Sciencemadness Discussion Board

High temperature in microvae oven soooo easily ???

Friedrich Wöhler - 15-2-2004 at 16:45

Searching google I found a German page
where they described a glas manufacture in a stupid simple mcirowave oven.
I was thinking, what an extra-terrestric material must be to found what absorbs these 2,5 Ghz so completely like water...
But they used simplest refractory clay as "energy collector".
Left picture shows a normal flower pot filled with refractory clay (light brown in photo) with a porcellain-labor-crucible. Its safed with some graphite powder against baking on.
They write, just 60 sec after switching on, content of crucible was completely glowing.

I don' believe.....

clicking a smily [ :o ] in subject, its never shown... (?)

[Edited on 16-2-2004 by Friedrich Wöhler]

Polverone - 15-2-2004 at 17:14

<A HREF="">Microwave melting of metals</A>

Friedrich Wöhler - 15-2-2004 at 17:16

Oh oh! Shit, I had a mistake! :D (I become too old, time to go fifty centimeters under grass...) Only the glas mixture was glowing!
Thus an ideal energy absorber must be a material with similar structure like borosilikate-glas but much higher melting point...
quartzglas maybe....?

Has anyone such glas to test it?

Polverone - 15-2-2004 at 18:29

When glass is heated, ions become mobile. Therefore the glass becomes electrically conductive, and it can be heated from induced currents moving through it. So pre-heating glass with a torch and then tossing it in the microwave oven while still hot allows it to become very hot indeed.

<A HREF=" v=/groups%3Fq%3Dmicrowave%2Bmelt%2Bglass%26hl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8%26scoring%3Dd%26start%3D10%26sa%3DN">melting a rock</A>
<A HREF=",999975186,999968998,999940043, 999922946,999708482,999445079,999963976,999963807,999941574,999812123,999906552&" ;>melting a beer bottle</A>

I rather like this high-temperature microwave experimentation. When I have a bit of extra money to pick up a second microwave, I plan on seeing how one can be (ab)used for high-temperature chemistry.

Friedrich Wöhler - 15-2-2004 at 19:29

...When I have a bit of extra money...

Hmmm ?? :o :surprising:

Still never been on a recycling place? Never got an old microwave oven for 3,-- $ or totally cost-free?

Tomorrow I'll send you a cargo ship full of them! :D

Anywhere I did a General short-test, dismantled a magnetrone from an oven and installed it provisionally at a some bigger iron-pot, containing bit of water. Worked great, in few seconds water was hot. Nevertheless I read, dimensions of oven are accurately adjusted on wave-conditions.

...Wöhler still feels and counts in D-Mark, not in 'Euro'...

Geomancer - 15-2-2004 at 19:40

Yes! I too have been interested in this. Apparently there is nothing special about the 2.5GHz frequency. Although water has well defined rotational frequencies in the vapor phase, liquid water molecules interact to absorb over a broad range. Most people say silicon carbide is the best susceptor for high temperature work, although Reid prefers graphite/magnetite. Any finely divided conductive material will also do, notably Al powder.
A while ago I carried home an old microwave someone left out as trash. After thoroughly washing it out, I discovered I didn't remember how to connect the control circuitry or the magnetron polarity. Also, I have yet to obtain any refractory material. I'll get back to it some day. For now, I'm occupied with my charcoal furnace (for phosphorus). It's not as efficient or elegant, but still impressive in its own way.

Friedrich Wöhler - 15-2-2004 at 19:56

anyone in usenet wrote

> Top 10 things to do when you've drank your last beer:
> 10) Spin the foam around in the bottom of the bottle and sigh
> 9) Toss the bottle in the trash can
> 8) Wipe you're mouth with your shirtsleeve
> 7) Belch
> 6) Take a big whiz
> 5) Sit and think, "What am I going to do now?"
> 4) Get the bottle back out of the trash
> 3) Wipe the unknown substance from the bottle
> 2) Put the bottle in the microwave, set to high power
> 1) Post the details to usenet