Fusion Message Board

In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.

Subject: QUESTION: metal to glass seals and teflon
Date: Nov 14, 6:32 am
Poster: Mark Harriss

On Nov 14, 6:32 am, Mark Harriss wrote:

Just a quick question, what is the metal alloy used in vacuum tubes for the pins, that bonds to the glass??. Is it similar to invar with a low expansion co-efficient???. Also are any special glasses needed???, I have been playing around with stainless wire and borosilicate and it does not work at all, mainly due to the contraction.

Finally how usefule is teflon for vacuum seals??? I realise it kind of flows under compression, but would it work if it was a fat, square cross section 'O' ring and located in grooves?.

I have a book on aluminium coatings on glass which requires a vacuum of high quality and they are using stuff like waxes for the bell jar seal, also i have read of vacuum epoxies used in laser tubes with helium, would it be suitable???