what epoxy will bond tungsten to teflon without outgassing?
what epoxy will bond tungsten to teflon without outgassing?
(OP)
I have some thoriated tungsten rods that I need to epoxy to a block of teflon.
Let me describe the application:
It's a high power Xenon flash-lamp. It emits 100 megawatts but only for a few microseconds and only once every 5 minutes or so in a temperature controlled lab so heat shouldn't be a problem. The body of the bulb is made from teflon with a quartz window. The electrodes are 1/16 inch thoriated tungsten welding rods that poke through the teflon into the vacuum chamber. The teflon wall is about 1 inch thick. I need an airtight seal. The pulse is brief but the rods will jump when the bulb is fired so there will be brief mechanical stress. I'll try to keep the epoxy out of the chamber and it will never be exposed to the arc but it would be better if the epoxy not out-gas into the vacuum chamber. Also, it'll be bombarded by a continuous stream of alpha particles from the thorium (they are welding rods so they're only about 2% thorium.) It'd be nice if it could hold for years but tolerable if it only lasted a few months.
Can any epoxy do this?
Thanks,
Art Blair
Dept of Aeronautics
University of Washington
Let me describe the application:
It's a high power Xenon flash-lamp. It emits 100 megawatts but only for a few microseconds and only once every 5 minutes or so in a temperature controlled lab so heat shouldn't be a problem. The body of the bulb is made from teflon with a quartz window. The electrodes are 1/16 inch thoriated tungsten welding rods that poke through the teflon into the vacuum chamber. The teflon wall is about 1 inch thick. I need an airtight seal. The pulse is brief but the rods will jump when the bulb is fired so there will be brief mechanical stress. I'll try to keep the epoxy out of the chamber and it will never be exposed to the arc but it would be better if the epoxy not out-gas into the vacuum chamber. Also, it'll be bombarded by a continuous stream of alpha particles from the thorium (they are welding rods so they're only about 2% thorium.) It'd be nice if it could hold for years but tolerable if it only lasted a few months.
Can any epoxy do this?
Thanks,
Art Blair
Dept of Aeronautics
University of Washington





RE: what epoxy will bond tungsten to teflon without outgassing?
Flash lamps are usually made from quartz tubing and use a metal to glass seal. I can't imagine that a Teflon body would maintain a vacuum without being pumped down periodically.
RE: what epoxy will bond tungsten to teflon without outgassing?
Compositepro is probably right about Teflon, though I have seen it used as electrical pass-thru materials on countless vacuum chambers (all of which were typically continuously pumped).
RE: what epoxy will bond tungsten to teflon without outgassing?
http://www.reltekllc.com/adhesives-for-teflon.htm
I would lean toward using a ceramic material to seal the feed-through Like the ones on bulbs. Sauereisen, along with others, make a variety material that will do the job.
http://www.sauereisen.com/adhesives/adhesives.aspx