Definition - What does Galvanic Corrosion mean?
Galvanic corrosion refers to corrosion damage that occurs when two different metals are in electrical contact in an electrolyte, where the more noble metal is protected and the more active metal tends to corrode.
Corrosionpedia explains Galvanic Corrosion
For galvanic corrosion to occur, three conditions must be present:
- electrochemically dissimilar metals must be present, and
- the metals must be in electrical contact, and
- the metals must be exposed to an electrolyte
The galvanic series in seawater lists the common metals in order from the most anodic to most cathodic (noble). The further apart the metals are in this series, the greater the corrosion difference and speed between the two. For example, zinc will corrode in saltwater extremely quickly when in contact with platinum, but 304 stainless steel in contact with 316 stainless steel will have little effect on each other.
The following are some of the main factors influencing galvanic corrosion rates:
- Potential difference between materials
- Cathode efficiency
- Surface areas of connected materials (area ratio)
- Electrical resistance of the connection between the materials and of the electrolyte