On Thu, Mar 23, 2006 at 12:11:54AM +0200, Peter wrote:
> > Are there any thing about this glass that are different than normal
> > glass? Especially weak?
> 
> 'weak' and 'low melting temperature' are not necessarily related. At 
> normal temperature they are as hard as ... glass. But you can take a 
> 1N4148 and hold it into the gas flame of a lighter for a couple of 
> seconds and see the glass melt.

Thanks for the info, and my new party trick. :)

> > See, I'm thinking you could easilly make Nixie tubes with this stuff...
> > The fabrication would be fairly easy at low temperature, and aparently
> > the requierments for Nixie tubes in terms of gasses and purity are very
> > similar to neon tubes. It'd be nice to be able to assemble a stack of
> > glass with the electrodes in it, and then seal it at the edges.
> 
> You have to study things like outgassing and adsorbtion and Invar (to 
> make the glass passthroughs) and getting the process under control 
> because the pressure at sealing time will be higher than when the object 
> cools off, and it may take some special magic to stabilize the 
> conditions in the tube enough to make it work reliably. I am not sure 
> whether the seal on diodes is hermetic. I do not think it is.

I may be a step ahead of your... Invar isn't used for the passthroughs,
because glass too has a co-efficient of expansion that isn't zero. There
are other methods, like Dumet seals, described very well in:

http://www.teralab.co.uk/Glass_Blowing/Glass_Metal_Seals/Glass_Metal_Seals_Page1.htm

Seriously, that website is amazing! Lots of info on how to do your own
scientific glass blowing.

Looks like some burners and glass stock are all you need for the basics,
after that it's a matter of getting a vacuum pump and other equipment. I
think I've got some space in my studio... Can probably setup some
ventilation, and summer is coming up soon.

-- 
pete@petertodd.ca http://www.petertodd.ca
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