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Anodic protection (AP) otherwise referred to as Anodic Control is a technique to control the corrosion of a metal surface by making it the anode of an electrochemical cell and controlling the electrode potential in a zone where the metal is passive.
A galvanic anode, or sacrificial anode, is the main component of a galvanic cathodic protection system used to protect buried or submerged metal structures from corrosion. They are made from a metal alloy with a more "active" voltage (more negative reduction potential / more positive oxidation potential ) than the metal of the structure.
Aluminum sacrificial anodes (light colored rectangular bars) mounted on a steel jacket structure. Zinc sacrificial anode (rounded object) screwed to the underside of the hull of a small boat. Cathodic protection (CP; / k æ ˈ θ ɒ d ɪ k / ⓘ) is a technique used to control the corrosion of a metal surface by making it the cathode of an ...
The unshaded bars indicate the location on the chart of those steels when in acidic/stagnant water ( like in the bilge ), where crevice-corrosion happens. Notice how the *same* steel has much different galvanic-series location, depending on the electrolyte it's in, making prevention of corrosion .. more difficult.
A sacrificial metal is a metal used as a sacrificial anode in cathodic protection that corrodes to prevent a primary metal from corrosion or rusting. [1] It may also be used for galvanization. Equation
Corrosion prevention measures, including Cathodic protection, designing to prevent corrosion and coating of structures fall within the regime of corrosion engineering. However, corrosion science and engineering go hand-in-hand and they cannot be separated: it is a permanent marriage to produce new and better methods of protection from time to time.
Certain metals, such as zinc, may become embrittled from the hydrogen gas which is evolved at the cathode. The anodic process avoids this effect since oxygen is being generated at the anode. The major advantages that are normally touted for the cathodic processes are: Higher levels of corrosion protection are possible.
Galvanized steel can last for many decades if other supplementary measures are maintained, such as paint coatings and additional sacrificial anodes. Corrosion in non-salty environments is caused mainly by levels of sulfur dioxide in the air.