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Re: RF conductor materials (fwd)
---------- Forwarded message ----------
Date: Wed, 29 Apr 1998 22:50:18 +0000
From: randy <randy-at-gte-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: RF conductor materials (fwd)
> Date: Thu, 30 Apr 1998 08:37:20 -0600 (MDT)
> To: tesla-at-pupman-dot-com
> Subject: Re: RF conductor materials (fwd)
> From: Tesla List <tesla-at-pupman-dot-com>
>
>
> ---------- Forwarded message ----------
> Date: Thu, 30 Apr 1998 06:51:23 -0600
> From: terryf-at-verinet-dot-com
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Re: RF conductor materials (fwd)
>
> Hi Chip,
>
> At 10:29 PM 4/29/98 -0600, you wrote:
> >
> >
> >---------- Forwarded message ----------
> >Date: Wed, 29 Apr 1998 22:27:17 -0600 (MDT)
> >From: Chip Atkinson <chip-at-pupman-dot-com>
> >To: tesla-at-pupman-dot-com
> >Subject: Re: RF conductor materials
> >
> >
<snip>
> >Aluminum
> >house wiring used years ago keeps fire departments busy today :-((
> ><<<<
> >I believe that the reasons that Al wire is so bad are as follow:
> >Al-Cu connections corrode leaving small contact areas which can heat up.
> >Not necessarily as an effect of the previous sentence, an Al wire melts at
> >a significantly lower temp. than Cu.
And , I believe that the typical single-screw setup on common house-
hold breakers just squishes the Al wire, which squishes outwards over
time, loosening the connection
> Also, Al burns quite readily once it
> >gets started. As any pyro knows, Al powder can be quite flammable.
There is a process, "Cadwelding", used to fuse copper to copper or
copper to steel, which places the parts to be bonded in a graphite
crucible, which is then filled with a commercial mixture of powdered
copper oxide and aluminum powder are ignited. Is supposed to work
with materials other than copper, too. Supposedly the current rating
of the connection is the same as the conductors. Cadweld is a trade-
mark of the Erico Corp, 1-800-248-WELD. All info in this para-
graph from the Polyphaser Corp's " The Grounds For Lightning and
EMP Protection" Book (but a 1987 version of it) see
http://www.polyphaser-dot-com (if I am wrong, surf for it, it's out
there, somewhere.). The chemical composition sounds alot
like "thermite" but will leave it for the reader to reasearch that
substance. My point being, you are correct, Al powder CAN burn,
and impressively so, apparently.
>
> If AL get hot enough to melt the game is long over. AL to Cu connections
> corrode and fail as you describe. AL to AL connections must be clean and
> "gas tight" to insure that the connection will not become resistive. The
> electric power industry uses Al for everything. Those connections are
> either welded or use special clamps which bite deep into the wire over a
> very large area. These clamps often have 5 to 10 bolts forcing the
> connections to be absolutely solid. The large area of these clamps and very
> high forces used insure gas tight connections and a wide area for the
> connection. Obviously overkill for the mechanical stresses. Al has such
> thick and easily formed oxides, that it is a very difficult substance to
> work with electrically especially over long periods of time. There are
> greases that are used in industrial AC wiring which act to prevent corrosion
> by removing air and chemical action.
"Noalox" should be available at your local electrical supply houses;
This is, I believe, touted at a "conductive" grease...more or less...
I have used it on Al-Al antenna element connections with apparent
success. I have also used it on Pb-Pb and Pb-Cu connections on golf-
cart battery connections, I believe that it helped, but it may be
from keeping air out, rather than the conductive properties of the
grease. No apparent harm, at any rate.
>
> >
> >Chip
> >
> >=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> > Chip Atkinson
> > http://www.pupman-dot-com
> > --- If I can't fix it, I can fix it so it can't be fixed --
> >=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> >
> >
>
> Terry
>
>
Randy