Galvanic Corrosion Occurrence and Prevention

Galvanic Corrosion Occurrences and Prevention refers to the process of preventing metal or alloy affected by corrosion. 

Galvanic Corrosion is an electrochemical process which refers to corrosion damage occurs when two dissimilar materials are integrated into a corrosive electrolyte. Galvanic Corrosion occurs when a metal or alloy is electrically coupled to a different metal or alloy. Dissimilar metals and alloys have different electrode potentials. When a galvanic couple form or more than one metals come into contact with an electrolyte, one metal acts as an anode and the other as a cathode.
The pair of the anode (Negative terminals) and cathode (Positive terminals) creates a galvanic cell.

Galvanic Corrosion Occurrence and Prevention
Identifying Galvanic Corrosion:
  • Scratches in a metal surface
  • A leak on an aluminum-hulled vessels
  • Blistered or peeling paintwork
  • Corrosion occurs in corrugated iron
  • Differential stresses in a metal
  • Difference in temperature
  • Conductive deposits
Galvanic Corrosion generally occurred on Al-Cu Metal Bond pad corrosion during water saw resulting in pitting.
Main factors influencing galvanic corrosion rates:
  • The potential difference between materials.
  • Cathode efficiency and the potential difference
  • The Ratio of the cathodic and anodic region and Deposition of Impurities
  • An electrical resistance of the connection between the materials and of the electrolyte
  • pH of the medium, Temperature, and Effect of oxygen.
  • Presence of passive film.
  • Hydrogen overvoltage.