First 281 words of the document:
Rusting is the special name given to the corrosion of iron and steel. Iron
is relatively abundant and cheap and when made into steel can be made
to have a variety of useful properties. Therefore Iron and steel are the
most widely used metals in the world and rusting is a common problem.
Iron and steel usually rust when exposed to air and water.
What causes Rusting?
There are two main conclusions made:]
Both air and water need to be present for iron to rust
The presence of salt or acid speeds up the rusting of iron
Iron is combined with oxygen. Rust is actually hydrated iron oxide,
formed from the reaction of iron with oxygen and water.
Iron + oxygen + water Hydrated iron oxide (rust)
Tanks left in the desert since the end of the second world war
show hardly any signs of rust because the desert atmosphere
contains little or no water
Ships that have sunk in deep areas of the oceans hardly rust at
all as there is very little air dissolved in the water of the deepest
parts of the ocean
Iron and steel structures built in or near the sea rust very quickly,
this is due to the salt dissolved in the sea water which speeds up
Cars and other iron objects corrode in areas where you get acid
Problems of rusting
The brown flakes of rust which form during the corrosion of iron
and steel are brittle and weak. This causes them to crumble and