| Pages:
1
2
3 |
Hexabromobenzene
Hazard to Others
Posts: 262
Registered: 27-4-2021
Member Is Offline
|
|
This is my revised article on the preparation of carbon electrodes. Subsequently, I will refer to this article
Once again about binders. The main function of the binder to impregnate our filler and give carbon when heated. The binder should have conflicting
properties. On the one hand, low viscosity at room temperature on the other a lot of carbon during pyrolysis.
In industry, coal pitch are used as a binder. It gives about 70% carbon by weight. But it is not available. Sugar without modifications gives 20%
carbon when heated. Sugar modified by p-TSA can give up to 35% carbon. Theoretical limit of 40% carbon from which sugar consists.
To achieve the same carbon density as with a coal pitch, we need to tune the pumping 2-4 times, but the sugar is very affordable
About the structure of carbon. Carbonic substances can do this in 2 ways. From a liquid state and from a solid.
Substances that decompose from a liquid state produce carbon foam, which is usually very porous. It is soft and easily burns
Substances that decompose from a solid state form a piece of carbon with less porosity and hard, but they are prone to cracking at the curing stage
due to the release of water as well as at the stage of carbonization due to shrinkage.
An example of this is phenol -formaldehyde resin or epoxy resin.
Having combined 2 of these types of carbon, we get mesoporous carbon. The template formed during the carbonization of the solid polymer is filled with
carbon foam from liquid. This reduces the shrinkage and helps to crystaling the solid polymer layer.
Also, such an electrode is more resistant to burning
As the experiments above, it is very durable and is more like ceramics. It can be obtained sugar based electrode with a curing resin or using the
binders from a mixture of sugar and amino acids in a certain ratio. The binder from flour is also mesoporous, but gluten is present in the resin in
suspension, and the gelatin is soluble in water. Therefore, the quality of carbon with gelatin is better.
About graphitization. Iron leads to an increase in graphite domains at low temperatures and also changes the structure of carbon, making it more dense
and resistant to burning. At high temperatures (above 1000), the effect is not as noticeable as with lower ones.
The technique of preparing carbon electrodes is also important. You must use the optimal amount of binder. Too much the electrode will break when
baking, then too little it will lower the strength of the electrode due to the poor tuning of the pores. Excess binder is more dangerous for the
electrode. Mass should be like wet sand. Good pressing is also important. You can use hammer, but you should have a strong form. I recommend thick
cardboard pipes. Carbon should be grided as best as possible, but a small fraction of large particles will be useful. A denser carbon is preferable.
The best option is anthracite. More affordable coal from laminate floors. Repeated impregnation and pumping also improves the electrode
The final impregnation should be chemical persistent. I recommend solutions of polyethylene or polypropylene in molten paraffin
   
[Edited on 27-1-2025 by Hexabromobenzene]
[Edited on 27-1-2025 by Hexabromobenzene]
|
|
|
Hexabromobenzene
Hazard to Others
Posts: 262
Registered: 27-4-2021
Member Is Offline
|
|
As the experiments have shown these electrodes in a solution of sulfuric acid even more persistent than lead at small currents.
Also, these electrodes are more persistent than carbon electrodes for welding
Small carbon electrodes are produced by pressing powder with a binder. Homemade electrodes are produced by a impregnation carbon workpiece. Even after
the destruction of the resin, they retain the structure
|
|
|
Hexabromobenzene
Hazard to Others
Posts: 262
Registered: 27-4-2021
Member Is Offline
|
|
More images showing how the sugar-amine binder works with the addition of acids or amine salts.
Don't forget: for carbon electrodes, you need to use a large excess of sugar to produce mesoporous carbon(3-5mol excess).
The resulting composite resembles glassy carbon and gives a residue in which you can even see a reflection.
  
[Edited on 13-10-2025 by Hexabromobenzene]
|
|
|
Hexabromobenzene
Hazard to Others
Posts: 262
Registered: 27-4-2021
Member Is Offline
|
|
I repeated experiment with wheat flour hydrolyzed with hydrochloric acid(30 gr flour in 50ml mixture 2% acid). This binder lacks sugar. After adding
sugar carbon solids became dense and shiny .
However, quality of the precipitates was lower than with sugar + amine compositions possible due to oligomers. Sugar + hydrolyzed gluten, sugar +
hydrolyzed polyamide 66 (oligomers), and sugar + bone glue compositions gives best results. However, flour binder is very cheap. You can add
additional high-quality binder to the cheap one to save money, or soak the piece in a high-quality binder after baking, or both.
[Edited on 19-11-2025 by Hexabromobenzene]
|
|
|
Hexabromobenzene
Hazard to Others
Posts: 262
Registered: 27-4-2021
Member Is Offline
|
|
How to make binder test:
Apply a thin layer to a hot plate and begin heating. If the binder is good, a solid strong layer of carbon will form in which you can even see a
reflection. Thicker this layer- binder is better.
|
|
|
Hexabromobenzene
Hazard to Others
Posts: 262
Registered: 27-4-2021
Member Is Offline
|
|
I'll be working on carbon electrodes soon.
This new photo shows the result of carbonization of the best binder ever made. Carbonation was carried out on a glass plate.
Hydrolyzed polyamide 66 in hydrochloric acid plus sugar. The exact ratio isn't known, as I had a solution, but it's possible it was 1:3 to 1:5, with
excess sugar, of course.
You can see the precipitate, like glass. It's very hard.
|
|
|
| Pages:
1
2
3 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
