4.10 - Uses of Metals

Why a metal suits its job

• A metal is picked for a job because of its properties.
• While all metals conduct heat and electricity and have relatively high strength, they differ in density, conductivity, hardness, and reactivity.

Aluminium - Low density

Aluminium has a low density (light for its size):

• Aircraft and bicycle frames - Low density keeps the mass down.
• Overhead electrical cables - Low density combined with good electrical conductivity allows cables to hang between pylons without breaking under their own weight.
• Food containers and drinks cans - Resists corrosion, so it doesn't react with food or drinks.

Copper - Conductor and ductile

Copper is a very good conductor of heat and electricity, and it's ductile (can be drawn into a wire without snapping):

• Electrical wiring - Good conductivity carries the current efficiently, and ductility allows it to be drawn into thin wires.
• Water pipes and tanks - Malleable enough to bend, hard enough to hold its shape, unreactive with water, and has high thermal conductivity.

Iron and steel - Cheap and strong

Chosen where high strength is needed and weight isn't a problem:

• Wrought iron is almost pure iron. It's malleable, making it easy to shape for gates and railings.
• Steel is harder and stronger than iron, used for bridges, girders, building frames, machinery, engine parts, tools, and car bodies.
• Drawback: iron rusts readily in damp air.