geopolymers fire paste

Discussion in 'Chemistry' started by mikal, Jul 29, 2007.

  1. mikal Registered Member

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    Does anyone have experience in making geopolymers from natural minerals?I've had quite a bit of experience. I've made them from kaolin clay powder,wollastonite (calcium silicate) diatomaceous earth, caustic soda and/or sodium bicarbonate and creme of tartar..(potassium salt).To make a geopolymer one has to have calcium together with either, but not both together, sodium or potassium compounds with aluminium silicates,that seems to be a general rule.Free silica needs to be available to and it helps if this has a large surface area like diatomaceous earth does.Also if the ingredients are more reactive , for
    example, if one uses calcined kaolin clay powder the geopolymer cures or sets at a lower temp.Also using caustic soda instead of sodium bicarbonate makes it set at an even lower temp.So I think the 'fire paste' of Troy Hurtubise is a geopolymer made from calcium bentonite clay (Fullers earth, kitty litter, this has a lot of free silica to) sodium bicarb or caustic soda with an organic component (diet coke ir citric acid) that makes bubbles with the Na bicarb and aerates the ceramic so that when it sets it has holes or cavities in it so that it has great heat insulating properties.

    mikal
     
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  3. mikal Registered Member

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    Hi this was my first post on this geopolymer thread but it got posted on another thread by accident.

    "Hi I was looking at the posts on fire paste in this forum ,that's the stuff invented by Troy Hurtubise that has very good heat insulating properties..I believe it is a geopolymer...with some organic components in it which causes holes in the ceramic during the curing process.Troy mentions that this material is made from diet coke and some low cost material that costs about 5 dollars per 45 gallon drum and that it would make people laugh if they knew what this material was.This material is I believe Fullers earth which is often used and sold as a kitty litter material because of it's absorbent properties.So two ingredients are diet coke and kitty litter (Fullers earth) the other ingredient which would make a geopolymer from the above two ingredients would then be either sodium bicarbonate or caustic soda.If bicarbonate of soda is used then the ceramic would cure at a relatively high temp.maybe around 400 to 600 deg C. If caustic soda is used the curing temp. would be considerably lower around 200 to 300 deg C.I made a really tough, light ceramic geopolymer from fullers earth, citric acid(diet coke ingredient) and bicarbonate of soda..I mixed the dry ingredients first and then added some water and pounded the stuff in a mortar and pestal till it was like a clay...the stuff fizzed first and then absorbed the water to become clay like..I formed the material into a little cube which I then cooked into ceramic on my gas stove top...the right combinations of fullers earth, citric acid powder and bicarbonate of soda powder will produce a good ceramic geopolymer without cracks that is light and tough and with very good heat insulating properties something identical or very similar to 'fire paste'."
     
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  5. old coyote Registered Member

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    mikal- I want to use this material to cast stove parts for a new stove. do you have a rough formula for mixing the materials ? thanks I hope you are still out there in cyberland!
     
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