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SYSTEM AND MODULE DATA
3.2.7.2 Materials in the cooling circuit
Avoid contact corrosion and pitting
For the screw connections and also for the metallic articles in the cooling circuit which
are in contact with the coolant (electrolyte) a material is to be selected, which forms a
small voltage difference to the heat sink in order to avoid contact corrosion and/or pitting
corrosion (electro-chemical voltage series, see the following table). The specific case of
application must be checked by the customer in tuning of the complete cooling circuit
and must be classified according to the used materials. With hoses and seals take care
that halogen-free materials are used.
A liability for occuring damages by wrongly used materials and from this resulting corro-
sion cannot be taken over!
Material
formed ion
Lithium
Li+
Potassium
K+
Calcium
Ca2+
Sodium
Na+
Magnesium
Mg2+
Titan
Ti2+
Aluminium
Al3+
Manganese
Mn2+
Zinc
Zn2+
Chrome
Cr3+
Iron
Fe2+
Cadmium
Cd2+
Cobald
Co2+
Table 19:
Electrochemical series / standard potentials against hydrogen
Standard poten-
Material
tial
-3.04 V
Nickel
-2.93 V
Tin
-2.87 V
Lead
-2.71 V
Iron
-2.38 V
Hydrogen
-1.75 V
Stainless steel
-1.67 V
Copper
-1.05 V
Carbon
-0.76 V
Silver
-0.71 V
Platinum
-0.44 V
Gold
-0.40 V
Gold
-0.28 V
formed ion
Standard poten-
tial
Ni2+
-0.25 V
Sn2+
-0.14 V
Pb3+
-0.13 V
Fe3+
-0.037 V
2H+
0.00 V
various
0.2...0.4 V
Cu2+
0.34 V
C2+
0.74 V
Ag+
0.80 V
Pt2+
1.20 V
Au3+
1.42 V
Au+
1.69 V
47
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