On Thu, 2009-04-30 at 22:13 -0400, Gary Hoffman wrote:
> Hmmm....I did not know about zinc particles in that particular product. Nor
> did I know that you could form "crystals" of zinc. Perhaps you are just
> referring to small pieces of zinc.
Crystals. Look at a sheet of hot dipped galvanized tin. Lots of crystal
shows there. The crystals are hard enough to break through the thin
aluminum oxide to make good connections.
> But - are not zinc and aluminum far enough apart in the periodic table to
> react with each other ? My chemistry is extremely old and consequently
> vague, but I thought you could even make a battery of those metals (with
> some other components added of course).
Sure you can make a battery, that's why the grease to keep moisture away
> It seems surprising to me to hear this, in any case, and its the first time
> I ever did. Interesting.
Standard technique in the electric wiring trades to keep from having hot
connections with aluminum service entrance cable. Once a wire connection
warms up, the wire would expand more than the lug, so the wire gets
squeezed and then the connection is loose when it cools which makes it
heat faster the next time power is required.
Neither the grease nor the zinc alone works well, but the combination
works quite well. Outdoors more protection like tape or heat shrink
tubing can make the connection last much longer.
> 73 de Gary, AA2IZ
73, Jerry, K0CQ
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