A hard silvery-grey metal, titanium is found in
nature as a compound within many minerals, but most notably in ilmenite
(FeTiO3) and rutile (TiO2), more commonly found in sand or
soil than hard rock. Other titanium-bearing minerals include perovskite,
titanite, anatase and brookite. Major deposits of titanium minerals are found in
Australia, Canada, India, Norway, South Africa, the Ukraine and the USA.
Titanium is particularly valued for its low density
combined with high strength and excellent corrosion resistance. Pure titanium
can reach an ultimate tensile strength of up to 740 N/sq mm, and an alloy like
LT 33, containing aluminium, vanadium and tin, reaches 1,200 N/sq mm. The
metal's coefficient of thermal expansion is around half that of stainless steel
and copper, and one-third that of aluminium. Its density is around 60% of
steel's, half that of copper's and 1.7 times aluminium's. Its modulus of
elasticity is half that of stainless steel, making it durable and shock
resistant.
The aerospace industry is still the largest single
consumer of the metal. Titanium alloys capable of operating at temperatures from
sub-zero to 600°C are used in aeroengines for discs, blades, shafts and
casings. |