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(L. titans, the first sons of the Earth, mythology)
Discovered by Gregor in 1791; named by Klaproth in 1795. Impure titanium was prepared
by Nilson and Pettersson in 1887; however, the pure metal (99.9%) was not made until 1910
by Hunter by heating TiCl4
with sodium in a steel bomb.
Titanium is present in meteorites and in the sun. Rocks obtained during the Apollo 17
lunar mission showed presence of 12.1% TiO2 and rocks obtained during earlier Apollo
missions show lower percentages.
Titanium oxide bands are prominent in the spectra of M-type stars. The element is the
ninth most abundant in the crust of the earth. Titanium is almost always present in
igneous rocks and in the sediments derived from them.
It occurs in the minerals rutile, ilmenite, and sphene, and is present in titanates and
in many iron ores. Titanium is present in the ash of coal, in plants, and in the human
The metal was a laboratory curiosity until Kroll, in 1946, showed that titanium could
be produced commercially by reducing titanium tetrachloride with magnesium. This method is largely used for producing
the metal today. The metal can be purified by decomposing the iodide.
Titanium, when pure, is a lustrous, white metal. It has a low density, good strength,
is easily fabricated, and has excellent corrosion resistance. It is ductile only when it
is free of oxygen. The metal, which burns in air,
is the only element that burns in nitrogen.
Titanium is resistant to dilute sulfuric and hydrochloric acid, most organic acids,
most chlorine gas, and chloride solutions.
Natural titanium is reported to become very radioactive after bombardment with
deuterons. The emitted radiations are mostly positrons and hard gamma rays. The metal is
dimorphic. The hexagonal alpha form changes to the cubic beta form very slowly at about
880oC. The metal combines
with oxygen at red heat, and with chlorine at 550oC.
Titanium metal is considered to be physiologically inert. When pure, titanium dioxide
is relatively clear and has an extremely high index of refraction with an optical
dispersion higher than diamond.
Natural titanium consists of five isotopes with atomic masses from 46 to 50. All are
stable. Eight other unstable isotopes are known.
Titanium is important as an alloying agent with aluminum,
iron, and other metals. Alloys of titanium are
principally used for aircraft and missiles where lightweight strength and ability to
withstand extremes of temperature are important.
Titanium is as strong as steel, but 45% lighter. It is 60% heavier than aluminum, but
twice as strong.
Titanium has potential use in desalination plants for converting sea water into fresh
water. The metal has excellent resistance to sea water and is used for propeller shafts,
rigging, and other parts of ships exposed to salt water. A titanium anode coated with
platinum has been used to provide cathodic protection from corrosion by salt water.
It is produced artificially for use as a gemstone, but it is relatively soft. Star
sapphires and rubies exhibit their asterism as a result of the presence of TiO2.
Titanium dioxide is extensively used for both house paint and artist's paint, because
it is permanent and has good covering power. Titanium oxide pigment accounts for the
largest use of the element. Titanium paint is an excellent reflector of infrared, and is
extensively used in solar observatories where heat causes poor seeing conditions.
Titanium tetrachloride is used to iridize glass. This compound fumes strongly in air
and has been used to produce smoke screens.
The price of titanium metal powder (99.95%) is about $100/lb.
Sources: CRC Handbook of Chemistry
and Physics and the American Chemical Society.