Ti - Titanium

Properties

Titanium is a hard, lightweight, lustrous, silvery metal, which heads Group 4 of the Periodic Table. Titanium is a transition metal, and is the 9th most abundant element in the Earth’s crust, making up about 0.6% of the Earth’s mass. Despite it being lightweight, titanium is unusually strong and virtually immune to the usual kinds of metal fatigue. It also has an extraordinary resistance to corrosion. Titanium has this property thanks to a thin layer of titanium dioxide making it impervious to most extreme conditions. This metal is completely non-rusting and non-allergenic, giving it useful applications, such as within the human body. Titanium is as strong as steel, yet 45% lighter, meaning that where cost is not the overriding factor, titanium is advantageous over steel.

History

The first titanium mineral was discovered in 1791 by an amateur mineralogist named Reverend William Gregor. Gregor, whilst walking next to a stream, came across a black sand in a remote village in Cornwall, South-West England. What had interested him most about this sand was that it was attracted to a magnet. Upon analysis, he was able to determine that it contained two metal oxides, the first being iron oxide (which explained why the substance had magnetic properties) and an unknown metal oxide, which he was unable to determine. Gregor then realised that this unknown metal oxide was that of a new element. Had he been able to isolate this new metal, his intentions were to name it Menaccin. Four years later, a German scientist, Martin Heinrich Klaproth of Berlin, re-discovered this same element whilst analysing a red ore, a form of rutile (TiO2). It was Klaproth who gave this new element the name titanium, derived from the Titans of Greek mythology. But once again, Klaproth had only been able to obtain the metal oxide. He was unable to reduce the oxide, and despite his efforts, did not get to witness this new metal. It was not until 1910 that titanium metal was first isolated by M.A. Hunter. The new metal revealed itself to be a remarkable material, easily worked, incredibly strong and with the ability to retain these properties at high temperatures.

Sources

Titanium metal can be extracted from a few different ores and minerals: rutile, brookite, anatase, ilmenite and titanite. Quantity-wise, Ilmenite is the main ore which is mined for titanium, occuring in sand deposits of Western Australia, Norway, Canada and Ukraine.  The annual world production of titanium metal has varied dramatically from below 100,000mt to several 100,000mt.

The isolation of titanium metal is difficult and was only achieved in the early 20th century by GE in the USA by heating titanium tetrachloride and sodium metal under high pressure in a sealed vessel.  Today titanium metal is extracted by the reduction of titanium ore, either rutile or ilmenite, to create titanium sponge by the Kroll process.  The titanium sponge is then melted to form ingots, which in turn are forged and rolled to create further downstream products.

Uses

Consumption of titanium has remained strong following its popularity in the new industrial phase of the last half of the 20th century.  The boom in the aerospace industry has been the primary driver for this.  Titanium’s main applications are lightweight alloys used to make fan blades for aero-engines, as well as other parts for the aerospace industry, such as fasteners (due to titanium’s strength, and its corrosion resistance and ability to operate at high temperatures).  With the next generation of commercial aircraft (including the Airbus A380 and Boeing 787) there is great potential new demand for titanium metal.

The properties of titanium metal also make it an excellent choice for spectacles, watches, golf clubs and high specification bicycles.  It is also a natural choice for body implants such as bone joints, pins, plates, etc, as it is one of the few metals which the body does not try to reject (being inert, it does not react with the body).

Titanium dioxide production is around 4.3 million mt per year, and its main application is as a substitute to poisonous lead-based white paint. It is used in many substances including plastics, paper, fibres, ceramics, enamels, food colouring, toothpaste, printing inks and laminates.

Titanium’s industrial applications are also a major market sector.  Nearly all acids and hot liquids can be passed through titanium tubes or stored in titanium vessels without the tubes melting or warping making it the perfect material to use in acid factories, desalination plants and so on.  It is thought that if the titanium market becomes more stable and low priced that car makers will consider using it for car bodies which would explode the demand and quantities currently used.

Although a very small proportion of the titanium market, the ferro-titanium market is largely dependent on the outlet of titanium scrap, as well as the workings of the steel industry, due to its application; and thus this market moves with steel production.

Low oxygen in titanium metal is correlated with its strength, and the higher the grade it is.  Grade 4 with 0.40% O2 is the strongest compared to grade 1 with an oxygen content of 0.18%, the softest, as some customers favour strength while others favour malleability.