> Yes, I have a few of those as well, which show no cracks or physical damage, > yet have lost gas, probably through the pins. Does anybody have any ideas on > how to fix that kind of problem? How to seal the metal-to-glass interface?
Those are well-nigh unrepairable. It might be possible to slump the glass into some sort of closure, but you'd need a jig to ake sure the pins stayed aligned. You'd probably have to cut off the envelope to fix the stem, then fuse a new envelope onto it and seal off again. > By the way, isn't that a special material between the pins and the glass, > whose coefficient of thermal expansion is somewhere in between the > coefficients of the glass and the metal? I can see an orange kind of > substance painted on the pins, at the glass interface. You're probably seeing copper oxide dissolved into glass. Since copper oxide is soluble in glass, it can make some nice seals. As copper is fairly ductile, it will flow when needed to absorb stress, taking some of the strain out of the joint. Hard pin nixies (most of the ones that aren't wire leads) generally have three-piece pins, with a center section that seals to the glass, a thick pin on the outside to fit into the socket, and stiff wire on the inside that gets spot-welded to the tube elements. One problem with reprocessing nixies is that you'll get mercury vapor into the vacuum pump and thence into the atmosphere, something some folks would be quite worried by. You'd need an induction heater to drive off adsorbed gases on the electrodes, or a vacuum furnace. But it's not impossible. I've worked in neon shops on and off for a while, and have been tempted to try this with a couple of my broken nixies (including argon or helium fill to see how it goes). However, I haven't gotten around to it yet. - Cheers, John -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
