I am currently studying the effect of metal coating to steel. I want to test the galvanic current between steel and aluminum by getting the current that passes through a wire that connects them in an electrolyte solution, to know if the specific aluminum will fit as a good coating for the steel. What should I use as the couple material for the steel? Should it be the coated steel or the metal to be coated? I'm using ASTM G71 as the reference method.
Wikipedia states:"Galvanic corrosion (also called bimetallic corrosion) is an electrochemical process in which one metal corrodes preferentially when it is in electrical contact with another, in the presence of an electrolyte." What are the two metals? How would we know??!! The general answer is:"They are the two metals which form the galvanic cell (in contact with the electrolyte)." Depending on your exact circumstances, this might be the metallic coating and the base metal, or it could be the metallic coating and the metallic coating,or even some other metal component in electrical contact. Of course, if the metallic coating is perfectly homogeneous and completely encloses the base metal, then there will be no galvanic corrosion (at least, not until other corrosion mechanisms have changed that situation).