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Post by smarty on Aug 4, 2014 9:27:33 GMT -8
Bit of an odd one today. It seems not all potassium silicate behaves the same. Up until today I used a gardening product called potsil and it worked fine for the foamed geopolymer using aluminium. I ran out of that and started using another product I bought from Kremer Pigmente in Germany. The aluminium had very little effect. Instead I used Hydrogen peroxide which worked. Another problem is that this new potassium silicate seems to react with the lime super quick causing the mixture of powders to clump into balls if at first I add too little liquid. The potsil was less tricky and you could just add more if there was too little and still get a nice mix. This new stuff doesn't behave in the same way. I have yet to see how the new samples turn out, but I have ordered some more of the potsil since it seems to behave itself better.
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Post by photoman290 on Aug 4, 2014 11:49:07 GMT -8
hi smarty, karl told me you can make potassium silicate out of KOH and something else. it is on the other thread somewhere. the jtube one.
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Post by smarty on Aug 7, 2014 10:05:52 GMT -8
One thing that can affect how suitable a geopolymer is for use in a high temperature environment is whether it is subjected to heat in an oxidising or reducing atmosphere. I'm assuming that a well designed rocket system will be running on minimum excess air but still be slightly oxidising. Would this assumption be correct?
Has anyone actually made something with this stuff yet? The thermocouple in the kiln I have access to is broken so I've ground to a halt until I can get it going and try baking some Kaolin. The class C fly ash I have has given some promising results but I really want to see how the MK-750 works out before I decide on a recipe to try out on an actual project. I made a really promising 'looking' resin-like substance for laminating, using fumed silica - the light floaty stuff - but it didn't go off even after heating at 85 degrees for a couple of hours, so maybe I'll try that when I've made some MK-750.
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Post by Deleted on Aug 8, 2014 3:34:43 GMT -8
smarty did you have tried the fine Molochite flour ?
Molochite 200 (0-0.075mm) or some stoneware grog in this range should be fine enough.
Fumed silica alone will not work, some oxide/silicate of earth metal or alkaline earth metal is required too.
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Post by photoman290 on Aug 9, 2014 6:13:37 GMT -8
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Post by Deleted on Aug 9, 2014 6:57:29 GMT -8
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Post by photoman290 on Aug 11, 2014 11:53:24 GMT -8
i have a price for argical m 1000 10 ltr tub £17 delivered. i also spoke to imeries today. their sales manager is away till thursday but will email him for some prices. i found this list on their site in case there might be something more suitable than the argical m1000. there seem to be a lot of options we could try. i will wait for some feedback before i order anything. www.imerys-perfmins.com/eu/ProductDetail.asp?PID=5 |
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Post by photoman290 on Aug 11, 2014 14:14:07 GMT -8
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Post by Deleted on Aug 12, 2014 3:44:34 GMT -8
This site of Imerys shows the ones engineered for pozzolanic activity. www.imerys-oilfieldsolutions.com/Metakaolin.htmlMetaStar 501 is only slightly less reactive than Argical M1000, if it is significantly cheaper it would be an obvious alternative. Opacilite and Argical 1200S are likely much more expensive, but could likely activated with significantly lower PH values. |
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Post by photoman290 on Aug 12, 2014 10:34:06 GMT -8
as i can get the argical 1000 easily and it is so cheap i will go ahead and order a 10 ltr bucket of it.i have emailed the uk distributers of the imerys products and am waiting to hear from them.
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Post by photoman290 on Aug 14, 2014 7:15:06 GMT -8
checked the price of metastar 501, and as expected it is a lot more expensive. £2.50 a kilo. plus carriage. stiil a lot cheaper than metamax.
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Post by ericvw on Aug 23, 2014 16:47:26 GMT -8
Hi Karl, What about this cat, Geopolymer cement – Geopolymer Institute www.geopolymer.org › Applications Aug 8, 2014 - Geopolymer cement is often mixed up with alkali-activated slag ... The geopolymeric cement reaches a compression strength of 20 Mpa after 4 hours, .... Here is the only place to buy at a special price a bundle comprising the ... A video is embedded after you scroll down, is this a relevant application of geopolymer towards rocket stoves or something else? Curious... If no help, I apologize for wasting time, Eric VW Not exactly linking to the specific Google search result... Sorry |
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Post by Deleted on Aug 24, 2014 4:46:48 GMT -8
photoman290 has kindly provided me with samples of agrical M 1000 and molochite 200. Agrical M 1000 is kaokin calcined at 750°C to get the highest possible pozzolanic reactivity. Molochite is kaolin calcined at 1525°C to turn it completely to mullite and ensure maximal thermal expansion to get a grog with the highest possible thermal stability. Due to the extremely high calcine temperature it is the least pozzolanic reactive grog possible. As my experiments have shown molochite 200 is still reactive enough to make geopolymers. I have mixed both with 10% NaOH and place it in my oven for curing at 75°C. Agrical M 1000 quickly began to gel, molochite 200 takes significantly longer to start geling. Without any calcium both take relatively long to harden, even at elevated temperatures. Due to the much lower water demand the molochite is gaining strength much faster than the agrical, once the chemical reaction has started. The agrical will result in a less dense geopolymer, and thus have a lower thermal conductivity. ericvw Fly ash based geopolymers will have lower service themperatures than those based on calcined Kaolin, due to lower content of aluminosilicates and the thin walled bubbles. Anyway, the service temperature should be high enough for rocket stoves. BTW An about a 5mm thick piece of geopolymer made from fine grog was lying around. I have heated it with a gas torch to above 1000 ° C and then immersed in water. It did not show any sign of damage after this extreme thermal shock.
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Post by Deleted on Aug 24, 2014 6:08:51 GMT -8
At this early stage of development(24h, 10h at 75°C) the samples with
agrical M 1000 and molochite 200 are much more fragile
than the sample at the same stage, but without elevated temperatures,
with low calcium fly ash provided by STEAG Power Minerals.
The sample of agrical M 1000 is still relatively soft.
With only 10% NaOH and no calcium one will need quite a lot patience.
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Post by Deleted on Aug 24, 2014 8:26:10 GMT -8
I have mixed some more samples.
agrical M 1000 and molochite 200 with each 20% NaOH and
agrical M 1000, as the slowest, with 10% NaOH and 10% quicklime.
I have placed them in my oven for curing at 75°C.
The additional 10% quicklime make a huge difference in curing speed,
the agrical M 1000 became quite hard after just one hour.
Likely even just additional 5% quicklime would make a huge difference,
but I have no more agrical M 1000 to test it.
The additional 10% NaOH do not show much difference at this stage.
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