Why tungsten wire and why weld copper to tungsten? Also book recommendation?

[Miles Thatch]

1) I was watching some nixie production videos and a question came up. Is tungsten wire used because this metal offers the most appropriate seal with glass? One of the videos where a nixie was made in a garage showed that tungstan turns a coppery color when, as commented, properly seals with the glass.

2) Another question came up when watching this video: 

https://www.youtube.com/watch?v=q7I61d27R3E&ab_channel=jdflyback

Here I've seen copper wires be spot welded to tungsten wires. Why isn't tungsten used all throughout? Does solder not adhere to tungsten when soldering the tube onto a pcb? Or is it because tungsten is too expensive to be used in such abundance?

3) I've seen a google drive link floating around here somewhere with some books on the subject of cold cathode discharge lamps. Does that book roster have anything that focuses on manufacturing process rather than the physics and math behind the discharge?

Appreciate the guidance.

[Miles Thatch]

For question 3), seems like I have not skimmed far enough. The Weston book goes into the detail of the physical build of a cold cathode discharge tube.

[lokn...@gmail.com]

I think it probably has to do with the melting point being higher that what is required to work the glass into a sealed tube and it is then spot welded to the more cost effective copper. The same reason for old school lightbulbs using tungsten filaments I would imagine.

I found this which spells it out pretty well. 

“ It has the highest melting point of all the elements at approximately 3370 degrees Celsius, and the lowest vapor pressure of any commonly used metal. Tungsten's extremely high melting point makes it an ideal metal for structural applications exposed to very high temperatures.”

Sent from my iPhone

On Dec 26, 2022, at 18:17, Miles Thatch <milesan...@gmail.com> wrote:

For question 3), seems like I have not skimmed far enough. The Weston book goes into the detail of the physical build of a cold cathode discharge tube.

--
You received this message because you are subscribed to the Google Groups "neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+...@googlegroups.com.
To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/29af9ae8-0674-4bce-88ed-cc92eb3abe30n%40googlegroups.com.

[Miles Thatch]

That actually makes a heck of a lot of sense. I didn't even consider that wires can melt. Glass melting point is around 1700 degrees while copper is around 1,085 and tungsten is  3,422 °C.

[Charles MacDonald]

On 2022-12-26 15:26, Miles Thatch wrote:
> 1) I was watching some nixie production videos and a question came up.
> Is tungsten wire used because this metal offers the most appropriate
> seal with glass? One of the videos where a nixie was made in a garage
> showed that tungstan turns a coppery color when, as commented, properly
> seals with the glass.

Vacuum tubes often used DUMET wire as it had the same cofeficent of
expansion as the Glass used to make the seals. https://www.dumet.net/

their are literally BOOKS on the subject of Glass to metal sealing
depending on Power levels and temperatures involved.


--
Charles MacDonald VA3CPY Stittsville Ontario
cm...@zeusprune.ca Just Beyond the Fringe
No Microsoft Products were used in sending this e-mail.

[Dekatron42]

There are still a lot of companies making glass to metal seals as these seals are used in a lot of equipment's where vacuum tight seals are needed, like in satellites, so you can google "glass to metal seal manufacturers" and try to learn more from them.

/Martin

[Nick Andrews]

Very cool.  But expensive!  I aspire (possibly foolishly) to attempt such experiments some day, once I get my high vacuum station set up for lasers, neon, plasma, fusor, etc.

If I were to buy a spool of the Dumet wire, would anyone like to get some of the wire to play with to help share the cost a bit?

--
You received this message because you are subscribed to the Google Groups "neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+...@googlegroups.com.

To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/4b240fb9-8489-e597-f743-99884ff52760%40zeusprune.ca.