Galvanic corrosion

Galvanic corrosion (also called ‘ dissimilar metal corrosion' or wrongly ‘electrolysis') refers to corrosion damage induced when two dissimilar matter l's are coupled with a corrosive electrolyte. Galvanic corrosion is an electrochemical process In which one metal corrodes onto another when both metals are in electrical co intact, in the presence Of an electrolyte. When a galvanic couple forms, one Of the metals I n the couple becomes the anode and corrodes faster than it would all by itself, while e the other becomes the cathode and corrodes slower than it would by itself.So basically the anode metal is breaking down onto the cathode metal. For galvanic corrosion to occur, three things must be present: Electrochemically dissimilar metals must be pre .NET, these metals must be in electrical contact, and the metals must be exposed to an electrolyte. Galvanic Corrosion was discovered in the late part of the eighteenth century b Lugging Galvanic in a series of experiments wi th the exposed muscles and nerves of a frog that contracted when connected to a conductor.Its humorous to think Galvan ICC corrosion was found on accident when experimenting on frogs. The concept was also e engineered into the useful protection of metallic structures by Sir Humphrey Davys and Mice hall Faraday in the early part of the nineteenth century. The sacrificial corrosion of en metal such as zinc, magnesium or aluminum is a widespread method of protecting metallic Structures. While galvanic corrosion is potentially problematic to civil engineer s, they can use it to their benefit.For example buried or submerged structures, in HTH s case, sacrificial anodes work as part of a galvanic couple, promoting corrosion of the e anode, in order to protect the cathode metal. To dumb it down one metals life is been g drastically reduce so the other metals life will last longer. On another note if you do not want galvanic corrosion taking place corrosion inhibitors such as sodium nitrite or sodium moldboard can be injected into the systems to reduce the galvanic potential.However, the application Of these co erosion inhibitors must be monitored closely. If the application of corrosion inhibitors increases the conductivity of the water within the system, the galvanic corrosion potent al can be greatly increased. A different means of avoiding galvanic corrosion is to coins deer the 2 electrical potential of the metals you are selecting. A galvanic series list the el citric potentials of metals, the relative position of two metals on such a series gives good indication of which metal is more likely to corrode more quickly.Looking back at my opening statement, you can now understand why galvanic corrosion can be so hostile. If you select the wrong metals in a system, and the e load bearing metal of the system corrodes, you systems is bound to fail. On the to her end of the spectrum, galvanic corrosion can possibly be helpful, if indeed you want t o sacrifice one metal in order to protect another. With an indented knowledge of galvanic corrosion civil engineers can predict and act upon potentially hazardous situations. 3