Interesting technique Lindsay. I'll have to show you my technique for this. Glassing the inside and outside of copper, much stronger seal. Thanks for sharing !! 👍
Thanks Vic! I seem to remember trying glassing inside and outside by melting on a ring of glass then trying to roll it over to the inside but my skills weren't exactly up to it ;-) Do you bother with the "borating" thing at all on copper? Most papers I read talk about it, but I found it impossible to get a uniform coating, and I really couldn't see the purpose if you can create an oxide film on the copper by heating anyway.
Thanks - you might, mapp should certainly be hot enough, the problem would be whether the flame is localised enough to limit the heated area. Most of the little handheld bottle torches have quite a diffuse flame.
Nice work. At 1.30 you go back and forth with the flame, doesn't this stress the glass? Maybe better to put flame at larger distance and slowly come closer.
Very useful video! What is a maximum operating temperature of this sealed? What kind coefficients of linear thermal expansion for this glass? Thank you!
very nice video. is it possible to consider this kind of joint fully sealed? I may want to use for gas transfer at pressure up to 3 bar. is it sealed at this pressure?
It is perfectly gas-tight, hence its use on high-vacuum systems long ago. However, for your application, this is probably too complex - since your gas line is under pressure, it's much easier to use a mechanical joint such as an O-ring compression seal instead. No need to attempt difficult glassblowing!
It's pretty much the same process - turn the tubing to a very thin feather edge and seal the glass to it. I haven't done it myself, but seen it described in papers.
Thanks for the video, can a Glass (or Quartz) tube be fixed to a Stainless Steel plate using some glue. The needs to be vacuum tight...please share your idea on it. Thanks in advance.
Glues are not vacuum tight and they outgas under high vacuum. It might be ok in coarse vacuum for short time. Maybe there is vacuum tight special glues. But outgassing is the reason why glues are not used with vacuum devices.
I would have though there would be an issue with differing coefficient of expansion between the materials but but guess copper and glass aren't a problem
That's the whole point of Houskeeper seals - they are used where the expansion coefficients of the two materials _don't_ match. For example, soda-lime glass is about 8ppm/°C while copper is 16ppm/°, double. But here it works, becuase the soft copper can stretch to accomodate the difference.
@@imajeenyus42 thanks for the reply. I've not heard of this, I was just searching for how I'd go about sealing feedthrough electrodes into vacuum tubes. I gather tungsten oxide as in burned tungsten wire works well with borosilicate but seeing this and since I have metal lathe and bits of copper I might try sealing a test tube round some copper like this
@@SodiumInteresting If you're looking to seal into soda-lime glass, a nickel/iron alloy called Alloy 52 works well. Getting hold of some in small quantities is impossible if you try and get it from "proper" suppliers. However, there's two sources that might not be obvious at first! One is glass reed switches. The wires used in them are the correct alloy, and you can simply break them up to use. I've actually got a page on this at my site here: imajeenyus.com/vacuum/20101027_reed_switch_wires/index.shtml The other source I found a few years ago is e-cigarette suppliers. Apparently the e-cig people obsess over different sorts of heating element wire, and you can actually buy Alloy 52 (aka NiFe52) wire for this purpose. Here's one supplier in Germany - www.zivipf.com/epages/63862298.sf/en_GB/?ObjectPath=/Shops/63862298/Categories/Heizdraht/NiFe52
@@imajeenyus42My interests are in chemistry glassware and plasma/vacuum stuff where strength and resistance to heating will be important. That's not to say I won't have use for soda-lime so thanks I'll save those links. I'm guess different glass types don't stick or seal together well, then you could coat the alloy in soda-lime glass and then attach that to borosilicate? probably simpler to find an alloy for borosilicate
@@SodiumInteresting Yeah, you'd really need to use an alloy suitable for borosilicate - there's too much of a difference between soda and boro (again about double) to join them. Kovar is a suitable alloy for Boro, and I think you can use tungsten as well if it's small.
Kami Star Hi - it's not so much the flame temperature, as the actual temperature of the metal. You probably want something in the range 500-600C to start building up the oxide. I used my oxy-propane torch to gently heat one of the tube and let the heat travel along, but you could equally well use a butane torch.
This was used and still sometimes is used in high vacuum systems used for manufacturing of semiconductors, anti-glare layers of lenses, physical experiments, electron tubes and many other fields where an extremely tight seal is required. Most vacuum systems are sufficiently tight with epoxy glue or o-ring rubber seals and similar materials.
Interesting technique Lindsay. I'll have to show you my technique for this. Glassing the inside and outside of copper, much stronger seal. Thanks for sharing !! 👍
Thanks Vic! I seem to remember trying glassing inside and outside by melting on a ring of glass then trying to roll it over to the inside but my skills weren't exactly up to it ;-) Do you bother with the "borating" thing at all on copper? Most papers I read talk about it, but I found it impossible to get a uniform coating, and I really couldn't see the purpose if you can create an oxide film on the copper by heating anyway.
@@imajeenyus42 I do wrap it on the inside. I don't bother to borate the copper, unless process.
So glass and copper can tolerate each other!
It's been used in vacuum tubes for decades.
Thankyou. I've been looking for a good video to explain and demonstrate this process and this was Excellent. Again thank you.
MONSTER Thanks for commenting, glad you liked the video!
This is great!
Thanks for posting!
Would a mapp torch achieve this 🤔
Finished result is beautiful
Thanks - you might, mapp should certainly be hot enough, the problem would be whether the flame is localised enough to limit the heated area. Most of the little handheld bottle torches have quite a diffuse flame.
@@imajeenyus42 yes, I have hho torch but flame is too small. Hopefully at some point ill get oxy propane kit and maybe a glass blowing torch
Nice work. At 1.30 you go back and forth with the flame, doesn't this stress the glass? Maybe better to put flame at larger distance and slowly come closer.
Very useful video!
What is a maximum operating temperature of this sealed?
What kind coefficients of linear thermal expansion for this glass?
Thank you!
very nice video. is it possible to consider this kind of joint fully sealed?
I may want to use for gas transfer at pressure up to 3 bar. is it sealed at this pressure?
It is perfectly gas-tight, hence its use on high-vacuum systems long ago. However, for your application, this is probably too complex - since your gas line is under pressure, it's much easier to use a mechanical joint such as an O-ring compression seal instead. No need to attempt difficult glassblowing!
Also can this be done with borosilicate?
Hello. What type of glass and what metal did you use?
How would this process differ for steel/stainless steel
It's pretty much the same process - turn the tubing to a very thin feather edge and seal the glass to it. I haven't done it myself, but seen it described in papers.
Could this be done with nichrome wire coils wrapped around the lower part of the copper coil and super heating to this color?
David Graham nope nichro will melt with the torch.
Thanks for the video, can a Glass (or Quartz) tube be fixed to a Stainless Steel plate using some glue. The needs to be vacuum tight...please share your idea on it. Thanks in advance.
Glues are not vacuum tight and they outgas under high vacuum. It might be ok in coarse vacuum for short time. Maybe there is vacuum tight special glues. But outgassing is the reason why glues are not used with vacuum devices.
I would have though there would be an issue with differing coefficient of expansion between the materials but but guess copper and glass aren't a problem
That's the whole point of Houskeeper seals - they are used where the expansion coefficients of the two materials _don't_ match. For example, soda-lime glass is about 8ppm/°C while copper is 16ppm/°, double. But here it works, becuase the soft copper can stretch to accomodate the difference.
@@imajeenyus42 thanks for the reply. I've not heard of this, I was just searching for how I'd go about sealing feedthrough electrodes into vacuum tubes. I gather tungsten oxide as in burned tungsten wire works well with borosilicate but seeing this and since I have metal lathe and bits of copper I might try sealing a test tube round some copper like this
@@SodiumInteresting If you're looking to seal into soda-lime glass, a nickel/iron alloy called Alloy 52 works well. Getting hold of some in small quantities is impossible if you try and get it from "proper" suppliers. However, there's two sources that might not be obvious at first! One is glass reed switches. The wires used in them are the correct alloy, and you can simply break them up to use. I've actually got a page on this at my site here:
imajeenyus.com/vacuum/20101027_reed_switch_wires/index.shtml
The other source I found a few years ago is e-cigarette suppliers. Apparently the e-cig people obsess over different sorts of heating element wire, and you can actually buy Alloy 52 (aka NiFe52) wire for this purpose. Here's one supplier in Germany -
www.zivipf.com/epages/63862298.sf/en_GB/?ObjectPath=/Shops/63862298/Categories/Heizdraht/NiFe52
@@imajeenyus42My interests are in chemistry glassware and plasma/vacuum stuff where strength and resistance to heating will be important. That's not to say I won't have use for soda-lime so thanks I'll save those links.
I'm guess different glass types don't stick or seal together well, then you could coat the alloy in soda-lime glass and then attach that to borosilicate? probably simpler to find an alloy for borosilicate
@@SodiumInteresting Yeah, you'd really need to use an alloy suitable for borosilicate - there's too much of a difference between soda and boro (again about double) to join them. Kovar is a suitable alloy for Boro, and I think you can use tungsten as well if it's small.
Whats the flame temperature you need to obtain copper oxide ?
Kami Star Hi - it's not so much the flame temperature, as the actual temperature of the metal. You probably want something in the range 500-600C to start building up the oxide. I used my oxy-propane torch to gently heat one of the tube and let the heat travel along, but you could equally well use a butane torch.
***** Thanks Lindsay i'll try to make copper oxide like your video .
Is this useful?? i mean, I'm a plumber, how do i use this?? What is it used for? nice video though
This was used and still sometimes is used in high vacuum systems used for manufacturing of semiconductors, anti-glare layers of lenses, physical experiments, electron tubes and many other fields where an extremely tight seal is required. Most vacuum systems are sufficiently tight with epoxy glue or o-ring rubber seals and similar materials.