610°C (1,130°F) or higher, forming titanium dioxide. 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 nitrade, which causes embrittlement). Titanium is resistant to dilute sulfuric and hydrochloric acid, along with chlorine gas, chloride solutions, and most organic acids. It is paramagnetic (weakly attracted to magnets) and has fairly low electrical and thermal conductivity.
Experiments have shown that natural titanium becomes radioactive after it is bombarded with deuterons, emitting mainly positrons and hard gamma rays. When it is red hot the metal combines with oxygen, and when it reaches 550°C (1,022°F) it combines with chlorine. It also reacts with the other halogens and absorbs hydrogen.
Titanim is always bonded to other elements in nature. It is the ninth-most abundant element in the Earth's crust (0.63% by mass) and the ourth-most abundant metal. It is present in most igneous rocks and in sediments derived from them (as well as in living things and natral bodies of water. In fact, of the 801 types of igneous rocks analyzed by the United States Geological Survey, 784 contian titnium. Its proportion in soils is approximately 0.5 to 1.5%.
It is widely distributed and occurs primarily in the minerals 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. Significant titanium-bearing ilmenite deposits exist in western Australia, Canada, New Zealand, Norway, 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 tons of the metal and 4.3 million tons of titanium dioxide. Total known reserves of titanium are estimated to exceed 600 million tons.
Titanium is contained in meterorites and has been detected in the sun and in M-type stars; the coolest type of star with a surface temperature of 3,200°C (5,792°F). Rocks brought back from the moon during the Apollo 17 mission are composed of 12.1% TiO2. It is also found in coal, ash, plants, and even the human body.
Production and Fabrication
The processing of titanium metal occurs in 4 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, whereby 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 air at high temperatures it cannot be produced by reduction of its dioxide. Titanium metal is therefore produced commercially by the Kroll process, a complex and expensive batch process. (The relatively high market value of titanium is mainly due to its processing, which sacrifices another expensive metal, magnesium. 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 TiCl4. This is condensed and purified by fractional distillation and then reduced with 800°C molten magnesium in an argon atmosphere.
A more recently developed method, the FFC Cambridge process, 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 aluminum and specialist grades of steel.
Common titanium alloys are made by reduction. For example; cuprotitanium (rutile with copper added is reduced), ferrocarbon titanium (ilmenite reduced with coke in an electric furnace), and manganotitanium (rutile with manganese or manganese oxides) are reduced.
2TiFeO3 + 7Cl2 + 6C (900°C) 2TiCl4 + 2FeCl3 + 6CO
TiCl4 + 2Mg (1100°C) 2MgCl2 + Ti
About 50 grades of titanium and titanium alloys are designated 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 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%). The remaining grades are alloys, each designed for specific purposes, be it ductility, strength, hardness, electrical resistivity, creep resistance, resistance to corrosion from specific media, or a combination thereof.
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.
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. 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. The metal can be machined using the same equipment and via the same processes as stainless steel.
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 aluminum (to refine grain size), vanadium, copper (to harden), iron, manganese, molybdenum, and with other metals. Applications for titanium mill products (sheet, plate, bar, wire, forgings, castings) can be found in industrial, aerospace, recreational and emerging markets.
Pigments, Additives and Coatings
About 95% of titanium ore extracted from the Earth is destined for refinement into titanium dioxide (TiO2), an intensely white permanent pigment used in paints, paper, toothpaste, and plastics. It is also used in cement, in gemstones, as an optical opacifier in paper, and a strengthening agent in graphite composite fishing rods and golf clubs.
TiO2 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. In nature, this compound is found in the minerals anatase, brookite, and rutile. Paint made with titanium dioxide does well in severe temperatures, is somewhat self-cleaning, and stands up to marine environments. Pure titanium dioxide has a very high index of refraction and an optical dispersion higher than diamond.
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.
Aerospace and Marine
Because of its high tensil strength (even at high temperatures), light weight, extraordinary corrosion resistance, and ability to withstand extreme temperatures, titanium alloys are used in aircraft, armor plating, naval ships, spacecraft and missiles. For these applications, titanium alloyed with aluminum, 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. An estimated 58 tons are used in the boeing 777, 43 in the 747, 18 in the 737, 24 in the Airbus A340, 17 in the A330 and 12 in the A320. The A380 may use 77 tons, including about 11 tons in the engines. In engine applications, titanium is used for rotors, turbine blades, hydraulic system components and nacelles. The titanium 6AL-4V alloy accounts for almost 50% of all alloys used in aircraft applications.
Due to excellent corrosion resistance to sea water, titanium is used to make propeller shafts and rigging and in the heat exchanger of desalination plants; in heater-chillers for salt water aquariums, fishing line and leader, and diver knives as well. Titanium is used to manufacture the housings and other components of ocean-deployed surveillance and monitoring devices for scientific and military use.
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) or corrosion resistance or combination of both. The pulp and paper industry uses titanium in process equipment exposed to corrosive media such as chlorine (in the bleachery). Other applications include: ultrasonic welding, wave soldering, and sputtering targets.
Consumer and Architectural
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 Corvettes have been available with titanium exhausts, and racing bikes are frequently outfitted with titanium mufflers. Other automotive uses include piston rods and hardware (bolts, nuts, etc.).
Titanium is used in many sporting goods; tennis rackets, golf clubs, lacrosse stick shafts; cricket, hockey and football helmet grills, bicycle frames and components. Titanium alloys are also used in optical glass 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 backpackers use titanium equipment, including cookware, eating utensils, lanterns and tent stakes. Though slightly more expensive than traditional steel or aluminum alternatives, these titanium products can be significantly lighter without compromising strength.
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. The Guggenheim Museum Bilbao and the Cerrito 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.
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 osseointegrate, enabling use in dental implants that can remain in place for over 30 years. This property is also useful for orthopedic implant applications.
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 arc which removes the surface atoms, exposing fresh titanium that is instantly oxidized. Titanium is also used for the surgical instruments used in image-guided surgery, as well as wheelchairs, crutches, and any other product 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. Titanium may be anodized to produce various colors. A number of artists work with titanium to produce artworks such as sculptures, decorative objects and furniture.
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 bonding.
Star sapphires and rubies get their asterism from the titanium dioxide impurities present in them. Titanates 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. Esters of titanium are formed by the reaction of alcohols and titanium tetrachloride and are used to waterproof fabrics.
Titanium nitride (TiN) is often used to coat cutting tools, such as drill bits. It also finds use as a gold-colored decorative finish, and as a barrier metal in semicondictor fabrication.
Titanium tetrachloride (titanium (IV) chloride, TiCl4, sometimes called "Tickle") is a colorless 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 Mukaiyana aldol condensation. Titanium also forms a lower chloride, titanium (III) chloride (TiCl3), 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, superalloys, and high-temperature electrical wiring and coatings) and titanium carbide (found in high-temperature cutting tools and coatings).
|Rutile, TiO2||Ilmenite, FeTiO3|
Naturally occurring titanium is composed of 5 stable isotopes; 46Ti, 47Ti, 48Ti, 49Ti and 50Ti with 48Ti being the most abundant (73.8% natural abundance). Seventeen radioisotopes have been characterized, with the most stable being 44Ti with a half-life of 63 years, 45Ti with a half-life of 184.8 minutes, 51Ti with a half-life of 5.76 minutes, and 52Ti with a half-life of 1.7 minutes. All of the remaining radioactive isotopes have half-lifes that are less than 33 seconds and the majority of these have half-lifes that are less than half a second.
The isotopes of titanium range in atomic weight from 39.99 amu (40Ti) to 57.966 amu (58Ti). The primary decay mode before the most abundant stable isotope, 48Ti, is electron capture and the primary mode after is beta emission. The primary decay products before 48Ti are element 21 (scandium) isotopes and the primary products after are element 23 (vanadium) isotopes.
There are two allotropic forms and five naturally occurring isotopes of this element; 46Ti through 50Ti with 48Ti being the most abundant. (73.8%). Titanium's properties are chemically and physically similar to zirconium.
|Ti61||60.982|| 10 ms|
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 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 horsetalil and nettle contain up to 80 ppm.
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; Class D dry powder fire fighting agents must be used instead.
Salts of titanium are often considered to be relatively harmless but its chlorine compounds, such as TiCl2, TiCl3 and TiCl4, have 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.
A final bit of titanium trivia -- titanium is the only element that will burn in an atmosphere of pure nitrogen.
|Ionization Energy (eV): 6.828 eV
Estimated Crustal Abundance: 5.65×103 milligrams per kilogram
Estimated Oceanic Abundance: 1×10-3 milligrams per liter