Carbon Foam Refractory Made From Bread

Quote: Originally posted by aga

I had a hunch that Sulphur would be good, so tried it.

Quote: Originally posted by Chemetix

I don't have the time to go and try this so don't crucify me. But has anyone tried, or would like to try, dipping their bread refractory foam in a thin mix of plaster and see what happens. Or sodium silicate perhaps, just something to shield the carbon from getting oxidised.

Expecting porous stuff like bread to have good electrical conductivity does not make sense. The more porous something is, the less conductive it is. Especially carbon which even solid is weak conductor. The only useful stuff i see here is thermal insolator. But only if it's easier to make then any other thermal insolator. I mean the purpose of bread is to be porous, so we already know what properties to expect. Using it as crucible sounds impossible. Try holding water in sponge

Quote: Originally posted by RawWork

Expecting porous stuff like bread to have good electrical conductivity does not make sense.

Quote: Originally posted by RawWork

Also gases are better insolator.

Now that is worth mentioning !

Cheers. Will look at how Panko is done

Edit:

A bit of research says that Japanese soldiers in WWII invented a method to make bread using electric current. Most likely a car battery. Will give that a try.

The gluten probably gets elongated more due to the 3x 'rising' cycles. We'll see.

Bought a new Pyrolysis Rig today for 20 euros :



[Edited on 20-2-2018 by aga]

Quote: Originally posted by Chemetix

I don't have the time to go and try this so don't crucify me. But has anyone tried, or would like to try, dipping their bread refractory foam in a thin mix of plaster and see what happens. Or sodium silicate perhaps, just something to shield the carbon from getting oxidised.

Quote: Originally posted by Fulmen

Forgive me if it's been covered, but I couldn't find anything about it. Has anyone tested it's resistance to oxidation at prolonged heat?

If you call 2 minutes 'prolonged' then yes, just now, due to your question.

This slice of rye bread didn't come out too well with the new pyrolyser - it isn't conductive.

Here it is raw, subjected to 2 minutes under a 70% Butane/30% Propane flame, then the other side was subjected to 2 mins under a MAPP gas flame.







This particular sample was a bit iffy to begin with, yet shows how durable it is under heat, even in air.

After this test the toast fell apart when it was picked up. Big chunks, but definitely in bits.

For anyone interested in using this bread/carbon stuff structurally, the average shrinkage during pyrolisation came out at 27% today.

3 chunks of home made bread were measured, pyrollised in a charcoal fire, then re-measured.

Again the resistance is quite low this time measuring 11.7 ohms in a point-to-point test.





Here's the supporting data for the shrinkage figure.
Attachment: data.ods (13kB)
This file has been downloaded 414 times

Latest attempt
- the bake my own bread option went out the window with roof repairs and family time. But bbq dinner offered a shoot from the hip opportunity. These are seed pods from a tree in my yard, a sweet gum.

Pre incineration,


Post roast



I have a feeling that there may be more loss on further torment. The aluminum foil was as shiny as ever, and the cans label was faint though legible. But they are crispy/brittle. My plan to invest as little time as possible succeeded, family didn't miss me for long. Just closed the bbq vent 95% and walked away.

Every experiment leads to a wealth of ideas for next time on this one for me. Gratifying, cheap, full of room for insane detail if the free time arises.

Drive to work offers thinking time. Takeaway this morning : seed pods can retain geometry... Things like dry cereal such as Kix or cocopuffs could be great preforms... Rice crispy treats are moldable... Rice itself is fairly consistent... We can have compact or foamy preforms to use as ingredients.
,
So adulterated rice crispy treats and a crap-ton of sample compositions will eventually have to be tested.

Tried a second firing on the sweet gum balls, not measured first time. One trial of two balls lost 5.26% more on second firing. Not a tremendous amount and the shape/size distortion was minimal. Though I did not get a caliper on them during any of this.

^ v

Some lightly frosted puff like cereal. Turns out the coating makes a decent binder after ignition. They lost ~44%

Grapenuts cereal lost ~24% after two trips through the BBQ. First time they were only a deep burgundy / brown. Now a good black.

^ v

A little disappointing was a test on tapioca pearls... It did not cook evenly, the one side was exactly like a muffin pouring out. But the interior of that area was well detailed and airy. The pearls did not simply char with my limited heat control. It lost ~21.4%

Then there was a wild shot in the dark mix of wheat gluten, potato starch, Styrofoam balls and a wildly impulsive dab of numerous additives that will give little clue to their individual effectiveness... Below 1-3 , white lithium grease spray and graphite powder worked as a release.




Last from above ^ this idea was Last on and did not receive enough heat to be blackened the whole way, but tomorrow is another day. It's a stainless steam tray insert with a stainless cup set inside, the interspace filled with cereal. I foiled over the top and flip it foil side down on the grill. If all goes well, I'll have a nice foamy crucible shape. I mixed a little confectioners sugar and wheat gluten in as these were not frosted. My son was horrified when I showed him what used to be ~25g of his puffs... Had to be reassured I wasn't going to ruin them all.

We're that to succeed one could try a second coating or brush on paste for a more closed pore look. My better half got me a couple jumbo size boxes of puff cereal... Keeps me out of her kitchen, lol. Plenty of material to play with for a while now.

None of this has been really high heat and no resistance tests were performed. Just weight pre/post BBQ roasting.

Superb experimentation violet sin !

You're in lead regarding the number of different items shoved in a fire, also actual Data regarding weight change.

Definitely need the resistance measuring - you might have discovered something awesome already

Ok so the preform did not work... It easily could work, but this time was no. The whole top portion was stuck in one chunk (nicely), further down was not so. The gluten/sugar mix was not evenly spread despite misting the cereal and folding the powder in. When the cup came out, part of the lower char came dislodged and fell in the recess.

Frosted cereal would be far more convenient or just some kind of rice crispy treat like mixture. The forms are nice and so far seem well suited to my goal.



So after all this playing around with carbon char foam, and a wide field of possibilities, I narrowed down to one goal. At least first off. I want to play with high temp fun, I don't want to buy ceramic fiber blanket for the prices I've seen... So refactory foamy insulation it is. For a quick and dirty project to test these materials, I wanted to do something like a heating mantle-ish set up.

I know it's more professional to come to the table with a finished product before revealing your plans.. but I literally don't care if I fail here, in fact I'm sure I will, many times at the very least. Lol.

Basic plan is to cast a rough shape as seen above. True up the sides, trim and shape the thing. Then either paint it or wrap and refire it and then paint it with ceramic or plaster etc. Install a through way for wires and standoffs for the element.

I could easily see a small mantle for my 14/20 set taking shape with enough effort. But really the possibilities are immense. Electrodes, catalyst support, insulation... It's wide open. Best to pick one and optimise.

Newest test run, same steamer insert form and ss cup center form.


-(Pic 1): New kind of frosted puff cereal cap and rice crispy (w/ starch/sugar binder) side shot
-(Pic 2): consequence of over fill was cooking on side = separation rift largely empty.


-(Pic 3): Side shot of strata. Was surprisingly TENACIOUS grip on the center form cup,
-(Pic 4): frosted chunks, sans adulterants, really hold shape with minimal contact.


-(Pic 5): rice crispy preform from center cup, shrunk a lot, but I did add a fair amount of water to make moldable consistency.
-(Pic 6): removed chunk of last experiment.

That of course was not the sum total of objects toasted, but last time it dumped the typed words and loaded pics, assuming too much. A couple things need be further toasted.

There was a flat one with paper towel and sugar with cotton face wipes = deformed easily and cracked.

There was a ovoid shape, 2 small stainless bowls stacked face to face. But the al foil/ss bowls/al foil was a pretty effective heat shield on top of being a good form. It awaits further charting.

Bought more of the overly frosted puffs, I will be toasting them as is later today as well as trying some surface cover mixtures on the previously toasted and failed chunks. Need an atmosphere resistant cover for actual future use to move forward.

This chosen cereal may be a cheap as-is usable material here. It's almost a bit glassy when done, 48% sugar content lol. 2.49$ for a huge bag. This time Will be parchment paper-- aluminum foil-- parchment paper-- char material. I'm just gonna make a block form sans SS pan. I feel that it greatly adds to the cook time. First light was 1:30am, final check was at 5am with more charcoal added @ 3:15am while turning. HOURS in the bbq and yet not complete carbonization. Darn it.


Choice of parchment paper as effective release b/c of excruciating effort to place pieces that didn't char in that place was caused by pinhole in al foil leading it to stick to as bowl. Poor adhesion from poor charing plus sticking = F*$# me running.

No weights were taken b/c family time conflicting with hobby & family > play time hopefully mor pics and progress this evening.

Quote: Originally posted by mayko

Someone brought some nasty BlunderBread hamburger buns to my 4th of July cookout and they've been sitting in the fridge since. Finally, a use for them!

I did a few exploratory experiments with these carbon foams and a sodium silicate solution (waterglass). I tried three basic treatments:

* repeatedly soaking in waterglass, then dilute sulfuric acid, then rinsing

(Na₂O)_x·(SiO₂)_y + xH₂SO₄ -> xH₂O + ySiO₂ + xNa₂SO₄

the idea was to coat or permeate the foam with silica. The foam was baked to dry after each dunking in the waterglass, which led to the formation of many tiny sodium silicate bubbles. These structures survive the acid treatment as this photomicrograph show. At high magnification, there appear to be small silicate needles on the carbon.



It seemed to stand up to a MAPP gas torch pretty well; afterwards, the pores of the carbon foam seemed to have been filled with a bubbly/crystalline silicate



* soaking in boric acid, baking to dehydrate to boric trioxide, then soaking in waterglass

(Na₂O)_x·(SiO₂)_y + zB₂O₃ -> (Na₂O)_x·(SiO₂)_y·zB₂O₃

Boric acid was dissolved in absolute EtOH, and the carbon foam soaked in the solution. It was dried, then baked to dehydrate, then soaked again. After a couple of repetitions, this was dunked in waterglass and baked dry again. The result was a fluffy, flakey white crust on the foam. When hit with the MAPP gas, the whole structure crumpled, suggesting that the boric/silicate soak had permeated and disrupted the carbon network, such that it lost all integrity when the intersitial material melted. When examined, the silicate/boric material had melted into droplets clinging to the foam surface, which cooled into tiny beads containing air bubbles. I wonder what role the foam geometry (voids, ridges) have in forming the beads?



* soaking in copper acetate, then soaking in waterglass, then dilute sulfuric

The idea here was to coat the foam with a mixed copper/silicate layer, like you'd see in a chemical garden. After soaking in an ethanol/copper acetate solution and drying, a chunk of foam was cut open. The salt appeared to be mostly but not entirely superficial, with a small amount appearing to have made its way into the interior. When hit with a torch, a thin layer of copper was left firmly adhering to the surface.

After soaking in waterglass, drying, and then sealing with dilute acid, the surface had a light green, foamy appearance. When this was torched, it seems to withstand a lot of heat; afterwards there is a glassy red-brown residue on the surface. Under the microscope it looks to be a mix of copper metal and silicate. It also looks like the silicate is wetting the carbon surface much better in this case than the others.

I wonder to what extent the cupric ion is being reduced by the acetate ion vs. by the carbon substrate...