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Galvanic CorrosionTechnically, corrosion is the attack and progressive destructions of a metal by means of a chemical action. Galvanic corrosion, which is characterized by its destructive power, comes from an electrolysis phenomenon between two metals of different electrical potential that is in contact and in the presence of humidity. Between the metallic parts of the boat that have contact with water like the propeller, rudder, cooling systems and some connections, can be a current flow, and therefore a corrosion of metallic pieces, even if the metals are physically connected (like the rudder and its ironworks, the propeller, the axis and the motor, etc.), or not. Certain metals, “Common” called, are corroded faster than the ones known as “Noble” metals. To the right, there is a list of the most used metals in facilities and marine equipment, in an order from minor to greater degree of galvanic corrosion that they can get to suffer, both in marine water and at room temperature.
It is necessary to avoid alloys that contain common metals like brass for example, which lasts very little under the water. The most effective method to resist the galvanic corrosion is protecting all the submerged equipment or machinery with pure zinc, joining it to the metal to protect or connecting it with a metallic band.
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Propeller Pages -
78-80 North Street, PO Box 3030 Pallas St. Post Office,
Maryborough Qld. 4650, Australia. Phone: + 61 7 41 231085 Fax: +61 7 4123 3590 E-mail: propellerpages@olds.com.au |