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GALVANIC
TABLE
Galvanic
compatibility table.
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Compatibility of dissimilar metals
may be predicted by consideration of their "Anodic Index"
The compatibility of two different
metals may be predicted by consideration of their "Anodic
Index". This parameter is a measure of the electrochemical
voltage that will be developed between the metal and gold. To find
the relative voltage of a pair of metals it is only required to
subtract their Anodic Indexes.
For normal environments, such as
storage in warehouses or non-temperature and humidity controlled
environments, there should not be more than 0.25 V difference in the
"Anodic Index". For controlled environments, in which
temperature and humidity are controlled, 0.50 V can be tolerated.
For harsh environments, such as outdoors, high humidity, and salt
environments, there should be not more than 0.15 V difference in the
"Anodic Index". For example; gold/silver would have a
difference of 0.15V being acceptable.
Often when design requires that
dissimilar metals come in contact, the galvanic compatibility is
managed by finishes and plating. The finishing and plating selected
allows the dissimilar materials to be in contact, while protecting
the base materials from corrosion.
|
Metal
|
Index
(V)
|
|
Most Cathodic
|
|
Gold,
solid and plated, Gold-platinum alloy
|
-0.00
|
|
Rhodium
plated on silver-plated copper
|
-0.05
|
|
Silver,
solid or plated; monel metal. High nickel-copper alloys
|
-0.15
|
|
Nickel,
solid or plated, titanium an s alloys, Monel
|
-0.30
|
|
Copper,
solid or plated; low brasses or bronzes; silver solder; German
silvery high copper-nickel alloys; nickel-chromium alloys
|
-0.35
|
|
Brass
and bronzes
|
-0.40
|
|
High
brasses and bronzes
|
-0.45
|
|
18%
chromium type corrosion-resistant steels
|
-0.50
|
|
Chromium
plated; tin plated; 12% chromium type corrosion-resistant
steels
|
-0.60
|
|
Tin-plate;
tin-lead solder
|
-0.65
|
|
Lead,
solid or plated; high lead alloys
|
-0.70
|
|
2000
series wrought aluminium
|
-0.75
|
|
Iron,
wrought, gray or malleable, plain carbon and low alloy steels
|
-0.85
|
|
Aluminium,
wrought alloys other than 2000 series aluminium, cast alloys of
the silicon type
|
-0.90
|
|
Aluminium,
cast alloys other than silicon type, cadmium, plated and
chromate
|
-0.95
|
|
Hot-dip-zinc
plate; galvanized steel
|
-1.20
|
|
Zinc,
wrought; zinc-base die-casting alloys; zinc plated
|
-1.25
|
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Magnesium
& magnesium-base alloys, cast or wrought
|
-1.75
|
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Beryllium
|
-1.85
|
|
Most
Anodic
|
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For
more information on Galvanic corrosion - See:
http://en.wikipedia.org/wiki/Galvanic_corrosion
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last revised 05 May, 2025
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