laminated glass tubes
Bernhard Kuemel
I make display glass tubes with high pressure content (up to 200 bar).
To protect the tubes from damage and to protect the spectators from
shrapnel in case of an explosion I try to make a protective cover.
Previously I used polycarbonate tube which is strong enough, but is easy
to scratch and may turn brittle eventually. So I'm looking for something
that will last 100+ years. I try to make laminated glass tubes. Filling
the 1-3mm gap between concentric glass tubes with polyester produced
bubbles as the polyester shrunk when it set.
Can you recommend other materials to fill the gap? They should ...
last very long (100+ years)
excellent optical clarity
The temperature range might be -40 °C (cold weather) to 70 °C (inside a
car in full sun).
Preferably they should be...
tough
low viscosity so I can get them in the gap
index of refraction and thermal expansion similar to borosilicate glass
- 1,52 and 5 * 10^−6
not too expensive
Currently I'm thinking of ...
1) hydrocarbon gel such as in gel candles. It might be fluid enough so
it will not detach from the glass surfaces when its volume grows and
shrinks with varying temperature. But I'm afraid the hydrocarbons might
evaporate.
2) crystal clear polyurethane resin.
3) crystal clear silicone or modified silicone/silane (MS-polymer)
4) Other crystal clear sealants
Actually just a simple (viscous) liquid (glycerol) might do the job, if
it could be sealed in the gap reliably.
Thanks, Bernhard
jonnie
"Bernhard Kuemel" <bern...@bksys.at> wrote in message
news:47006$4b2b8cfc$557f66e5$13...@news.inode.at...
> Hi!
>
> I make display glass tubes with high pressure content (up to 200 bar).
> To protect the tubes from damage and to protect the spectators from
> shrapnel in case of an explosion I try to make a protective cover.
>
Try waterglass mixed with a sealer
Else use fiberglass threads - used on High pressure Nitrogen tanks
Bernhard Kuemel
> "Bernhard Kuemel" <bern...@bksys.at> wrote in message
> news:47006$4b2b8cfc$557f66e5$13...@news.inode.at...
>> Hi!
>>
>> I make display glass tubes with high pressure content (up to 200 bar).
>> To protect the tubes from damage and to protect the spectators from
>> shrapnel in case of an explosion I try to make a protective cover.
>>
>
> Try waterglass mixed with a sealer
You mean fill the gap with water glass and seal the end with e.g. silicone?
> Else use fiberglass threads - used on High pressure Nitrogen tanks
The inner pressure tube must remain visible. Look here: This is a
pressure tube with a polycarbonate protective tube:
http://darsie.dyndns.org/bernhard/ebay/co2/dsc_0368.jpg
This is a 60 mm OD, 7 mm wall protective glass tube breaking at a test
explosion:
http://darsie.dyndns.org/bernhard/CO2/co2.mp2.mp3lame.mpg (4.4 MB)
http://darsie.dyndns.org/bernhard/CO2/co2.avi (3.4 MB, same video,
higher compression)
Bernhard
Uncle Al
>
> Hi!
>
> I make display glass tubes with high pressure content (up to 200 bar).
> To protect the tubes from damage and to protect the spectators from
> shrapnel in case of an explosion I try to make a protective cover.
Try? There is no "try." Do, or do not. 200 bar is 2900 psi, in
glass! If there is no boom today there will be boom tomorrow.
> Previously I used polycarbonate tube which is strong enough, but is easy
> to scratch and may turn brittle eventually. So I'm looking for something
> that will last 100+ years. I try to make laminated glass tubes. Filling
> the 1-3mm gap between concentric glass tubes with polyester produced
> bubbles as the polyester shrunk when it set.
Use polycarb with a weather package, like exterior use Uvex.
Hardcoating the outside (e.g, eyeglass lenses) can compromise shatter
resistance.
> Can you recommend other materials to fill the gap? They should ...
Use tempered glass tubes for greater strength. Molten salt ion
exchange will temper a fully fabricated (empty) tube. However, any
added surface flaw will explode the tube. You still need a surface
coating - and you cannot do any glassblowing after tempering.
> last very long (100+ years)
Use a thicker tube, temper it, then any applied protective surface
hardcoat. Go from borosilicate to aluminosilicate. That stuff is a
bitch to work in a flame.
> excellent optical clarity
> The temperature range might be -40 °C (cold weather) to 70 °C (inside a
> car in full sun).
>
> Preferably they should be...
>
> tough
> low viscosity so I can get them in the gap
> index of refraction and thermal expansion similar to borosilicate glass
> - 1,52 and 5 * 10^−6
> not too expensive
>
> Currently I'm thinking of ...
>
> 1) hydrocarbon gel such as in gel candles. It might be fluid enough so
> it will not detach from the glass surfaces when its volume grows and
> shrinks with varying temperature. But I'm afraid the hydrocarbons might
> evaporate.
>
> 2) crystal clear polyurethane resin.
>
> 3) crystal clear silicone or modified silicone/silane (MS-polymer)
>
> 4) Other crystal clear sealants
>
> Actually just a simple (viscous) liquid (glycerol) might do the job, if
> it could be sealed in the gap reliably.
>
> Thanks, Bernhard
You've got safety and aging issues. The usual approach is a
ruggedized tube inside an adequately thick, replaceable polycarbonate
shield assembly.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz4.htm
jonnie
> jonnie wrote:
>> "Bernhard Kuemel" <bern...@bksys.at> wrote in message
>> news:47006$4b2b8cfc$557f66e5$13...@news.inode.at...
>>> Hi!
>>>
>>> I make display glass tubes with high pressure content (up to 200 bar).
>>> To protect the tubes from damage and to protect the spectators from
>>> shrapnel in case of an explosion I try to make a protective cover.
>>>
>>
>> Try waterglass mixed with a sealer
>
> You mean fill the gap with water glass and seal the end with e.g.
> silicone?
wont work for that pressure and time. Why 100 years? all tubs burn in two or
three years.
JEMebius
The Boerhaarve Museum in Leiden, NL ( http://www.museumboerhaave.nl/ ,
phone +31.71.5214224) possesses a small sealed glass tube containing liquid CO2. In a
9-month exhibition this tube was heated up to about 40 Celsius and cooled down to room
temperature (about 20 Celsius) over and again.
The CO2 turns supercritical and back to subcritical each time the temperature passes 31
Celsius. The critical pressure is about 70 * 10^3 hectopascal = about 70 atmospheres.
It looks like a piece of conventional glass-processing, obviously small and thick enough
to take pressures way beyond 70 * 10^3 hectopascal. I guess it is made out of quartz.
Apparently it withstood the countless pressure changements.
The museum staff probably knows how to obtain or to manufacture this kind of glasswork.
Good luck: Johan E. Mebius
Charles
It seems that part of your problem is solved by manufacturers of current
transparent armor systems (multi-layered glasses + polymers).
Try to Google "transparent armor" and you'll have some good ideas.
You will be able to find out the most mechanically resistant glasses &
glass-ceramics in use in that market. See for instance materials like
BOROFLOAT�, ROBAX� (SCHOTT), Vycor (Corning Inc.), TransArm (Alstom UK
Ltd) and similar.
Beside widely used polycarbonates, the polymers currently candidates as
component to compose multilayered transparent armor systems are mostly
transparent nylons, polyurethane and acrylics.
Polyurethane seems to be the best but in order to have something with
good optical properties see Simula Polymer Systems Inc for instance.
Hope that could help.