Richard -
I have plans to try additional reference texts on a visit to
the local university library, hopefully later this week.
I started out searching for a good lookup table. Then in
the research I've done so far, I discovered many of the
permutations involved in test methods to determine an
electrochemical potential. There's a lot to know.
I did a search on a mil-spec web delivery system and found
only a couple of documents (MIL-STD-889A, Dissimilar Metals;
MIL-HDBK-1857, Grounding, Bonding and Shielding Design
Practices) that were only moderately useful. 889A is more
of a test specification and 1857 is a bit far out of the
scope I'm looking for. No look up tables for specific
alloys, though; only for base metals and generically
referenced alloys.
I did find a large number of web sites devoted to corrosion
and similar topics, some with value ranges for the materials
I'm reviewing and additional information from material
vendors.
As examples of where data out there begins to diverge from
Table J.1 are related to the variety of standard alloys
available that within a "family" can have significant
differences in half-cell potential from one another. For
instance, aluminum alloys and austenitic stainless steels.
Other questions arise (among others):
just how much Mg needs to be alloyed with Al to fit into
the "Al/Mg" category, since standard alloys vary from 0.4%
to over 5% Mg?
certain austenitic stainless steels have more than 0.1 V
separation from the end points of others
This is an interesting exercise; both a refresher on
materials and chemistry, and a valuable learning experience.
'Welcome back my friends to the show that never ends...'
Regards,
Peter L. Tarver, PE
Product Safety Manager
Homologation Services
Sanmina-SCI Corp.
San Jose, CA
[email protected]
> From: [email protected] [mailto:[email protected]]
> Sent: Tuesday, October 14, 2003 3:43 PM
>
> Peter,
>
> I understand that the origins were a US MIL spec.
> Although I have not checked, I seem to recall
> that pretty much the same information was also
> contained in IEC 380. We are therefore going
> way, way, back in the annals of time.
>
> Have you tried looking up the electro-potentials
> in a book of chemical constants, I seem to recall
> using such sources to find information not in
> Annex J a while (and I mean A WHILE!) back.
>
> Cheers,
>
> Richard Hughes
> Safety Answers Limited
>
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