>>> But this is my problem: Glas frit is a substance like sand, how do I attach >>> this to the wires so that I can melt it on there? Or do I pre-melt it and >>> then place the mass on the pins? >> Normally, frit is used to join glass to glass. Were you planning on using >> it to insulate the wires? I wouldn't suggest doing that. > > OK, I think I misunderstood this, then. I was talking about the wire > insulation, because I do not know which substance to use for that.
Yeah, glass frit isn't the right substance to use for that. > It shouldn't be too tough to make an aluminum oxide slurry to put on wires to > insulate them. May need some >> sort of binder that you can drive out with heat and vacuum during tube >> processing, but hopefully not. Failing that, hunt >> around for some other substance you can paint the wires with that won't >> perturb the vacuum too much. > > Do you really mean aluminum oxide? It has the melting point at over 2000°C. Yup. To paraphrase from this useful document on insulating vacuum tube heaters: http://www.pmillett.com/file_downloads/Heater.pdf "A suspension is prepared of a very pure, fused and milled alpha alumina in a solution of methanol, aluminum nitrate salt, and distilled water. The alumina particle size usually ranges from 5 microns to 40 microns. The methanol acts as a suspending agent for the fine alumina particles and evaporates quickly as the wire passes from the suspension into an air furnace. The aluminum nitrate salt acts as a low-temperature binder. It cements the alumina particles together as each layer is built up during a "drag" coating operation. The specific gravity of the suspension and the speed of the coating machine are adjusted so that after 8 or 10 coats, the coating is built up to the desired diameter. It is then baked and dried between 600° and 800° C." For your purposes, you could just paint a thick paste onto the wires you want to insulate and then bake the whole thing. There is no need to melt the alumina itself, just drive off the solvent and activate/melt anything you're using to cement it in place. - 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.
