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Author: Subject: Carbon Foam Refractory Made From Bread
Jstuyfzand
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[*] posted on 2-11-2016 at 05:01


I wonder how different temperatures affect the structure and properties, I recall reading that higher temperatures lead to more graphitization, which would benefit the electrical conductivity.
Too bad temperature control is not easily done in a wood fire, you'd need a kiln of some sort.
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[*] posted on 2-11-2016 at 07:12


Quote: Originally posted by Jstuyfzand  
Too bad temperature control is not easily done in a wood fire

Add more wood.

Blow air through it.

Use charcoal instead of wood.

Use coke instead of charcoal.




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[*] posted on 2-11-2016 at 07:54


Quote: Originally posted by aga  
Quote: Originally posted by Jstuyfzand  
Too bad temperature control is not easily done in a wood fire

Add more wood.

Blow air through it.

Use charcoal instead of wood.

Use coke instead of charcoal.


*Precise* temperature control I correct myself.
But your way will work, and produce different results, what its all about.
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[*] posted on 2-11-2016 at 08:16


'Precision' is a relative term.

In the good old days when people Did stuff and were not enslaved to the internet, the temperature of a furnace was guaged by the colour of the flame/coals/lining bricks.

Steel workers could give you an estimate to +/- 20 C for the range from about 500 C to 1000 C, and better accuracy below 400 C, all simply by the colour of the metal.

Hardly 'precision' but certainly a degree of Control.

http://www.stormthecastle.com/blacksmithing/blacksmith-steel...

Reminds me of the way that electricians used to check for the presence of high voltages.

They'd use a piece of pine wood, jam it onto the contacts, then slowly run their hand up the wood to see if they got a tingle ! Crude, but worked.




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[*] posted on 2-11-2016 at 10:08




When this is done to wood it turns to charcoal and will burn. When done with bread it turns to carbon that is a refractory.
Perhaps the wood is not being heated enough to turn it from charcoal to refractory carbon?
If it worked with wood it would be great . You could carve out the shape you wanted, say a box shape for a furnace to be, fire it up and you have a carbon box. Just add the door and elemetns.


The original pyrometer

post-31235-13349793025463.jpg - 211kB
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MrHomeScientist
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[*] posted on 2-11-2016 at 10:36


I'm sure the density difference is why wood doesn't turn into 'super wood'. Bread is far more porous.

This would be a neat experiment to try for sure. What's your procedure for determining iodine number?
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[*] posted on 2-11-2016 at 11:39


Quote: Originally posted by MrHomeScientist  
What's your procedure for determining iodine number?

The ASTM procedure.

http://www.sciencemadness.org/talk/viewthread.php?tid=63181

There's a link to the full document which details the procedures and calculations.

In breif, grind up then weigh sample, add 5% HCl and boil 30 secs to remove sulphur, add 0.1N iodine solution, filter, titrate some filtrate with 0.1N sodium thiosulphate solution.

Standardisation required KI as well.




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[*] posted on 2-11-2016 at 11:59


Quote: Originally posted by MrHomeScientist  
I'm sure the density difference is why wood doesn't turn into 'super wood'. Bread is far more porous.


It is part of the answer. Bread is not only porous, it is uniformly porous in three dimensions (if you knead it right), and yes has much lower density.

Wood's porosity is not uniform, but tends to the "bundle of straws" model.

Another factor with wood is that charcoal making is actually exothermic over much of the heating range, which is involved with the depolymerization of lignin, not found in flour. This is quite different from carbonizing bread.

But is you tried carbonizing the very low lignin, highly porous wood called "balsa" you would get something similar to the bread carbon foam, I expect, but again - it is a bundle of straws and would be strong in only one direction.

And some charcoal is "super wood" - look at activated charcoal which is (or can be) hard and porous and a decent insulator.

[Edited on 2-11-2016 by careysub]




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[*] posted on 2-11-2016 at 12:07


The next obvious step is to find more porous starting materials and then think of ways to 'dose' them with some reagent(s) before pyrolysis to increase the surface area further.

The key, i assume, is understanding why the carbon remains in a relatively strong matrix post-pyrolysis, and does not end up as a pile of black dust.

Perhaps pre-treating is what S.C Wack and Sulaiman alluded to, although i have found no evidence that it is beneficial to do so.

[Edited on 2-11-2016 by aga]




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[*] posted on 2-11-2016 at 12:36


I agree with Aga, this topic is good one for further amateur work at extending it.



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[*] posted on 2-11-2016 at 12:49


Having read the scientific paper, it's clearly a bunch of chancers with access to some great analysis gear who just made some charcoal.

Good on 'em !

This field is wide open to literally Anyone who has an interest in it.

Plenty more materials out there to try out.

I guess the Target is important - what properties are the most desireable ?

Surface area
Heat resistance
Structural integrity
Electrical conductivity
Chemical inertness

[Edited on 2-11-2016 by aga]

[Edited on 2-11-2016 by aga]




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[*] posted on 2-11-2016 at 13:41


My particular interest is its usability as a high temperature insulator.

Above 1650 C there aren't many options - Kaowool 3000 gives out at this temperature, as does even ultra high temperature castable refractories.

That this material is good to at least 2000 C is notable. There are other carbon products out there (graphite felt, etc.) but most of them are either not suitable for insulation or readily available to the amateur. The ability to manufacture this stuff in quantity very cheaply and to desired shaped is a big deal.

One thing that is lacking in the paper information about its performance as a thermal insulator at high temperature. The conductivity of all materials goes up with temperature, and room temperature region conductivity measurements are at best an indirect measure of high temperature performance.

Unfortunately the best insulating value was found for incompletely pyrolyzed bread, while at high temperatures obviously pyrolysis is going to completion even if it didn't at the manufacturing stage.

At least the fact that it is black bodes well - radiation is a major heat transport mechanism in porous solids at high temperature.




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[*] posted on 2-11-2016 at 14:47


This seems like the kind of thing deltaH would be interested in. A shame we haven't seen him for a while.

Aga, tell me about the mechanical properties. In my mind I cannot get past the image of burnt toast which is really brittle and crumbly. It is notable that the shape of the material distorts on pyrolysis. This is not an issue if your intent is to grind it up to powder. But if you want it as a refractory then there are additional requirements.




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[*] posted on 2-11-2016 at 15:03


Quote: Originally posted by j_sum1  
It is notable that the shape of the material distorts on pyrolysis. This is not an issue if your intent is to grind it up to powder. But if you want it as a refractory then there are additional requirements.


Umm... carbonize an entire loaf and carve it to shape?

A sanding block would work wonders.

For insulating a large volume (like the inside of my conceptual 10 gallon can furnace) you should bake wide flat loaves (make a "pizza box" carbonizing oven) and stack them up.




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[*] posted on 2-11-2016 at 15:10


The slice of bread, pyrolysed, retained it's shape.

To snap the resulting bit of carbon requires some effort, but not a lot.

Slice of bread, tinfoil, fire, verify all of this for yourself.

It takes just 1 hour.

I despair at these questions when you can know for yourself, first-hand, in just 1 hour.

[Edited on 2-11-2016 by aga]




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[*] posted on 2-11-2016 at 15:23


My apologies aga. I know your enthusiasm for Doing Stuff. Unfortunately my living and work arrangements at the moment do not afford me much opportunity for even something as simple as a fire in the back yard. It will all change in a few weeks. In the meantime I am involved in discussion, thinking and asking questions. So don't despair.



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[*] posted on 3-11-2016 at 10:18


Sorry for banging on about Doing stuff.

One kind member has pointed out that other people may not enjoy the same freedoms that i do, and that seeing things done is as close as they can get most of the time.

I guess i don't appreciate how free i actually am compared to others.




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[*] posted on 3-11-2016 at 12:47


Just put a roll of bread wrapped in aluminium foil into the wood stove. I am curious how this turns out...
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[*] posted on 3-11-2016 at 13:05


Five minutes in the library can save you an hour in the lab, or however that quote goes. If you have the experience, people might as well ask first.

I'm quite interested to try this out myself at some point.

If the goal is to exclude oxygen, I wonder if including some baking soda in the tinfoil pack would help? It would decompose into CO<sub>2</sub> and help keep air away.

[Edited on 11-3-2016 by MrHomeScientist]
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[*] posted on 3-11-2016 at 14:18


Quote: Originally posted by metalresearcher  
Just put a roll of bread wrapped in aluminium foil into the wood stove. I am curious how this turns out...

Do so, and tell us how it turns out, if you're actually curious. It's not difficult to do, at all.

Quote: Originally posted by MrHomeScientist  

I'm quite interested to try this out myself at some point.

Do so, and tell us how it turns out.

Enough words about toasting bits of bread.

Time for supposedly Amateur Chemists, members of ScienceMadness.org to demonstrate that they can, at least, make Toast.

An Egg on top is optional.




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[*] posted on 3-11-2016 at 14:49


You know aga, you're the one who's been Talking the most in this thread by complaining about people not Doing Stuff after you did one simple experiment, and it's starting to get very annoying to those of us who are following along with the thread.

It's admirable that you took the initiative and were the first one here to try it out, but you don't have to hold that over the head of anyone who wants to ask you additional questions about your results, or openly hypothesize modifications to the procedure.

Maybe you've forgotten that the experiment is not the only part of the scientific method.




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[*] posted on 3-11-2016 at 15:32


You have to admit it's a really easy experiment. Might be even feasable to quad rap one piece of bread in aluminum foil and cook repeatedly in a standard toaster. Beside that, aga did do a test for activation of the resultant char.

Would be nice to see a few other members content them selves with a simple toast bit now, use that product to do more pondering on for a latter more scientific approach. And get aga to do a round 2, perhaps with activation chems from his other thread, an easy to reproduce method using common lab glassware pieces, testing further blanketing effects etc.

I got off work a bit early today and am really going to do at least one piece to check it. Mind you I'm outta town working and have no "lab" to speak of. Just some electronics project stuff, adjustable power source and some plating chems. Not work related, just for hobby.

Which has me wondering if it will take a Ni coating. Hopefully I'll get as much done soonish. The plating bath, may be tricky. Nice green colored sol. full of soluble Ni around children is ill advised unless properly planned. He will be 3 in January so... all go and not so much a ponderer of consequences :)





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[*] posted on 3-11-2016 at 16:50


Let me throw out another possibility for this process. Suppose you pre-soaked your bread in a solution of Pt salts. Might you then get a catalytic product with a really high surface area? It could be rather useful.

(Now, it would be nice if this brought the Ostwald process within the range of home chemists but with the oxidising conditions the supertoast™ won't survive.)

[/random ramblings]




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[*] posted on 3-11-2016 at 16:54


Just an hour ago I made burnt toast.

I took 2 slices of white bread, pushed them together, then wrapped the whole deal in 10 layers of foil. I followed the usual procedure for making charcoal, putting the bread and foil in the hot coals of a campfire. After an hour I got a black mass looking very much like a squashed piece of toast (the two slices had "morphed" together) .

After cooking, the two slices (now one piece) weighed 12.52 grams. I didn't weight the bread before cooking though.

I tested the electric resistance with a multimeter set to 2000 kOhms, and couldn't get a reading even with the electrodes right next to each other. It is a very good electrical insulator it seems.

As far as mechanical strength, it is actually a fairly sturdy material. It took some force to snap it by twisting, and pulling a piece apart with my hands took several seconds. Imagine snapping a pencil in half, but a little weaker.

Tomorrow I will apply the blowtorch to it, and see how that goes.

Oh, and here's a picture-
http://imgur.com/0SROKxF




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[*] posted on 3-11-2016 at 18:10


Jsum: I was looking through patents for something posted some time ago, leaves/roots retted down to the skeleton were soaked in iron acetate and baked in nitrogen gas to make iron carbides.

Anyhow came across some patents for lignin/cellulose/asphalt substrates which were bound with quaterntary amines to form functional sites, then metal ions were chelated to the sites and it was toasted with a microwave at attainable conditions to form nano metal oxides in matrix. But for some reason every time I coppy and paste a link from my phone, it crashes the browser... Super annoying. So hand coppied: https://www.google.com/patents/US20130233802

There were others, but its family time atm.
[Edited on 4-11-2016 by violet sin]

[Edited on 4-11-2016 by violet sin]




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