On 8/16/2019 12:53 PM, Paul Koning via cctalk wrote:

 From what I remember, the detailed analysis involves an "electrochemical 
series", which has metals like sodium at one end, copper closer to the middle, and 
gold at or near the other end.  Metals are compatible if their potential value differs by 
less than a limit.  The limit depends on the environment; in an office you can have a 
larger limit than on a ship where you have salt spray, or a tire factory with lots of SO2 
in the air.

There are also some twists; I think stainless steel is compatible with many things thanks 
to the alloy ("stainless") properties.  In fact, I think the subject came up in 
connection with failure analysis of coin cell battery holders.  The battery cases are 
stainless steel; the question is what contacts are acceptable.  Gold is; there may be 
others but some things that are used in the market are not good choices.


That reminds me, Tubes and More ( https://www.tubesandmore.com ) sell a contact cleaner used for vacuum tubes. That may be useful for cleaning cards and card edge sockets. Deoxit is the product and comes in assorted
types depending what you are cleaning.

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