Re: Spark gap erosion resistance

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Peter Lawrence by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Peter.Lawrence-at-Sun-dot-com>


I've been having the best success with tungsten-carbide spark gaps, but 
last weekend I looked up W-C in my "machinery's handbook" and it says
of the most commonly available carbide insert formulations (C2 and C5):

type "C2" tungsten carbide is "usually" relatively pure tungsten-carbide
in a cobalt binder,

but type "C5" tungsten carbide is "usually" a mixure of tungsten-carbide and
titanium-carbide and tantalum-carbide, in a cobalt binder.

This got me a little worried, isn't tantalum a very poisonus metal, can
someone look this up please (is there a materials safety data sheet web
site that we can all bookmark?).

Thanks,
Peter Lawrence.


>
>Original poster: "Jonathan Peakall by way of Terry Fritz
<twftesla-at-qwest-dot-net>" 
<jpeakall-at-mcn-dot-org>
>
>Terry, All,
>
>I have been using some of Marc's bullets in a static sucker gap, testing my
>new power controller with a sort of throw together coil. . Oddly enough, my
>experience seems opposite to yours, I am seeing fairly quick degradation of
>the bullet. After a total of less than 20 min run time, the bullet measures
>.015 shorter than a new one, and the top is visibly flattened. I tried to
>post a picture of it, but for some reason my FTP program (get right) doesn't
>show the temp folder.
>
>I figure I must be power arcing or something. This set up is behaving odd, I
>haven't had time to figure it out yet but I am having to set the gap closer
>than I used to to avoid backfire in the safety gap. The bullets never get
>more than slightly warm on operation. Any idea what I'm doing that's
>roasting these 'odes?
>
>Jonathan Peakall
>
>> Hi All,
>>
>> While testing my CW coil for Marc, I noticed that the "bullet" inserts he
>> sent me are extremely resistant to erosion.
>
>
>