Unit 9 - oxidation and corrosion

Question 1

characteristics of mild steel

Answer 1

excellent structural material as it is cheap easily formed and mechanically strong.
it rust at low temperature and oxidises at high temperatures.
FeO forms but it is not very protective

Question 2

How to prevent corrosion

Answer 2

thicker material to allow for it
paints and coatings
corrosion inhibitors
cathodic protection

Question 3

Explain Galvanic corrosion

Answer 3

it occurs when a potential difference is established between two electrically connected metals immersed in a corrosive or conductive solution

Question 4

Prevention of galvanic corrosion

Answer 4

select metal alloys as close together as possible in the galvanic series
avoid unfavourable area effect of a small anode and large cathode
insulate dissimilar metals
apply coatings with caution
avoid threaded joints for materials far apart in the galvanic series

Question 5

what is pitting

Answer 5

localised attack of a boldly exposed metallic surface where the rate of attack is greater in small areas than at others