Corrosion Flashcards
when does corrosion happen
when a metal continues to oxidise so the metal becomes weaker over time
what is rusting
the corrosion of iron and steel
when does iron rust
when it reacts with BOTH oxygen and water
how do you remove oxygen from water
boil the water
how do you remove water vapour from the air
using anhydrous calcium chloride
how can rusting of iron be prevented
exclusion of oxygen
exclusion of water
sacrificial protection
what are the different ways of preventing rusting
coat with paint / coat with oil
galvanising
sacrificial protection
electroplating
tin plating
what is sacrificial protection
blocks of more reactive metal than iron such as magnesium or zinc are attached to the iron or steel objects. Magnesium and zinc lose electrons more easily than iron, so oxidise more easily than iron
what is sacrificial protection used for
to prevent steel hulls of ships and steel piers from rusting
why can aluminium not be used as a sacrificial metal
aluminium has a thin layer of aluminium oxide on its surface. This oxide layer adheres to the metal and stops any further reaction therefore aluminium does not corrode
