Titanium is being increasingly used in our modern society. It is light, strong and corrosion-resistant. These properties allow it to be used in the aerospace industry, building industry, sports goods industry and as implants in a number of surgical procedures.
Uses of titanium
Titanium is as strong as steel but 45% lighter. It is corrosion-resistant due to the presence of a thin oxide coating on the surface of the metal.
Due to excellent resistance to seawater, it is used in offshore rigs, ships’ propellers and rigging, and desalination plants. Because titanium is lightweight, stable, heat-resistant and easy to work with, it also finds many uses in aviation and aerospace applications.
The human body does not reject titanium, so it can be used for joint replacement and tooth implants. These are normally alloys of titanium with 6% aluminium and 4% vanadium. Titanium alloys are also used in eyeglass frames.
Architectural applications of titanium exist. The Guggenheim Museum in Bilbao, Spain, is sheathed in 33,000 square metres of pure titanium sheet.
Apple computers recently put a titanium laptop computer on the market for its light weight.
Traditionally reserved for industrial uses, titanium has only recently been included as a jewellery material and is increasingly popular. Unlike gold and silver, which are traditionally melted and moulded, titanium requires that rings be forged out of a solid block of metal. Titanium rings cannot be resized. Most of the cost in making a titanium ring is in the skilled labour to create a ring from such a hard metal.
While generally considered costly, titanium bicycle frames are widely considered to be the most durable. Compared to a steel frame, a titanium bicycle frame of the same dimensions would have a ‘whippy’ feel because it would be less stiff. This might be more noticeable in a bicycle carrying a heavy load. However, titanium frames are made with larger diameter tubes in order to compensate for this effect.
Traditionally, sports rackets have been made of wood, steel, aluminium and graphite. Titanium is the most recent development. Harder and heavier than graphite fibres, titanium is not used in solid pieces in the rackets. Instead, it is used in the form of a mesh positioned at critical points in the racket frame. This improves both resistance and stability during use and dampens twisting forces on impact.
Titanium dioxide
Titanium dioxide is by far the most important of the compounds of titanium and accounts for the largest use of the metal. Around 5 million tonnes are produced per year. It is a brilliant white, non-toxic pigment that has many uses, including white paints, sunscreens, infrared reflectors, wedding cake icing and self-cleaning glass.
Sapphires and rubies are mainly composed of alumina (aluminium oxide). If there is a trace of titanium dioxide (rutile) present as ‘an inclusion’, this can give these gemstones their ‘ star’ quality.
Production
Titanium is not found in its native state but mostly as its oxide. Ilmenite is a complex oxide of iron and titanium (FeTiO3), and rutile is mainly titanium dioxide (TiO2).
The commercial extraction process – the Kroll Process – involves treatment of the ore with chlorine gas to produce titanium tetrachloride. This is then purified and reduced to a metallic titanium sponge by reaction with magnesium or sodium.
| TiO2(s) + 2Cl2(g) + C(s) | → | TiCl4(l) + CO2(g) |
| TiCl4(l) + 2Mg(s) | → | Ti(s) + 2MgCl2(s) |
The titanium sponge then undergoes an alloying and melting process.
The process is a costly one, since it involves labour-intensive procedures. World production of the metal is about 100,000 tonnes per year.
Nature of science
Science is a blend of logic and imagination. One of the habits of mind of scientists is that of open mindedness where new ideas are given consideration.
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Watch this video to find out about New Zealand company, Titanium Technologies New Zealand (TiTeNZ), it is aiming to create a world-class, New Zealand-based platform in titanium powder metallurgy.
