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Author: Subject: What about silicon as an anode in a chlorate cell?
jpsmith123
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[*] posted on 8-7-2005 at 01:59


Hello 12AX7,

Being that I haven't had a chance to try making any anodes yet, I can't say how critical the conditions are for the anodizing method I found, but I would be surprised if things like temperature, concentration of acid, current density, etc. didn't affect the quality of the results.

With regard to your theory that the "contact resistance" between Pb and PbO2 may be high, I'm wondering what would happen if you change your method of making electrical contact? IOW what if you somwhow clamp to the outside of the PbO2, rather than rely on the Pb-PbO2 interface to conduct current?

Lastly, with regard to plating PbO2 from a lead salt, check out the link below. That guy just used copper for the cathode and he apparently had no problems, but he was using lead nitrate.

Regards,
Joe

http://www.satollo.com/en/chemistry/csld-ceramic-substrate-l...
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12AX7
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[*] posted on 8-7-2005 at 02:38


I doubt the PbO2 is in wide flakes, it's just generally loose stuff.

So the technique is just amps and Pb(NO3)2? Why doesn't this plate Pb?

Tim




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jpsmith123
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[*] posted on 8-7-2005 at 16:19


Strictly speaking, maybe it does actually plate lead first, and then the lead is immediately oxidized? I don't know.
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[*] posted on 10-7-2005 at 22:17
Another Idea


Taking the plastic substrate idea one step further, I wonder if the anode could be made of epoxy mixed with powdered PbO2, and either used like that or with a subsequently plated PbO2 coating?
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12AX7
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[*] posted on 11-7-2005 at 02:45


Or for that matter, get a paint base and fill it to 90% PbO2 like conductive Al/Zn paint. I seem to remember linseed oil is already quite popular with electrode builders.. :)

Tim




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unionised
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[*] posted on 11-7-2005 at 04:48


I wonder if I should start a new thread for this and call it "anything but silicon as an electrode, mainly dealing with PbO2".
Anyway what I did, with a view to at least starting to answer the question that this thread is about, was to use a lump of silicon as the anode in a cell with salt water as the electrolyte and a platinum casthode.
Result; a distinct smell of chlorine. I'm suprised, I would have expected the silicon to be atacked.
Of course, that's not the whole story, you would need to run a real chlorate cell with the stuff to prove the point.
Amazing what a little experiment can do.

Unfortunately, as it's buried at the end of a whole bunch of stuff about lead anodes, I don't supose anyone will ever find this data unless people decide to delete or move their off-topic postings.:mad:

And I don't care that half of the off-topic posts are by the original author.

[Edited on 11-7-2005 by unionised]
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12AX7
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[*] posted on 11-7-2005 at 05:25


Quote:
Originally posted by unionised
And I don't care that half of the off-topic posts are by the original author.


Thread drift stimulates the mind. Something wrong with that? :D

Tim




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jpsmith123
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[*] posted on 11-7-2005 at 05:44


Unionised:

Sorry that the discussion has wandered.
It seems that there are already so many chlorate/perchlorate cell related discussions here, I hesitated to start yet another. (Moreover, I'm new here and I'm still learning the rules).

Should I start another discussion regarding PbO2 anodes?

In any case, with regard to your experiment, may I ask, what kind of silicon did you use?

Lastly, with regard to chlorine, I guess your experiment shows that chlorine won't attack silicon in an aqueous environment?

12AX7:

I just now saw the following paper for the first time:

http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...

The "contact resistance" thing might be one reason people seem to have so much trouble with PbO2.
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[*] posted on 11-7-2005 at 10:15


Hi
I guess I get overly annoyed about people going off topic. Anyway, I'm afraid I can't say much about the Si. It was a lump I got in with some stuff I got from ebay.
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[*] posted on 11-7-2005 at 11:21


There's no need to start a new thread on PbO<sub>2</sub> electrodes; there's already a long one on the subject.
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