> I haven't heard of magnesium being used for the purpose, but zinc anodes are
> common practice in the boating community. I, too, have always wondered if
> that would be a useful application in cars.
>
> "Ole" Olson
Yep, I've heard of this, too. As Tom correctly points out when two
dis-similar metals are in a conductive solution, a battery is created.
And if I recall, one metal loses ions and the other gains, depending
where they are relative to each other in some chemical reaction table.
I think we need a chemist's input here, but I suspect zinc wouldn't be
appropriate in this case. My chemistry is many decades old so I'm very
fuzzy on this stuff, but I believe zinc is in between copper and
aluminum in this whatever-the-heck-it's-called table (valence, emf
diff?). And if I recall, what is needed is something with a larger
difference to redirect this reaction. I know from experience that
when the reaction is between iron and copper, iron is the one that
corrodes and with copper and aluminum, aluminum takes the hit.
Of course with salt water, this reaction is very fast because sodium
(and other sea water salt ions) are such good conductors. But I thought
that aluminum was generally avoided in salt water applications because
of this strong reaction. My guess is that in marine engines it's the
copper to iron reaction that the zinc is used to counter. But then I
know diddly squat about marine engines.
Roland
|