Dick Pierce wrote:
Audio Empire wrote:
The radio shack speaker cable was standard copper AFAICS,
Copper doesn't rust, but it does corrode
Actually, to be precise, the chemical process that causes
iron to rust is the same that causes copper to turn green:
the rersult is, in both cases, an oxide of the metal that's
formed the same way.
To be precise, copper oxide (copper(II) oxide to be even more precise) is black.
That green stuff is a result of further reactions, mostly with carbon, chlorine,
and sulfur compounds.
Both are covered under the broad
blanket of "corrosion," of which oxidization by atmospheric
oxygen is but one type. Yes, copper doesn't "rust" because
the oxides of sopper doen't look the same as the oxides of
iron ("rust" being derived from one or another word for
"red").
But, it's not that iron "rusts" and copper "corrodes" as
distinctly different processes: they're the same process
but with different names.
The similar (not same, as copper is not iron) process just makes copper black.
Then we have the case of wire turning green inside an
insulating jacket: it's still the same oxidization
reaction, but one that is, ahem, encouraged by a less-
that-ideal choice of plasticizers in the insulation.
Thats true that poorly chosen isolation causes sometimes quick deterioration of
the wire covered by it, but it's other elemnts than oxygen which make copper
green. There is of carbon and ofteh chlorine as well to make wires green.
Generally, plasticizers (the chemical that make plastic [n]
plastic [adj]) are pretty nasty. Dioctyl pthalate is one
that springs to mind and, hopefully springs right out again
quickly. A lot of these things are either sufficiently
volatile (meaning high enough vapor pressure) or unstable
under the unfluence of UV or ozone that the disappear,
the result being the plastic [n] is no longer plastice [adj]:
it gets brittle and crumbly, e.e., plastic that ain't so
plastic any more.
Quiz on Friday.
rgds
\SK
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