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Re: Borosilicate Electrodes

Posted By: SVP Neon Equipment
Date: Wednesday, 14 July 2010, at 12:05 p.m.

In Response To: Re: Borosilicate Electrodes (John Anderson)

> Eurocom has sold boro electrodes for years.
> I think you can even buy them individually.
> Tungsten/boro seals are less reliable than
> dumet/soft glass, but I haven't had any
> issues with leaks.

The boro electrodes I have got from Eurocom seem to have a "shelf life", meaning: After they have been on the shelf for a few years the glass to metal seal starts to deteriorate. You can literally see it go from a nice gold color to blotchy brown spots and then almost completely brown/dark brown. I have done many custom hard glass to tungsten seals and this is not normal.

With that said, all neon-type boro electrodes that I am aware of are a straight standard borosilicate glass to tungsten seal. I think this is where the problem lies (in addition to quality control). Standard boro is not the best choice of glass for this purpose. I use uranium (sometimes called "canary" glass by old glassblowers) for the glass to tungsten seal, then come back and seal the standard boro to the uranium. This seems to have a much higher success rate of a leak-free seal. High-end glass/metal feed-through's that are used in high temperature and high vacuum applications also use this approach.

Messages In This Thread

• Borosilicate Electrodes -- BlueBeard -- Saturday, 10 July 2010, at 4:21 p.m.
  • Re: Borosilicate Electrodes -- Stephan Krasner -- Monday, 12 July 2010, at 5:41 a.m.
  • Re: Borosilicate Electrodes -- SVP Neon Equipment -- Monday, 12 July 2010, at 12:20 p.m.
    • Re: Borosilicate Electrodes -- BlueBeard -- Tuesday, 13 July 2010, at 12:35 a.m.
      • Re: Borosilicate Electrodes -- sean S -- Tuesday, 13 July 2010, at 1:50 p.m.
        • Re: Borosilicate Electrodes -- BlueBeard -- Tuesday, 13 July 2010, at 8:09 p.m.
          • Re: Borosilicate Electrodes -- John Anderson -- Tuesday, 13 July 2010, at 8:25 p.m.
            • Re: Borosilicate Electrodes -- SVP Neon Equipment -- Wednesday, 14 July 2010, at 12:05 p.m.
              • Re: Borosilicate Electrodes -- Howie Cohen -- Friday, 23 July 2010, at 1:14 a.m.

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