[Lowfer] Need recommendation for anti-corrosion bonding for dissimilar metals

[William E. Isakson]

Andy, Somettimes Army Truck mechanics put a coat of grease on battery
terminals to suppress that corrosion, but it leaves an insulating black
crud in the connections after a while.   The best I know to do is to pour
some backing soda water solution on the white stuff and clean the
connection.   It foans and you wash it off with plain water.  the you put
the light coat of grease.   It is quick to do, but won;t stop it from
happening.
As a metals chemist I would just tell you that there is an electron
gradient at such a terminal and it will corrode.  You can minimize it by
putting an insulator between the metals, but that does not solve your
problem as there would be no connection.
The point is with connections between dissimilar metals, there is a voltage
at the connection balanced by an electron trade that leaves metal ions
present.  If you get rid of those ions in whatever way, the voltage
difference will make more ions.   The trick is to isolate the ions from the
wet oxygen atmosphere so that they do not make oxides or other salts.  That
is why the grease works.   Put a thin coat, but know that eventually you
are going to have to clean it, but not so soon as without the grease.  Do
not put the grease in the connection, but on the connection so that it
seals from the air.   The grease dries out, so you have to put it on again
in six months or so.  Or earlier if the rain erodes the grease off.
Bill
--------


Bill Isakson     AC6QV
Roseburg, Oregon USA
bill.isakson at gmail.com




On Tue, Sep 25, 2018 at 5:30 PM Andy - KU4XR via Lowfer <
lowfer at mailman.qth.net> wrote:

> Hi all:
>
> What can be used ( and purchased at home repair store, etc ) to hold off
> corrosion when bonding galvanized,
> aluminum, or stainless steel to copper ?? ( my ground rod specifically )
> .. The white - powdery corrosion sets in
> very quickly.. Thanks for suggestions:
>
> 73:
>
> Andy - KU4XR
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