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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 electrochemical cell. [1] A simple method of protection connects the metal to be protected to a more easily corroded "sacrificial metal" to act as the anode. The sacrificial metal then corrodes ...
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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.
Cathodic protection uses one or more sacrificial anodes made of a metal which is more active than the protected metal. Alloys of metals commonly used for sacrificial anodes include zinc, magnesium, and aluminium. This approach is commonplace in water heaters and many buried or immersed metallic structures.
The terms anode and cathode are not defined by the voltage polarity of electrodes, but are usually defined by the direction of current through the electrode. An anode usually is the electrode of a device through which conventional current (positive charge) flows into the device from an external circuit, while a cathode usually is the electrode through which conventional current flows out of ...
Anodic protection is used for carbon steel storage tanks containing extreme pH environments including concentrated sulfuric acid and 50 percent caustic soda where cathodic protection is not suitable due to very high current requirements. In anodic protection potentiostat is used to maintain a metal at constant potential with respect to ...
The galvanic series (or electropotential series) determines the nobility of metals and semi-metals.When two metals are submerged in an electrolyte, while also electrically connected by some external conductor, the less noble (base) will experience galvanic corrosion.
The corrosion protection is primarily due to the anodic potential dissolution of zinc versus iron. Zinc acts as a sacrificial anode for protecting iron (steel). While steel is close to -400 mV, depending on alloy composition, electroplated zinc is much more anodic with -980 mV. Steel is preserved from corrosion by cathodic protection. Alloying ...