Compatibility of distinct materials

My question relates to the Compatibility of distinct materials when used in assembly. To be specific, there is a case where a SS tube is joined to a Copper tube wit a brass coupling. At the joint, corrosion has set in. Why and what is the cause? What metal properties of these materials are conflicting causing corrosion.? What is actually a Galvanic corrosion?
Thanks. I hope to get good and informative response. Received on Fri May 30 03:15:00 2003