12332123
Harmless
Posts: 38
Registered: 14-11-2009
Member Is Offline
Mood: No Mood
|
|
Polymer bonded anodes?
I was wondering whether a small proportion of relatively inert polymer (perhaps PTFE) could be sintered with for example PbO2 to form a monolithic
inert anode for chlorate/perchlorate synthesis. This would require lower synthesis temperatures and hopefully have lower internal stresses than a
ceramic electrode while being longer lasting than a plated one. Any thoughts? would it still be sufficiently conductive? Would it work?
[Edited on 5-12-2009 by 12332123]
|
|
|
tentacles
Hazard to Others
Posts: 191
Registered: 11-11-2007
Member Is Offline
Mood: No Mood
|
|
Short answer: no. If you do some digging, there are some patents regarding this - I forget the binder they used but basically they were making PbO2
anode cores in a similar way, although they were pressure casting them around 2000-3000 psi. There was mention that they did require plating of PbO2
over top, as the core was not very conductive and did not hold up to use by itself.
|
|
|
Swede
Hazard to Others
Posts: 491
Registered: 4-9-2008
Member Is Offline
Mood: No Mood
|
|
I've been pondering this for a year now. Initially I thought that there should be a way to make a composite LD anode, or some sort of anode that
would not require plating, but apparently the results are usually less than satisfactory, and most of the more obvious LD-composite anode efforts have
already been tried by amateur chemists.
I believe I do have about a kilo of the correct crystalline LD for this sort of anode. Some very basic experiments showed it to be highly conductive,
and I did some simple experiments using PVC, but nothing to the point of actually setting up a cell.
Question - could the failure of composite amateur LD anodes come from chloride? Were these earlier efforts designed to take chloride to perchlorate?
If so, maybe the answer is to reserve such an anode for chlorate --> perchlorate. Keep Cl- to a minimum, which seems to be the culprit in anode
failure, more often than not.
|
|
|
watson.fawkes
International Hazard
Posts: 2793
Registered: 16-8-2008
Member Is Offline
Mood: No Mood
|
|
Quote: Originally posted by 12332123  | | This would require lower synthesis temperatures and hopefully have lower internal stresses than a ceramic electrode while being longer lasting than a
plated one. |
You could, it seems, use a knit-fiber of PTFE or other appropriately inert material. Think of
the kind of knit that a copper scrubbing pad has. This material would be compressible and provide stress relief, but not have adequate tensile
strength. Therefore, combine this with a related woven or knit material made from titanium wire. The main difference in plating procedure is that it
would have to start off slower, to account for the small cross section of the electrode substrate initially.
All this is hypothetical, but the suggestion of incorporating a compressible material in a composite seems like a good one.
|
|
|
White Yeti
National Hazard
Posts: 816
Registered: 20-7-2011
Location: Asperger's spectrum
Member Is Offline
Mood: delocalized
|
|
The plante999 has already thought of this and it seems like every time I look, someone has an even crazier idea about anodes for chlorate cells.
The quick answer is that if you have an anode made from a binder and lead dioxide particles, you will get regions of very poor electrical conductivity
and high resistance where some particles just so happen to meet. This would cause heating of the electrode and the softening of the binding material,
worsening the situation.
If you paint the PbO2 onto the surface, the thickness of the coat would limit the amount of current the anode can take.
"Ja, Kalzium, das ist alles!" -Otto Loewi
|
|
|
AndersHoveland
Hazard to Other Members, due to repeated speculation and posting of untested highly dangerous procedures!
Posts: 1986
Registered: 2-3-2011
Member Is Offline
Mood: No Mood
|
|
Chromium dioxide ceramic conducts electricity.
|
|
|
White Yeti
National Hazard
Posts: 816
Registered: 20-7-2011
Location: Asperger's spectrum
Member Is Offline
Mood: delocalized
|
|
It might conduct electricity, but does it withstand the corrosive environment in a chlorate cell?
"Ja, Kalzium, das ist alles!" -Otto Loewi
|
|
|
gregkdc1
Harmless
Posts: 5
Registered: 22-10-2011
Member Is Offline
Mood: No Mood
|
|
I was wondering if an anode made out of lead dioxide and silicates would work? I know that calcium hydroxide and more than likely lead hydroxide
reacts with silicate solution to make the hydrated silicate salt. So in theory you could start with a compressed mixture of lead dioxide and lead
hydroxide. When you get this anode wet with sodium silicate solution it should react to make lead silicate hydroxide which is hard like glass. The
only thing I am not sure of is how does lead dioxide react with silicates? Anyways just a thought.
On a side note I keep finding a research article from India about graphite substrate lead dioxide anodes, I am sure you guys have read the same
article. The article talks about electrolyzing NaCl all the way to perchlorate. They say that one of their anodes has been used for over 400 days
and that the lead dioxide layer is 5mm thick. My question is how thick is everybody else making their lead dioxide layer? At 5mm thick I would dare
say that their anode is really a massive lead dioxide anode with a graphite core, and maybe this is necessary to making anode that will last.
Last I was wondering if you made a massive lead dioxide anode could you start out with a big pellet of lead dioxide that you then electrolyze into one
solid piece? This way you could cut down on the time it takes to plate an anode and save plating electrolyte.
|
|
|
dann2
International Hazard
Posts: 1523
Registered: 31-1-2007
Member Is Offline
Mood: No Mood
|
|
Hi Gregkdc1 (thats a ferocious handle),
The mother (or so they say  ) of all guides on Lead Dioxide Anode is here:
http://www.oxidizing.110mb.com/chlorate/leaddiox/leaddioxide...
Graphite substrate Anode have never worked for the average garage maker as you need a PERFECT coating of Lead Dioxide that never seems to
materialize.
Use some MMO (Titanium mesh covered in MMO) as the substrate. Thats the best way to go IMO.
See the last post of this thread:
http://www.sciencemadness.org/talk/viewthread.php?tid=2465&a...
Massive Anode can be made to work but can be troublesome and easy to break.
See US 3,318,794 for a type of Anode that you speak of. I have no idea if it will work. I have me doubts.
Dann2
[Edited on 23-10-2011 by dann2]
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
