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Galvanic Corrosion Experiments

Galvanic corrosion (also called ' dissimilar metal corrosion' or wrongly 'electrolysis') refers to corrosion damage induced when two dissimilar materials are coupled in a corrosive electrolyte. When a galvanic couple forms, one of the metals in the couple becomes the anode and corrodes faster than it would all by itself, while the other becomes the cathode and corrodes slower than it would alone.

  • corrosion of the anode will accelerate

  • corrosion of the cathode will decelerate or even stop

One classic experiment to illustrate that particularly powerful form of corrosion consists in using rivets of dissimilar metals apart in the galvanic series. The idea is to use the rivets on a plate of the opposite metal and immerged the assembled pieces into water. The same concept was engineered in a way to reveal the efficiency of corrosion preventive compounds. The steel-copper couple in this second experiment was created by using a brass bolt to hold a steel washer on a piece of wood floating on water to provide humidity.