On 04/06/2013 04:23 PM, Jim Lux wrote:
On 4/6/13 6:55 AM, Bob Camp wrote:
Hi
On Apr 6, 2013, at 9:39 AM, Jim Lux <[email protected]> wrote:
On 4/6/13 6:08 AM, Lester Veenstra wrote:
Any TimeNutter worth his/her salt can do that..right!
$100 Presto 23 qt canning style pressure cooker, electric heating
elements, thermocouple probes, some fiberglass insulation to reduce
conductive losses.
Do it in your backyard and have a straw broom handy to detect
hydrogen fires.
Be careful.. 400C is getting close to 660C aluminum melting point.
I'm also not sure the gasket in the pressure cooker can take that
temperature.. you might want to replace it with something else.
Here's the reaction vessel:
http://www.target.com/p/presto-23-quart-aluminum-pressure-cooker-canner/-/A-660065#prodSlot=medium_1_5
Now, if it's the 1000C+ that Magnus mentioned, that's a bit
trickier.. Probably need a ceramic container.
Gee, another use for the Big Green Egg…. I wonder how BBQ grease
impacts the annealing process :)
I suggest heading on down to the garden store for some clay pots..
I don't think I would want 1000+ C hydrogen running around in a lash
up system. There are just to many ways for things to go wrong.
John Strong's book has a picture of how to do it.. Shows small flames
(invisible, of course) coming from the lid of the ceramic crucible
wrapped in resistance wire and immersed in some sort of refractory sand.
I've seen hydrogen brazing being done at a TWT manufacturing plant, and
it's pretty low tech. One could definitely do it in your backyard, maybe
even your apartment balcony. I don't know that I'd be generating the
hydrogen by using aluminum foil in pool acid, but that's more out of
laziness than anything else: getting a tank from the local gas supplier
is pretty easy. The pressure of the H2 is basically slightly over
atmospheric. Heated to 1000C, it's going to ignite where it leaks out,
which is good, so you don't have a problem with hydrogen accumulation
(and even that isn't an issue in the backyard) Since the flames are
invisible, that's why you need that broom. (or the fancy IR viewing
goggles, I suppose)
Back in the 80thies I skipped school to go to the university and play in
their lab I made high-temperature semiconductors. We had to do
essentially the same thing, but our target temperature was 950 degrees
and it was oxygene environment. The over was essentially a ceramic tube
with heating wires... just a large power resistor. Very low-tech. It's
really the hydrogen environment which makes it a bit tricky, but having
a continuous flow of hydrogen and just some minor blocking, and a pilot
flame to burn of the leaking hydrogen if it has not been burned of
should suffice. I think the main issue will be sourcing the right oven
components, but just setting once's mine correctly they should be
attainable. The power-bill is the issue.
Cheers,
Magnus
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