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Re: Beryllium Oxide



Original poster: Bert Hickman <bert.hickman@xxxxxxxxxx>

Hi Godfrey,

These sound very much like vacuum feedthrough insulators. These are used to bring a high voltage into a high vacuum environment. The metal base of the insulator is usually made from stainless steel to mate with stainless steel high vacuum hardware. These appear on eBay from time to time, and often sell at a very small fraction of their original cost. For some reason (high thermal conductivity?) they always seem to be made from beryllia. Nice find!

Bert

Tesla list wrote:
Original poster: "Godfrey Loudner" <ggreen@xxxxxxxx>
Well, they look like high voltage insulators. They are similar to the
insulators on my 32kV radar transformer, but those are much smaller than
the supposed beryllium oxide insulators. Actually, the suspect
insulators are 6 inches long...top terminal--ribbed ceramic--massive
metal base--smooth ceramic--bottom terminal. There is zero resistance
between the top and bottom terminal. I don't think there is a
semiconductor inside the shaft. Because of the large size of the
conductor inside the shaft, it appears to have been made for large
currents. While it could be used for a high voltage insulator, perhaps
the primary application was for high currents; hence the use of
beryllium oxide to dissipate heat...just don't really know. I got these
items from eBay about two years ago and just left them unpacked. I
thought they would be good for a project I'm working on now; so when
they were unpacked, I saw multiple beryllium oxide labels. For the time
being, I think I'll just leave them alone. Many thanks for the warnings
to myself and others to the potential dangers of beryllium oxide...even
if it has been fired with ceramic and rendered harmless if maintained in
that form.
Godfrey Loudner
Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>
Interesting.. Not sure why they'd use BeO on a HV insulator.  It's
usually used where high thermal conductivity is needed.
Anyway, as long as you don't chip, grind, sand, etc, the ceramic,
you're fine.  Lots of high power semiconductors use BeO.
There IS a disposal issue, because you don't really want to poison
the poor guys crushing your garbage in the truck.