Galvanic Corrosion Can occur due to Oxygen attack or contact of two dissimilar metals in an electrolyte (eg: Copper + Steel). Oxygen Attack (Pitting Corrosion) At the Anode: Metal goes into solution Fe ⟶ Fe 2+ + 2 e - OXIDATION At the Cathode: Oxygen is reduced ½ O 2 + H 2 O + 2 e - ⟶ 2 OH - REDUCTION The variables pH, temperature and the concentration of oxygen affect the rate of corrosion. To avoid this alkaline conditions are maintained in the boiler. Oxygen reacts with iron to give ferric oxide (rust) Fe 2 O 3 which will not protect the metal from further attack and metal is continuously dissolved. 4Fe + 3O 2 → 2 Fe 2 O 3 Hematite (ferric oxide) Oxygen corrosion is usually...
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