reducing corrosion

Question 1

what are the 4 methods to reduce rusting/corrosion?

Answer 1

painting
coating with oil, grease or plastic
plating with zinc (galvanising)
plating with tin

Question 2

what happens if the paint is damaged

Answer 2

rusting starts on the exposed metal. It continues underneath the pain until it flakes off, exposing fresh metal to air and water. Oil, grease and plastic have similar problems

Question 3

what is sacrificial protection?

Answer 3

involves a more reactive metal. As long as the iron or steel object is in contact with it, the more reactive metal corrodes first. Used by ships

Question 4

how does metal plating work?

Answer 4

a layer of metal plated onto an iron or steel metal objet prevents air and water reaching the iron or steel below.

Question 5

how does galvanising work

Answer 5

first you dip the metal into molten zinc, the zinc does two things

• stops air and water from entering the iron or steel below
• acts as sacrificial protection as it is more reactive than iron meaning that the iron will be protected even if the zinc gets damaged or destroyed.

Question 6

how does tin plating work

Answer 6

involves electroplating tin onto the steel object. However tin is less reactive than iron so if the plating gets damaged, it will rust even faster than normal