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Author: Subject: Microwave Kiln "Microkiln"
un0me2
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[*] posted on 29-8-2010 at 19:43


This is probably the best review of the idea I've yet seen. It describes the use of MW Irradiation for the preparation of glasses, the sintering of glasses & the film formation on glasses. It has some very useful information.

NB For those who are interested in mounting a reflux condenser through the top of a domestic MW, the schematic of how it HAS been done is in this paper.:cool: (they enclose the bottom half of the condenser in a metal Farraday trap).:D

Attachment: Kharissova.Kharisov.RuizValdez.Review.the.Use.of.MW.Irradiation.in.the.Processing.of.Glasses.and.Their.Composites.pdf (1.8MB)
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[*] posted on 30-8-2010 at 17:52


Quote: Originally posted by 12AX7  
Not at low temperatures. Calcium silicate is a primary ingredient in glass, an insulator.


Insulators are a very loose term when it comes to Electromagnetic frequencys in the range of radiowaves and microwaves. A HF tesla coil makes glass(as with almost every other substances iv tried) act like a conductor. This was the reason tesla was so gung ho with his project in the first place since it would eliminate the need for wires allowing the entire landscape and infact the air itself to be the conductor for the electric.





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Mr. Wizard
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[*] posted on 31-8-2010 at 05:58


A very easy OTC source of SiC would be 'wet or dry' sandpaper.
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[*] posted on 31-8-2010 at 16:57


Or one could just buy SiC grinding wheels which would more then likely pose less of a hassle in extraction and be cheeper. A few minute in the microwave would remove most of the materials such as binders and glues leaving you with SiC and possible some alumina oxides or whatever other rarefactory material they may contain.




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watson.fawkes
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[*] posted on 31-8-2010 at 17:34


Quote: Originally posted by Mr. Wizard  
A very easy OTC source of SiC would be 'wet or dry' sandpaper.
Quote: Originally posted by Sedit  
Or one could just buy SiC grinding wheels [...]

What are you all on about? You can buy SiC grit, in bags. Search for "silicon carbide grit". Or visit a lapidary shop, real or virtual.
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[*] posted on 31-8-2010 at 19:01


http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=28049...
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Mr. Wizard
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[*] posted on 1-9-2010 at 09:14


Yes, SiC is available in many places and ways. I just mentioned it as a source, not THE source. The fact it is already spread out on a flat waterproof carbon based sheet might help attach it in certain situations.
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[*] posted on 1-9-2010 at 11:43


Quote: Originally posted by Mr. Wizard  
The fact it is already spread out on a flat waterproof carbon based sheet might help attach it in certain situations.
Granted, although it would take quite a burnout process, and then you still need a binder for it. I would have to imagine that using sodium silicate (or other refractory binder) is easier. Disclaimer: I've never tried either myself.
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[*] posted on 1-9-2010 at 18:12


There is some indication that B4C, B, B2O3 are effective binders for SiC using microwave radiation to heat to sinter temperatures. Even BN will wet SiC if heated strongly enough.
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[*] posted on 8-10-2010 at 21:20


As a DIY sick I've been planning to make one of these kilns and found your site.I really thanks you all who wrote your opinions,I learnt a lot.

Before I found here I was trying to cover inside a red casserole with white clay (white one is stronger and is for protection of red casserole),but after reading what you wrote about terracotas I have some doubts,will that white clay protect casserole?

I found some kind of low cement concretes which contain SIC between %30-80 in İstanbul where I live (could'nt found pure SIC concrete,they contains some AL2O3 as well)http://www.remsan.com/en/06.cimento.asp

By the way this guy made his own microkiln out of firebricks and SIC,is that logical and what do you think he used as mortar to attach bricks to each other?It seems as if there is no mortar:)

This is the link
http://www.periodictable.com/PopSci/2003/09/1/index.html




[Edited on 9-10-2010 by ümit]
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[*] posted on 9-10-2010 at 20:01


As a simple microwave-heated crucible, how well would the following work?

A small glazed porcelain crucible inside a larger one, with the gap (~10mm for instance?) filled with slightly compacted 1000 mesh SiC powder.

I've tried to find the temperature up to which porcelain will hold, but my search-fu is failing me...
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[*] posted on 9-10-2010 at 21:40


Probably work well. Mind that porcelain will crack from thermal stress....

There are lots of kinds of porcelain; most are probably good up to cone 6 (~2100F / 1150C).

Tim




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[*] posted on 10-10-2010 at 04:44


Cheers Tim.

When you refer to thermal stress, do you mean heating to certain temps, heating/cooling in general, or just sudden/uneven change in temperature?
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[*] posted on 10-10-2010 at 12:52


I cracked a porcelain mortar while heating CuO powder in it in a microwave, and I doubt it (the powder) got beyond 800C just based on the glow temp. Porcelain can take the heat, but not the thermal stress - also the stresses end up being enough that it shatters fairly violently (though it did not break the glass door of the microwave). If you are determined to try it I would say that you could try to introduce some sort of insulation between the outer porcelain and the SiC susceptor (perlite? rock wool?) but I think you are better off just trying to find something less liable to crack.

(edit): Another alternative is to heat slowly. Thinking about it some more, I was running at full power (1 kilowatt) with just a few grams of powder in my mortar, which resulted in very rapid heating, maybe 15C/sec or so. If you are more sensible about the power versus susceptor mass you might well have better results than I did.


[Edited on 10-10-2010 by bbartlog]
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