Mellin

Home made refractory

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Can veegum/zircopax be used in place of kasto lite 30? Will I have to follow a different process to apply this and cure/fire? Does this need to be formed and fired professionally to a higher temperature?

Can cerium oxide also be added to increase its emissivity? Are there any other low cost additives that will give better performance?

 

High Heat Refractory formula
Zirconium silicate 97%, added to Veegum T 3%, forms a dense mold-able low shrinkage refractory. The Veegum will lower its rated temperature somewhat below zirconium silicate’s 4550 F rating; it has low thermal expansion ( giving terrific thermal shock resistance); it should be excellent for use as thermal tiles, crucibles, burner blocks, and for lining flame nozzles. 

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I have been able to make some nice shapes with a mixture of Zirconinum silicate, Molochite (calcined Kaolin) and Bentone (similar to Veegum, different brand) I had it fired as a porcelain at my local potter but small tiles can be fired in your forge. Getting the ingredients at a pottery supply in small quantities can also prove costly compared to other refractories. The aforementioned mixture roughly costs 6 dollars per pound. I would not be able to answer your question regarding cerium oxide as I have no hands-on with it. (Also pretty happy with Zirconium silicate mixtures I have tried so far without additions)

Picture below is my latest experiment, still in the green state. A flat floor and half a tube. (it has survived firing but have no pictures yet.. I will start a separate thread with more details as I build a forge around it.) It is a little over 5 mm thick. 

IMG_20180310_110637.thumb.jpg.09e13e454dc27992d08b2f68ced377e4.jpg

 

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Great work,  Monkey Forge! What percentages in the mixture?

I hope you'll write about your exploits in the Forges 101 thread so your post can continue to be easily accessed in the coming months.

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These particular pieces contain paper fiber which I mainly used for the added green strength and it somewhat speeds up the drying. Also I knew I needed to transport them. For the percentages I used:

- Zircon             66.91%     (or 82.19% minus water and paper)
- Bentone         2.23%       (or 2.74% minus water and paper)
- Molochite     12.27%     (or 15.07% minus water and paper)

- Paper fiber     3.72%
- Water             14.87%

  I will do a complete write up later. I am curious to see how this performs under heat. Next step is to make two parts for the front and back of the half cylinder, insulation and a shell.

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A man has to realize his own limitations, so when it comes to chemistry I"ll leave it all to you guys

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I picked up the materials because I am confident in my ceramics skills but I  

25lbs of zircopax

1 lb of veegum t

ordered

8 oz cerium oxide in the mail.

 

The formula I am going off of uses 97% zirconium silicate, 3% veegum t which is easily formulated in grams and why I feel that the metric system is superior. I don't know how much water to add to the mix for say a 100 gram dry mix or how much cerium oxide to add or if it is even worth adding.

I'm roughly going to estimate 3g veegum t mixed into 15g pure water, then into the zircopax/cerium oxide mix . I read digital fire on both sintering and zircopax and it actually has me really excited and confident.

 

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Maarten will you be doing forge welding on your bottom slab with flux, and if so do you believe the floor will stand up to the abuse. 

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I was thinking to make an additional tile that slides in and out of the half tube. As the half tube sits on top of the slab. I intend to take the whole assembly to welding heat and weld. Even though the tile may be resistant to flux, molten borax will leave a bit if a mess so it is nice to be able to take a part out for cleaning. I have high hopes for flux resistance in this material but for now it is untested. Seeing is believing. :) . The test tiles I made before are very hard and dense even at 5mm and also very resistant to shock an abrasion. On a side note, uncoated ceramic wool will melt when exposed to molten borax. A simple thin coating of zircon, blanket rigidizer and kaolin will prevent this, though not indefinitely. Some other members here may attest to that.  

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Maarten please make a write up on your adventures I feel a little afraid to as I tend to jump the gun and make an idiot of myself. I'm the gag reel of incorrect forge making techniques.

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Thank you Mike for all of your help and thank you for taking the time to become the expert. I was told a proverb when I was young that goes along the lines of "it's better to be silent and thought of as ignorant rather than speak and be known as ignorant" like I said I should slow down and take my time more but it's against my nature.

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Yes, I've reached expert status, whatever that means; as long as I keep learning, it probably won't hurt me (much) :)

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Merlin,  The project happens to be a successful experiment. I had some failures which I then analyzed. That is mainly the trick to improving results. Either that or following a known, proven plan to the letter :)  I just like mucking around and seeing what happens to learn how stuff works. As Mike says you seem to be doing fine. Just take notes of what you are doing and do your best to understand why stuff did/did not work.

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Mike, Maarten I am really excited I found a patent on the use of cerium oxide as a highly emissive coating. https://patents.google.com/patent/US5668072

I really think it has potential the temperature zones are almost ideal, neutrality to acids and bases, ability to use pretty much ANY of the preferred RIGIDIZERS or Sodium silicate or veegum/ bentonite/hectorite as the binder. They also bring another technique up which I'm sure is common knowledge in the ceramics/potters world (but I haven't seen discussed here) and that's to use ethyl alcohol to alter viscosity I don't know if that could be applied independently to even the zircopax/veegum mix. 

This is what I do all night. I cant stay on one topic I just finished the forges 101 thread and was thinking about where I had heard about cerium oxide aside from the glancing blow mention of cerium oxide early on in the gas forges thread. 

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I have seen cerium oxide described as the best re-emissive agent and zirconium oxide as second best. Also, cerium oxide has no problems with phase shifting at various temperatures complicating its use in refractories. I never investigated it because I assumed it would be even more expensive than zirconia. zirconium silicate makes an end run around all zirconia's issues, so I looked no further.

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Only twenty bucks a lb.? Actually, that is cheap. Now I'll have to take a second look at it for thin coatings :)

:D zirconia is about ninety bucks a lb., and the stabilized version is a third more. For thin coatings(;ess than .040") is needed to use a re-emissive coating on a crucible. I think about more than forges :D 

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I want to explore a few different lines of this.  For thin coatings Cerium oxide with Veegum binder,  cerium oxide with colloidal silica binder, then I want to try a zircopax cerium oxide mix with Veegum binder as a brick.

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I want to give myself a little challenge, what I want to do is to build a semi scientific instrument/ forge/ furnace.

I am contemplating doing a single burner D forge with a Sealed pass through and a spot for a thermocouple to measure temp accurately my case will be made of sheet metal probably 18 gauge, behind that will be 2 inches of 8lb 2300 degree Kao-wool hardened with colloidal silica. I will then make a form or build the chamber in slab with preformed burner ports using a standard mixture of three percent Veegum t and ninety seven percent Zircopax plus aka zirconium silicate ( I use the trade name because that is what I bought). Unless I find a better available method of agitation I will use boiling water and a hand drill with a shear vane attached to put the Veegum T into suspension, as I have never done this before I will most likely use an induction cooktop to keep the water boiling as I mix because I want this stuff to work its best if that sound like overkill please let me know. As a final coating I will be attempting a mix that is cerium oxide bound by either Veegum or colloidal silica the dried ratio will be anywhere from 95-5  through 85-15. This will form the backbone of my forge. With inspiration from Maarten I will be attempting to make a floor plate that can be removed from the forge out of at least two different starting compounds the first being made from the same batch of material as the forge interior case. Floor plate number two will be made out of 48.5/48.5/3 Cerium oxide-zirconium silicate-Veegum t. A possible third floor plate could be attempted out of 97/3 percent cerium oxide-Veegum T however this seems to be a fully untested mix and could fail horribly. Having a forge capable of producing and handling temps upward of 2300 degrees would make that less likely. 

My goals in doing this are to create a long lasting small forge that is propane powered. Next I want to see be able to measure the performance of my burners and see how hot I can get the inside of that forge. 

This is my plan I will probably keep it mostly secret while its being built and post a full build and review.

Any advice before I get started?

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Sounds like you have a plan.  If you have the option to fire ceramics I would recommend making some small test tiles or even making the a couple of floor sized test tiles so you can use them in case of success. If you want a good comparison for reflectiveness you may best start with an uncoated chamber, e.g. just the zircopax "pot"  and floor, coat after a couple of uses. Good luck and keep us posted. :)

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You read my mind Maarten, I may even invest in a go pro to film my adventures. I'm assuming I will mess up a couple times and I hope 25 pounds of zircopax is enough retries but I will heed your advice by starting with making floor tiles and have everything fired professionally to cone ten then once confident I will continue with the actual chamber. my dream of a one piece inner chamber is probably not going to happen that is lofty even for project Prometheus...

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