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Materials Test: Alumina Mache...Success!  RSS feed

 
Chris Burge
Posts: 88
Location: Spokane, Washington
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In a nutshell:

*Took a ~1.5"x1.5" square of 1" thick alumina fibre mat (ceramic wool, inswool, durawool, kaowool, etc.)
*Mixed up a thick slip of fireclay (stir-able, but not quite pourable)
*Peeled the little cube into three layers and saturated each one with the clay slip
*Pressed the layers back together-- trying to force as much air out of the fibres, and as much slip in, as possible
*Formed the now 1.5"x1.5"x0.5" clay/fibre pad around a piece of 9/16" tubing, resulting in some what of a "C" shape (I did this because I wanted to fire the material with the fibres 'stressed' to see if they might spall or expand)
*Took the little C-brick off the form and allowed it to dry completely before firing it in a little 4" J-tube furnace I mocked up in the fireplace using kiln bricks, clay slip, and a piece of 4"x18" schedule 40 pipe (total riser height: 25")
*Burned it nice and hot for about two hours and then let little stove cool overnight before pulling off the riser and fishing out the sample

--Out came an extremely light, quite hard little specimen of a fairly durable material that has that "tink" sound that comes from a ton of trapped micro-airspace. The sharper edges of the "C" are not brittle and would probably survive some mild abuse. There was a slight amount of expansion, but nothing that would be of consequence in a fully formed and cast system.

The final intent is to be able to 'alumina-mache' a cardboard form, let it harden, and then pack it into a larger form with clay/perlite/fiberglass mix, let that dry a bit and then burn out the cardboard core using a temporary riser that can be switched from on side to the other so that the feed tube side will get hot enough to harden completely. This will give me the ability to create a fire core with a more organic form and less right angles. I can't wait to hear what it will sound like when it burns...

 
Chris Burge
Posts: 88
Location: Spokane, Washington
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Below is a photo of the alumina mache on the left, and another test firing of a different material that is a 3:1:1:9 mix (fireclay:sharp sand:chopped alumina fibre mat:perlite) with just enough water to make it hold together, pressed into a little flash from the past called a 'film container', dried out and fired for about the same time and temp.



The little brick on the right is not quite as light as the alumina mache, but it is much harder.

I'm thinking the alumina mache might be ideal as a riser material and the conglomerate would be more well-suited for the feed tube and burn tunnel.
 
Shane McKenna
Posts: 50
Location: Utah
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Thanks for doing that test Chris!!!

I really like the idea of doing a burn tube this way. Like I commented in the cast combustion chamber thread, being able to tilt the feed tube and burn tube 30 deg, will give a shorter burn tube, and get the upward burn flow going starting from the feed tube. I suspect stronger draft, and rocket effect will be possible. I have seen rocket stoves with a welded burn tube with that kind of shape that can really throw a flame out the top.

Way big thumbs up!!!
 
Chris Burge
Posts: 88
Location: Spokane, Washington
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here's a video of the little stove i used to fire the test samples

(sorry it's a little dark )

link
 
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