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

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 1800 o C 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, TiO 2

Titanium is not very reactive so we could extract it using carbon Titanium dioxide cannot be extracted from its ore by electrolysis However carbon reacts with titanium making it very brittle Titanium is extracted by displacement from it ore by using a more reactive metal such as sodium or potassium

99% of world’s titanium is produced by the Kroll process: Titanium chloride Titanium dioxide Titanium TiO 2 heated with carbon and chlorine Reaction with molten magnesium displaces titanium Each step costs lots of money

Titanium is the 4 th 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