What is the link between……
this:
F22 Raptor – fastest aircraft in the world
– it’s true top speed is unknown
… and this?
artificial hip
replacements
Both the Raptor and hip replacement
joints are made from the metal
Titanium
Titanium is a transition metal – where in
the Periodic Table would you find it?
Titanium
Properties of titanium:
• VERY STRONG – as strong as steel but
45% lighter
• RESISTS CORROSION – more resistant
to acids and alkalis than aluminium, iron
and magnesium
• LOW DENSITY – so LIGHT and EASY
TO SHAPE
• VERY HIGH MELTING POINT 1800oC
• CAN WITHSTAND EXTREMES OF
TEMPERATURE when ALLOYED with
aluminium and vanadium
Uses of titanium:
• It’s strength, light
weight and resistance to
corrosion make titanium
alloy a good material to
use in biomedical
components e.g. hip
replacements
It’s resistance to corrosion means titanium
alloy is used to make:
• ship parts that would be
exposed to seawater,
e.g. hulls and propeller
shafts
• structural components in
chemical plants
Because of its strength combined with light
weight, titanium alloy is also used to make:
military armour
plated vehicles
Aircraft e.g. the Raptor
Titanium alloy can withstand very
high temperatures so it is
commonly used in structural
components in:
• aircraft
• satellites
• spacecraft
Extraction of titanium:
• Titanium is not found as an
element – it is extracted
from its ore rutile in the
Kroll process
• In rutile, titanium is found
as titanium dioxide, TiO2
• Because titanium is more reactive than
carbon, it cannot be extracted in a blast
furnace using carbon
• Titanium dioxide is covalently bonded
so cannot be extracted from its ore by
electrolysis
• 99% of world’s titanium is produced by
the Kroll process:
Titanium
dioxide
Titanium
chloride
TiO2 heated
with carbon
and chlorine
Titanium
Reaction with
molten magnesium
displaces titanium
Why don’t we use titanium more
often if it is so useful?
• Titanium is the 4th most
abundant metal on Earth, after
aluminium, iron and magnesium
but it is VERY EXPENSIVE
• Pure titanium costs £8,000 per tonne
• Titanium alloy costs £20,000 - £30,000
per tonne
• Compared to aluminium and steel alloys
which cost £1,000 - £2,000 per tonne
• Cleaner, quicker and cheaper method, the
Fray process, now developed in which
electrolysis is used to ‘suck out’ the
oxygen from titanium dioxide, leaving a
porous sponge of titanium metal
• Metals other than titanium now being
extracted by this process
• Process also allows alloys to be produced
directly from mixtures of oxides e.g.
mixture of TiO2 and Nb2O5 gives
superconducting alloy NbTi