[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: brass or tungsten (fwd)
---------- Forwarded message ----------
Date: Mon, 09 Jul 2007 15:35:02 +0000
From: David Rieben <drieben@xxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: brass or tungsten (fwd)
I would say that tungsten is far superior as a SG electrode material to
brass or especially zinc. BTW, I'm not quite sure why one would sug-
gest zinc for this purpose, unless it's strickly economical reasons, as zinc
has a considerably lower meltiong point (420C) than brass (900 - 940C
depending on the particular alloy) or copper (1085C). It seems that the
electrode erosion experienced with brass would only worsen with zinc.
Also, I believe zinc will oxidize quite readily when exposed to SG heat.
Tungsten has the highest melting point of any know metal (3422C), is
quite resitant to corrosion and/or oxidation and tungsten's thermal and
electrical conductivity is not that bad either. Actually, tungsten's electrical
conductivity is better than zinc or brass, per Wikipedia.
-------------- Original message --------------
From: "Tesla list" <tesla@xxxxxxxxxx>
> ---------- Forwarded message ----------
> Date: Sun, 08 Jul 2007 18:16:31 -0700
> From: Frank
> To: Tesla list
> Subject: Re: brass or tungsten (fwd)
> Brass will work if you use induction coils or static machines but
> using NST's (higher currents) the brass tends to vaporize on the arc
> face and then tarnish. The gap works for a while and then it starts
> to sputter and you have to file the faces to remove the pitting.
> Tungsten is far superior but it is hard to work with and expensive as
> you indicated.
> A good alternative is zinc! This was a popular arc electrode in 1-5
> KW spark transmitters. It is cheap and easy to thread and cut.
> You can find large cast zinc rods from pluming shops, they are in
> water heaters. If you are near a lake or the ocean (much better) you
> can find zinc anodes of various sizes for the engines and heat
> exchangers. Do a quick search and you will find 1/4" zinc rod by the
> length and cheap. Cut with a hacksaw, thread if needed and you have
> electrodes! I think zinc is even cheaper than brass.
> If you want to make a zinc disc, go to an art supply place,
> especially on a college campus, and you can buy zinc plate. Artists
> use it for print making.
> I still have some 2 ft square sheets of the stuff that is 1/16" thick
> for various projects.
> At 06:44 PM 7/8/2007 -0600, you wrote:
> >---------- Forwarded message ----------
> >Date: Sun, 08 Jul 2007 20:28:00 -0400
> >From: Scott Bogard
> >To: tesla@xxxxxxxxxx
> >Subject: brass or tungsten
> >Hey everybody,
> > A quick question, would I be better off using a tungsten rod or a brass
> >rod in a propeller rotary gap? my thinking is that tungsten would be able
> >to withstand the heat better, but it is expensive and fussy to work with,
> >and brass would conduct better and be cheaper, and I could get it in a
> >bigger diameter (making it last longer because of improved heat
> >dissipation). When it wears out, I can just move the stationary electrodes
> >in to compensate. I'm just looking for other opinions, and maybe if
> >somebody has done some experiments, that would be cool. Thanks a bunch.
> >Scott Bogard.