Titanium is a strong, lightweight metal that occurs in several minerals and is not especially rare. It went unsuspected, however, until it was identified as an unknown oxide around 1790 by English geologist William Gregor and confirmed by German chemist Martin Heinrich Claproth.
Titanium the metal is extremely difficult to extract from its oxide. This was first achieved in 1910. After World War II, William Justin Kroll developed a commercially viable process involving titanium tetrachloride. Until then, titanium had been at best a laboratory curiosity. It became a space-age wonder metal.
Mining and Production
Titanium is the ninth-most common element in the Earth's crust. It occurs in many minerals, but only two are economical ores (ilmenite and rutile). China and Australia are the leading producers. Titanium is generally surface mined.
Titanium refining by the Kroll process works commercially, but not so much as the refining of other metals. It consumes costly magnesium. The more recent Hunter process uses sodium, a minimal improvement. Thus, titanium remains expensive because of the production cost.
Most titanium ore (over 95%) is actually not reduced to the pure metal, but turned into titanium dioxide (TiO2), a much easier task.
Properties and Uses
Titanium dioxide, the main use for titanium, is a bright white powder. Millions of tonnes per year are used as a paint base, in plastic, toothpaste, and paper where brilliant white is called for. TiO2 also absorbs ultraviolet light and so is used in sunscreen. Yes, the space-age metal is most commonly used in the most basic consumer goods.
Titanium the metal is lightweight and strong. It has the highest strength per weight of all common metals, 60% heavier than aluminum but more than twice as strong. It has a high melting point. Titanium is ductile and, as usually manufactured, has a high tensile strength similar to steel. It is very corrosion-resistant.
Titanium is not as hard as steel, so will survive less wear and scratching. It is difficult to machine and very difficult to weld. Like aluminum and magnesium, it will burn if heated to high enough temperature (600°C).
Titanium is used where light weight is critical and cost is not, such as aerospace vehicles – missiles, aircraft engines, airplane frames. The Russian Alfa-class submarine had an innovative titanium hull that reduced vibration noise. The SR-71 "Blackbird" reconnaissance jet (below) also had an early titanium hull (titanium from the Soviet Union).
Titanium is a vanity metal for watch cases and laptop computers. It is also found in costly backpacks, tennis rackets, racing bikes, and other sports equipment where strength must be balanced against weight. Because it resists sea water corrosion, titanium is used in propeller shafts, desalination plants, aquariums, and marine instrumentation.