Re: Spark gap erosion resistance

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

Original poster: "Metlicka Marc by way of Terry Fritz <twftesla-at-qwest-dot-net>" <mystuffs-at-orwell-dot-net>

Nice work Terry,
I think the fact that carbide is actually considered a "ceramic" lends
to the no melt factor? It doesn't melt, It just turns to powder when
heated to white hot.
I imagine if the insert was used in a non cooled gap at very high power,
it would start to react like a carbon rod, but it would again get almost
white hot (that's hot!) so the holder would most likely melt first?
Thanks for being the "big gun" endorsement for carbide, I hope more
coilers switch over.
The inserts come in so many shapes and sizes that any gap arraignment
can be had. I used to hand grind diamond tipped inserts, a diamond wheel
cuts carbide like butter. so i tried my diamond tile saw (wet) just for
"low budget" shaping ability and it worked great. anyone that has one
can get carbide rod stock and shape a nice cone on the end in a few (15
- 20) minutes.
The tips i sent you were found at a carbide sales place in the surplus
bin, so a trip through the phone book might just land a few for the
lucky coilers out there? 
Thanks again, and take care.
Marc M.
Geek #1055

Tesla list wrote:
> 
> Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
> 
> Hi All,
> 
> While testing my CW coil for Marc, I noticed that the "bullet" inserts he
> sent me are extremely resistant to erosion.  Here is a picture comparing
> one to a 1/8 inch pure tungsten rod after running a big arc about the same
> length of time.
> 
> http://hot-streamer-dot-com/temp/erode.jpg
> 
> The tungsten rod is well discolored and the tip was burning off.  However,
> the bullet is hardly discolored at all on the very tip!  They should make a
> wonderful high power spark gap tip.
> 
> These "bullets" are apparently used as tungsten carbide tip inserts for big
> rock drilling bits.
> 
> http://www.torquato-dot-com/acc.html
> 
> http://www.mining-technology-dot-com/contractors/drilling/sandvik_smith/sandvik_
> smith6.html
> 
> This is something people that need super high power spark gaps should look
> into...
> 
> BTW - I am seeing about borrowing a 2500 watt power supply from work to do
> higher power testing :-))  It's three phase but can run from my home's two
> phase in a pinch...  Maybe then I will get fire balls.  If not, we have
> some 200kW ones... ;o))
> 
> Cheers,
> 
>         Terry