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Post by Deleted on Jun 2, 2014 9:49:27 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. Sodium waterglass melting pont is 1,088 °C (1,990 °F). The 600°C take into account a high security value for perlite, because perlite softens at 850–900 °C (1560-1650 °F), not for the waterglass. Inflated perlite is even more sensitive to heat. At firing, if mixed with clays rich in alumina or magnesia waterglass will chemicaly react with the clay resulting in minerals with melting points raised by 500°C or more. As perlite is an aluminosilicate too, waterglass mixed with fine perlite particles will react similar to mixes with alumina clays. Kaolin geopolymers, in which the chemical reactions happen at low temperatures, have been heated to 1400 °C without any singn of melting or other damage. |
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Post by smarty on Jun 5, 2014 0:28:05 GMT -8
I think that part of the problem I'm having is finding pure ingredients. The caustic soda drain cleaner I found is mixed with sodium carbonate. the recipe I followed was for 320gm caustic soda mixed with 1 litre water, this is then left to stand 24hrs then some of this solution is mixed 1:2 1/2 with sodium silicate.
I got hold of some Diatomaceous earth and mixed to a variety of consistencies, one a sticky paste that I tried laminating with fibreglass, one a slightly more runny mix that I added Molochite granules to make a concret like substance and one that I formed on its own into a disk.
There was some evidence of Exotherm going on so something was happening but after 5 hrs or so they hadn't set up hard. I stuck them in my slow cooker on the lowest heat for a couple of hours to see if they would harden, then left them overnight. They have set to a kind of hard rubbery consistency.
This is not too discouraging but obviously not right either. I'm sure that if I do the boiling water test to see if they are sound they will turn to a sticky goo. Frustratingly the drain cleaner does;t state the proportions of the ingredients so its hard to adjust to take account of the impurity.
Trying to find a chemical company that will ship to a domestic address is proving tricky but i'll persevere I guess.
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Post by smarty on Jun 5, 2014 0:41:40 GMT -8
Good old ebay. just found the pure caustic soda on there.
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Post by Deleted on Jun 5, 2014 1:13:37 GMT -8
The caustic soda drain cleaner I found is mixed with sodium carbonate. At which percentage ? Sodium hydroxide solution Mass fraction NaOH in weight.-% ----- 4,0 - 10,0 - 20,0 - 30,0 - 40,0 - 50,0 Molar concentration NaOH in mol/l ---------- 1,04 -2,77 - 6,09 - 9,95 - 14,30 -19,05 Mass concentration NaOH in g/l ------------- 41,7 -110,9 -243,8 -398,3 -572,0 -762,2 Density of the solution g/cm3 ------------------ 1,043 1,109 -1,219 -1,328 -1,430 -1,524 Scientific papers often recomment very high mol/l ratios, which are very dangerous. Even the 4%, 1 mol/l solution has PH 14. Diatomaceous earth alone does not work, as there is virtualy no alumina in it. It is only an easily solvable SiO2 supply (relatively cheap for such fine particles) You need fine molochite powder. granules have a far to small surface for alkaline attack, only good as filler. Calcined kaolin takes relatively long, for shorter times you need some fly ash, or add 10% per wight calcium oxide or calcium hydroxide to the metakolin. The calcium oxide in the fly ash contributes to the speed. You need a high shear mixer for a drill for very good mixing. |
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Post by photoman290 on Jun 5, 2014 1:24:00 GMT -8
i found caustic at the local cheap hardware shop. it should say is pure. mine is called bartoline caustic soda and comes in 500gr plastic bottles remember it will react with air so keep it sealed and don't buy too much at a time.
i am picking up 25 kgs of 200 mesh molochite later today so will be all set for some experiments. i am away for the next month so hopefully when i return i will have lots of new stuff to read about.
after reading about roberts raku experiments i plan to make a kiln for experimenting with ceramic shell from by test rocket set up.
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Post by Deleted on Jun 5, 2014 1:46:46 GMT -8
i am picking up 25 kgs of 200 mesh molochite You need very fine powder, rather toward 1000 mesh. NaOH is hygroscopic, it will draw water from the air becoming heavier. The reaction with CO2 will not have much effect if tightly closed. |
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Post by smarty on Jun 5, 2014 5:13:16 GMT -8
Having no luck finding a supplier of suitable metakaolin. Its on these occasions when you realise how washed up this country is as an industrial producer!
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Post by Deleted on Jun 5, 2014 5:18:02 GMT -8
You wrote you have molochite flour, which is metakaolin. The powder should be cement-fine. In small mounts and without a commercial sham I can only get cement-fine grinded grog of another kind of clay. Maybe I take the cheap route with this fine grog normal Kaolin and calcium oxide or hydroxide. Cement-fine grinded grog is available at pottery suppliers. Maybe I will use the following instead of calcium oxide Prompt ((CNP ciment naturel prompt, Vicat in Grenoble) is a natural quick-setting cement from the group of Roman cements. Produced from lime and clay. www.cimentetarchitecture.com/en/content/view/full/6272 |
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Post by photoman290 on Jun 5, 2014 7:38:06 GMT -8
400 mesh is the finest sieve size i can find at a reasonable price,so looks like it is time to make a ball mill. how i will know it is fine enough i don't know.
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Post by Deleted on Jun 5, 2014 7:55:57 GMT -8
400 mesh is the finest sieve size i can find at a reasonable price That is about 0.0173 mm, maybe fine enough. |
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Post by photoman290 on Jun 5, 2014 8:05:18 GMT -8
having thought about it i could try mixing the molochite with water and pouring though a 5 micron bag filter then drying it. maybe in a microwave? bag filters for biodiesel are pretty cheap and will handle a large volume. i will start with the 400 mesh SS filter first though.
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Post by Deleted on Jun 5, 2014 8:50:49 GMT -8
pouring though a 5 micron bag filter Will not work. The finer particles are already sieved out and will be sold at a higher price, that is how the mesh system works. Cement qualty is measured in Blaine (specific surface area (cm2 / g). The higher the value the higher is the chemical reactivity. Should not be below 2200 cm²/g. If one divides a 1cm cube with 6cm2 into cubes with each half the side lenght then the resulting 8 cubes will have double the original surface 12cm2. Assumed the density is 1g/cm3 the 400 mesh will result in bout 350 Blaine. Standard Portland has 3000-3500 Blaine, which equals about 2 micron or less. The particles are irregularly shaped, thus the actual Blaine value of the 400 mesh might be higher, but even if it would be four times the value would still be relatively small. The chemical reactivity of normal kaolin may be due to the much larger surface as high or even higher as 400 mesh metakaolin. |
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Post by smarty on Jun 5, 2014 9:30:10 GMT -8
AGS Argiles & Minéraux / Imerys group, 17270 Clerac, France geopolymer precursor metakaolin ARGICAL M1200S web: www.ags-mineraux.comARCELOR-MITTAL (BSME), By-Products, Sales, Marketing and Excellence, France geopolymer precursor Blast Furnace Slag, world-wide supply www.arcelormittal.comČLUZ a.s. (České Lupkové Závody, Czech Republic) manufactures geopolymer precursor metakaolin. They supply ready to use geopolymer binders: “Baucis Products” www.cluz.czThere is a sister company to the top one owned by IMERYS I have emailed them about obtaining small quantities 25kg bag. I imagine they only do pallets. They haven't got back yet so fingers crossed.The czech company I have also emailed. they sell what look like geopolymer kits. No idea of whether they ship to UK. I found the here: www.geopolymer.org/about/business-fellows |
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Post by Deleted on Jun 5, 2014 9:42:44 GMT -8
geopolymer precursor metakaolin is only heated to 750°C,
not to sinter temperature as grog, thus it has still small particles and a large surface.
Could be done with a rocket.
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Post by smarty on Jun 5, 2014 10:30:32 GMT -8
I found this here: www.geopolymer.org/faq/new-scientific-word-for-metakaolin"Why do we have to avoid using the wording METAKAOLIN?? The word metakaolin means: another type of kaolin. It does not provide any information on the reactivity, the physico-structure, and its ability to geopolymerisation. The word metakaolin, in the industry, refers to kaolin OR Kaolinitic clays dehydroxylated, that is to say thermally treated at a temperature above 450°C. Industrial metakaolin are thermally treated either at: 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000°C. These products are used as fillers for organic plastics, rubber, paper, etc. or as pozzolanic additives in Portland cement. Above 1000°C, the products are called: chamotte, and are used in the ceramic industry. The calcined kaolinite we need for geopolymerisation is an alumino-silicate oxide with a very specific 27Al NMR spectrum, essentially with very well resonances at 55 and 20-25 ppm, assigned to Al(IV) and Al(V) coordination with O. In order to emphasize the fact that we are selecting a material containing the mineral KAOLINITE (not the kaolin), i.e. clays which contains this poly-silico-aluminate, such as: kaolin, kaolinitic clays, dickite clays, nacritic clays, and perhaps also halloysite clays, I am using the term MK-750 [MetaKaolin-750°C] (or KANDOXI, an acronym for KAaolinite-Nacrite-Dickite-OXIde). This oxide is the one, which has the NMR spectrum with Al(IV-V). In my book Geopolymer Chemistry & Applications I am using the wording metakaolin MK-750, or MK-750 alone.. Prof. Dr. Joseph Davidovits" Do you think that if we calcine Kaolin or any of these other clays he mentions in a rocket fired kiln we could make our own MK-750? I guess we would have to still find a clay powder ground fine enough to start with? Wish I could just go down the road and buy a bag of the stuff though! |
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