Page 65 - Corrosion Engineering Principles and Practice

46 C h a p t e r 3 C o r r o s i o n E l e c t r o c h e m i s t r y 47

a large surface area ratio is a serious aggravating factor. It is easy to
understand that the effect of a certain amount of anodic current
concentrated on a small area of metal surface will be much greater
than when the effect of the same amount of current is dissipated over

e – e –

Copper

Copper

Steel
(a)

e – e –

Corrosion

Steel
Steel

Copper

(b)
FIGURE 3.8 Galvanic coupling caused by riveting with dissimilar metals:
(a) steel rivets on copper plates, (b) copper rivets on steel plates.