Jake is right, I work for an airline and what is causing the corrosion is the different metals that come in contact with each other. At work when we put two different metals together we use a sealant between them. When you use the ss rivets dip them in some rtv silicone to help prevent the contact between the metals. Water acts as the electrolyte to cause the corrosion. The less water touches the metal the less corrosion.

airborne