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Post by photoman290 on May 19, 2014 13:48:32 GMT -8
checked special plasters and a bunch of others. seems i would need to buy around 75 kilos of flours and make a kiln. a tad to much investment for one j tube. nice to know about the technique though. cant seem to find anyone selling small quantities of molochite, which considering i live in cornwall is rather annoying. i am sure i could scrape enough off the roof of imeries if i went up there with a brush.
back to the refractory cement i think.
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Post by smarty on May 19, 2014 22:37:28 GMT -8
You could use grog instead of the molochite granules, it might be possible to replace the sand sized molochite with a fine grog if you can find something a similar mesh size. these are available in small quantities from pottery suppliers. Then all you need buy is the colloidal silica and the malachite flour to make the slurry with. This has many other uses/possibilities such as rigidising ceramic blanket, painting firebrick with to give a better resistance to abrasion, backing up things with an insulating layer of fibreglass chopped strand mat dipped in slurry, etc. If you are using ceramic blanket in your rocket as insulation then you can make the kiln out of this by laying it out over some chicken wire and stitching it along the edge with some nichrome wire to hold it in place then form it into a tube large enough to fit the pieces you want to fire in with a piece for the top and bottom then heat it using a large propane torch as used by flat roofers. when you've fired it you can carefully unstitch the ceramic blanket and re-use in your rocket stove. You'll need the higher temperature blanket for this though.
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Post by photoman290 on May 20, 2014 9:34:09 GMT -8
i remembered there are a couple of foundries not far from me so went along today to see if they had anything i could use. the sand casting one uses a resin based slurry that air dries in about 2 minutes. they didn't know if it would work for my application but the foreman said he would find out and let me know. they said if it works that will make me up a small quantity.
i went to the lost wax foundry about 1/2 a mile away and they have molochite 200 in 25 kg bags. they wont split a bag but will let me have it at trade price. all in all a good hunch to give them a try.
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Post by Deleted on May 22, 2014 8:25:10 GMT -8
You could use grog instead of the molochite granules, Molochite is a brand name for calcined kaolin. Bigger grains of molochite are just koolin grog. Calcined kaolin is pozzolanic active, which is only important in the presence of an activator like quicklime or a mixture of waterglass and lye, which would turn it to refractory concrete. Alkali activator: Need: - 320g lye [sodium hydroxide, drain cleaner] - 1 liter water - ~2.5 liters sodium silicate torusdome.com/?page_id=1068 |
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Post by photoman290 on May 24, 2014 1:46:21 GMT -8
no mention of how much molochite/kaolin this activator will activate? i cant find it if they do say anyway.
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Post by Deleted on May 24, 2014 4:33:23 GMT -8
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Post by smarty on May 25, 2014 8:11:24 GMT -8
I've been looking into this whole geopolymer thing Karl it is fascinating stuff. All kinds pf applications.Thanks for the lead. just ordered Davidovits' book.
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Post by Deleted on May 25, 2014 8:45:50 GMT -8
I've been looking into this whole geopolymer thing Karl it is fascinating stuff. All kinds pf applications.Thanks for the lead. just ordered Davidovits' book. Davidovits Geopolymer Chemistry and Applications is unfortunately quite expensive, like most scientific books. |
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Post by photoman290 on May 25, 2014 11:51:38 GMT -8
the subject is fascinating and has much wider applications than "our" potential uses. what suprised me was the amount of co2 it could save over portland cement. i do wonder about long term changes to the finished product in the light of some portland cement experiments over the last 50 years.especially on things like bridges and dams.
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Post by smarty on May 25, 2014 13:28:00 GMT -8
it looks like some form of this material was known to the Egyptians and Romans so in some respects at least well tried and tested.
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Post by smarty on May 26, 2014 3:42:31 GMT -8
It looks like pearlite is a kind of volcanic glass. Does this mean that it will be a chemically active ingredient of a geoplolymer?
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Post by Deleted on May 26, 2014 5:38:01 GMT -8
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Post by photoman290 on May 26, 2014 10:40:32 GMT -8
sorry to sound pedantic but, pearlite is a crystal formed when steel cools and perlite is a volcanic glass. i know we know what we mean, but could be confusing if the wording is incorrect and the context isn't known.
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Post by smarty on May 27, 2014 2:06:06 GMT -8
Cheers. Stand corrected.
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Post by photoman290 on May 27, 2014 13:33:31 GMT -8
if i have understood it correctly i could use powdered perlite instead of molochite and mix that with the activator to make a refractory cement suitable for a jtube this would be a better option than having to buy 25 kgs of refractory cement. thinking a homemade ballmill and a 200 mesh screen should work. i have most the parts to make one lying around apart from the balls. may have to read up on the size and speed needed. i have some 200 mesh somewhere.
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