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Post by photoman290 on May 28, 2014 2:01:10 GMT -8
just found this. looks like it may be relavant to the discussion. only scanned the intro so far. www.azom.com/article.aspx?ArticleID=3171just checked the price of ultrafine perlite powder. £4 for 100 litres around 10kgs. so it is cheap enough. cant get any for a week or so as the manufacturer is moving to a new site. |
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Post by smarty on May 28, 2014 5:40:51 GMT -8
Thanks for that. It looks like they have in mind a refractory application that is constant use rather than frequent thermal cycling, on/off, use. It remains to be seen how well this stuff deals with thermal cycling. I think that the GRP-style lay-up technique suggested by Karl might be the way to go as opposed to the monolithic concrete-style casting that they are using here. It all remains to be seen, but it certainly seems that there has to be SOME use for this stuff. It all looks very promising and exciting!
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Post by smarty on May 29, 2014 1:14:22 GMT -8
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Post by photoman290 on May 29, 2014 2:55:35 GMT -8
very interesting article. i like his style. "concrete month" indeed, i am drifting between "refractables month" and "yurt insulation month" at the moment,but i digress. a link to the paper he was basing his experiments on. torusdome.com/?page_id=808hopefully i should have both sorted by next winter. |
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Post by Deleted on May 29, 2014 6:51:40 GMT -8
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Post by photoman290 on May 29, 2014 10:48:01 GMT -8
just been looking at ebay ads for sodium silicate in powder form. anyone know the ratio of water i need to add for our application? looks like 4 sodium silicate to 6 water seems the norm.i raed that once mixed it will react with the oxygen in the air so buying it in powder form seems a good idea.
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Post by Deleted on May 30, 2014 3:35:54 GMT -8
just been looking at ebay ads for sodium silicate in powder form. You may also look for TSP/90 or TSP substitute cleaner. |
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Post by photoman290 on May 30, 2014 8:48:37 GMT -8
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Post by smarty on May 31, 2014 13:57:34 GMT -8
Having rooted about my place now for any likely geoploymer chemicals and having ordered some sodium silicate and caustic soda I now have identified the following candidates: Aluminium powder (possibly for making some kind of foamed geopolymer) Aluminium trihydroxide (synthetic onyx), Flyash, Fillite (aluminosilicate bubbles), colloidal silica, Frost damaged and dried out Collidal silica ( be good if i could put this to good use) Molochite flour, Molochite sand, Molochite granules, perlite granules, Silica sand, bentonite clay, fireclay, grog, Hydrated lime, talc, piles of wood ash, polypropylene fibres, Glass fibre chopped strand mat, tiny scraps of carbon fibre mat.
It feels like I have an embarrassment of riches here if only I could put it all together into the right stuff!
My online researches have shown that talc is very un-reactive, which is an absolute fucker because it would be so good to make mass stoves out of. my completely half-arsed (so far) practical researches have so far shown that Its almost irrelevant what you mix in with sodium silicate it kind of gels real quick and I imagine sets completely just in air. I mixed it with Aluminium powder I mixed it with molochite flour, i mixed it with wood ash, I mixed it with colloidal silica and molochite (went off like lightning). All just throwing stuff together to see what happens and get a feel for things - lets face it I'm no chemist. I even found some bicarbonate of soda and thought 'that looks like a chemical, lets see how that mixes in" (it set instantly and didn't foam up like i'd naively hoped.)
What I want to get somehow is a composite that is hard on the inside and soft and spongy on the outside, cheaper and easier to make than casting in refractory concrete. It could be either constructed as a laminate shaped over a mould as in normal GRP lay-up, or cast in slabs that are later stuck together with geopolymer glue and reinforcing much like you might assemble something out of wood or sheet materials. If the lay up method then it needs a workable pot-life, and wetting out consistency, if the latter option then it needs to be pourable and set in a workable time-frame. Ideally it wants to cure at room temperature with no special provision for keeping in moisture. The slab casting method is easiest if this is not possible.
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Post by Deleted on Jun 1, 2014 3:29:02 GMT -8
Aluminium powder (possibly for making some kind of foamed geopolymer) Aluminium powder and lye release hydrogen and heat. (As a child I made stink bombs, by adding some sulfur) Alkali Activated Aerogels aka foamy geopolymers ritdml.rit.edu/bitstream/handle/1850/10097/FSvingalaThesis06-18-2009.pdf?sequence=1If you cannot disperse it in water again, dissolve it in lye and you will get waterglass Actually that is good, as chemical changes would also change properties, heat properties included. Foaming up would only happen in acid environment. |
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Post by smarty on Jun 1, 2014 7:37:45 GMT -8
I had another play around today after picking up some Mr Muscle drain cleaner and yes, Karl, you are quite right the aluminium powder reacts strongly with the caustic soda. I found that the ability of the colloidal silica to disperse more Molochite / Metakaolin was best for creating a foam, I mixed the aluminium in with the colloidal silica and Molochite flour then quickly stirred in some Mr Muscle. I have a pot of the resulting foam outside which I'm leaving to stand until it sets (if it sets) then i'll try heating it up to see what happens. I tried straight water glass and Molochite which set up and looked promising until I hit it with a propane torch and it bent out of shape, and bubbled up like popcorn.
Next up I have mixed some powdered drain cleaner with water which I'll leave overnight before adding to sodium silicate tomorrow. I'll then add this to some Molochite and make a paste. I think I'll do one batch of thin poured slurry, sprinkled with malachite granules, another layer of poured slurry with more granules and so on for three or four coats then maybe backed up with a few coats of thicker paste and Glass fibre - all cast in a food container and then left to set. I'll do another batch where I try and build it up over a former of some kind to see how closely the characteristics of the usual resin lay-up can be replicated. I think the key to the success of this is going to be controlling pot-life. The recipe I'm using gives a 1 Hour pot life, which is a little long. I'll look into ways of accelerating this tonight, 1/2 hour would be better.
I have also added some drain cleaner granules directly to some sodium silicate which i'll leave for 24hrs. This might be better for making nice and sticky geoploymer for laminating and glueing stuff.
I'll mix some colloidal silica and caustic as well and leave this to stand overnight. This might be better for runny, pourable, mixes, and foamed insulation experiments. I'll probably try the talc (Thanks Karl - Good news then) in with this mix too.
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Post by Deleted on Jun 1, 2014 7:49:00 GMT -8
The Si/Al ratio of Kaolin is 1 and the waterglass/lye mixture will not raise this significntly.
To get a Si/Al ratio of about 1.7 or higher some additional Si is needed.
Diatomaceous earth has a much faster dissolution and reaction rate than low alumina clay or stone powder.
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Post by smarty on Jun 1, 2014 12:34:36 GMT -8
I actually have some silica flour too, should I mix this in with the molochite? 50/50 say? Or I could add fly-ash which has more Si than Al?
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Post by Deleted on Jun 2, 2014 0:10:38 GMT -8
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Post by mintcake on Jun 2, 2014 8:47:28 GMT -8
The question I have is how refactory this will be. I read in something from the perlite institute (or whatever they're called) that you can make waterglass+perlite, but it's only good up to 600°C.
Since the waterglass is already alkali, is that mix showing us what the melting point of the geopolymer, or only the melting point of something else.
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