Metals and alloys Flashcards
Why is aluminum used in the manufacture of aircraft?
Because it is strong and has a low density
Why is aluminium used to make food containers?
It is resistant to corrosion
Why is aluminium resistant to corrosion and seemingly unreactive?
It has a protective layer of aluminium oxide on its surface. This prevents the metal beneath from reacting
Why is copper used in electrical wiring?
It is a good conductor of electricity
Why is copper used to make cooking utensils?
It is a good conductor of heat
Uses of mild steel
In car bodies and machinery
Uses of stainless steel
In chemical plants and in cutlery
Uses of zinc
Galvanising and making brass
Alloy
A mixture of two or more elements where at least one of them is a metal
Why are alloys harder than pure metals?
Alloys contain atoms of different sizes, so the regular arrangement of the metal is disrupted. This makes it difficult for layers to slide over each other when a force is applied
Elements in mild steel
Iron and carbon
Elements in brass
Copper and zinc
Elements in stainless steel
Iron, chromium , nickel
Difference between mild steel and pure iron
Mild steel is stronger and harder. It is easily worked and not brittle
What is Brass used for?
Making musical instruments
Why is it useful that brass has a lower melting point than the metals used to make it?
It is easier to cast it into the intricate shapes of the instruments
Why is recycling aluminium beneficial?
It is very expensive to extract aluminium from its ore. Using recycled aluminium saves 95% of the energy needed to make new aluminium
Why is recycling steel beneficial?
It is cheaper to recycle steel than to make it
How does recycling save energy?
Less energy is used in recycling something than in making it from raw materials
How can recycling prevent pollution?
It avoids the need to bury the substances in landfills
Why are many power cables made of copper?
It is a very good electrical conductor- it has a very high electrical conductivity
Why is aluminium used to make overhead power cables?
Aluminium conducts electricity well
Has a low density, preventing sagging.
It is very resistant to corrosion
Why do aluminium cables have a steel core?
It strengthens the cable
