F22 Raptor – fastest aircraft in the world – it’s true top speed is unknown

What is the link between……

this:

… 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

• It’s strength, light weight and resistance to corrosion make titanium alloy a good material to use in biomedical components e.g. hip replacements

Uses of titanium:

It’s resistance to corrosion means titanium alloy is used to make:

• structural components in chemical plants

• ship parts that would be exposed to seawater, e.g. hulls and propeller shafts

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 chloride

Titanium dioxide

Titanium

TiO2 heated with carbon and chlorine

Reaction with molten magnesium displaces titanium

• Titanium is the 4th most abundant metal on Earth, after aluminium, iron and magnesium but it is VERY EXPENSIVE

Why don’t we use titanium more often if it is so useful?

• 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