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Topic: Alumina aerogel as refractory material  (Read 3147 times)

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Offline Sylar

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Alumina aerogel as refractory material
« on: March 05, 2013, 01:07:16 PM »
I'm interested in building a forge, mainly for playing around with flux crystallization of corundum (ruby/sapphire), but I want it to be versatile for other things I might want to do in the future.

General Requirements:

    Withstand temperatures up to 1400 C (2550 F) for months at a time (crystallization can have very slow kinetics)
    Walls with a thermal resistance of at least 1 m2*K/W (otherwise I'd be spending tens of thousands of dollars to keep the furnace at temperature)
    Electrical resistance heaters (MoSi2 or other)
    Somewhat air-tight to allow for manipulation of furnace atmosphere through gas injection
    Interior volume of ~8 cubic feet


Aerogel is pretty much the only suitable material I've found that will give my furnace walls an acceptable thermal resistance without having to have walls that are 4+ feet thick. I'm concerned that at high temperatures the aerogel might sinter and after several duty cycles, might degrade as thermal insulation. My concerns come from this paper: https://e-reports-ext.llnl.gov/pdf/242911.pdf

Any thoughts on the suitability of aerogel as forge insulation, or on my plans in general?

Offline billnotgatez

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Re: Alumina aerogel as refractory material
« Reply #1 on: March 05, 2013, 03:01:52 PM »

Offline Sylar

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Re: Alumina aerogel as refractory material
« Reply #2 on: March 05, 2013, 03:45:03 PM »
Yes, very similar to that.

Obviously, for my needs slow warm-up would be almost irrelevant and reducing power consumption would be my top priority.

Does anyone have experience with aerogels? They seem kind of finicky and time-consuming to make, what with all the solvent exchanging, but if I built a supercritical dryer with a large chamber, it wouldn't take a prohibitively long time to make 8 cubic feet of aerogel.

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