OOp. Wouter says "Alu oxide is conducting".
Nope. Wrong.

I worked for Anaconda Wire and Cable Co in their research lab making and testing anodized coatings for their good insulating properties.

Now--If you bust thru this thin tough coating, there is raw metal that corrodes yada, yada...
> hence galvaic corrosion will progress much like it would with a non-anodised element.