Re: brass or tungsten (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Mon, 09 Jul 2007 15:35:02 +0000
From: David Rieben <drieben@xxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Cc: drieben@xxxxxxxxxxx
Subject: Re: brass or tungsten (fwd)

Scott, Frank,

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.

David Rieben

-------------- 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. 
> 
> Frank 
> 
> 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. 
> > 
> >_________________________________________________________________ 
> >http://liveearth.msn.com 
> 
>