Cathodic Disbondment And Galvanic Corrosion; Figure 9. Cathodic Protection And Anodes; Figure 10. Galvanic Corrosion - Teledyne WORKHORSE Operation Manual

WorkHorse H-ADCP Operation Manual

Cathodic Disbondment and Galvanic Corrosion

Cathodic disbondment is the loss of adhesion between a cathodic coating and its metal substrate due to
the corrosion reaction that take place in the interface of coatings. Disbondment of coating occurs when
coatings in a cathodic protection system interact either chemically or physically, ultimately causing corro-
sion beneath the coat.
Cathodic Protection is a technique used to control the corrosion of a metal surface by making it the cath-
ode of an electrochemical cell. A simple method of cathodic protection connects the H-ADCP's metal
housing to a more easily corroded "sacrificial metal" anode. The sacrificial metal then corrodes instead of
the protected metal.
The anode only provides cathodic protection as long as it is present and connected to the
H-ADCP housing;
Dissimilar metals and alloys have different electrode potentials, and when two or more come into contact
in an electrolyte, one metal acts as anode and the other as cathode. The electro-potential difference be-
tween the dissimilar metals is the driving force for an accelerated attack on the anode member of the gal-
vanic couple.
Galvanic corrosion will contribute to accelerated corrosion of parts of the H-ADCP system.
When mounting the H-ADCP aluminum housing to other metals, always use isolation
washers.
check the anode condition
Figure 9. Cathodic Protection and Anodes
Figure 10. Galvanic Corrosion
EAR-Controlled Technology Subject to Restrictions Contained on the Cover Page.
on a regular basis.
May 2015
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