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Author: Subject: More on PbO2 electrodes
dann2
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[*] posted on 12-2-2007 at 18:05


Quote:
Originally posted by Rosco Bodine



Are you using the added nickel and copper nitrate in the lead nitrate plating bath when you are plating your
PbO2 onto your carbons ? IIRC you can improvise this
additive by dissolving US nickel coins in nitric acid ,
since they are actually made of a copper and nickel alloy ,
though I don't recall if the proportions are correct .
Also there was a surfactant supposed to be used and
a very specific rate for the plating .

A threaded tantalum rod would make a good substrate
if you have $75 you would like to spend .

http://cgi.ebay.com/TANTALUM-SOLID-ROUND-THREADED-ROD-5-16-2...

[Edited on 12-2-2007 by Rosco Bodine]


I have used Cetyltrimethlyammonium bromide (also called Hexadecyltrimethylammonium bromide), quite a jaw breaker!

Some thoughts on surfactants here:

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

There arel lots of claims made for different surfactants in the journals.

I always use Copper Nitrate. Never used Nickle nitrate.

The idea of the ceramic (or other totally indestructable substrate) substrate was that (hopefully) any old coating of Lead Dioxide would give a workable Anode. This proved not to be the case because of problems of the substrate conducting the salts up to the connections when used in the (Per)Chlorate cell. Also it is difficult to get a good electrical connection to the Anode if the coating is very bad.

I often thought about using Ti sponge (I don't know where to purchase this stuff) as a substrate. The Anode when formed would be treates as a massive Anode. The electrical connection being made to the Lead Dioxide itself. You might end up with problems similar to ceramic substrate though.

Dan
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[*] posted on 12-2-2007 at 20:19


That mouthful sounds like "cepacol"antiseptic mouthwash:D

I'd bet that surfactant spreader-sticker wetting agent which is added to water based sprays of fungicides and fertilizers would also work . I think it is a polyoxyethylene
type and is also a non foaming emulsifier .

I don't think titanium will survive unless it is platinum plated .

And the way in which the PbO2 is deposited , the electrolyte additives , the temperature and current
density are all quite specific to obtaining the adherent
type of PbO2 allotropic modification which has structural
integrity ....just any old PbO2 won't cut it and will always
disintegrate . The PbO2 must have a very specific
crystalline structure . That is what the patents on PbO2
anodes are really all about , the art of growing electrodeposited crystals of a specific sort of PbO2 that is dense and durable . The nickel is important I think ,
and fluoride is used too although I am not certain it is essential .

Attachment: US2945791 GSLD anode.pdf (575kB)
This file has been downloaded 849 times

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hashashan
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[*] posted on 25-3-2007 at 14:03


Well i don't know if thats the best place for it but
i managed to plate PVC with PbO2 using the geocities method. But a weired thing happned
as soon as i started the electrolysis a brown cloud misted the whole vessel. the current is kept on 6A and the voltage is 5V.
Is the cloud something i should worry about or is it there just because the anode is new?
Also can i raise the voltage to 12V, just want to speed up the process, i dont want to wait a month :(


PS. i started my electrolysis from raw NaCl and not chlorate.
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[*] posted on 26-3-2007 at 07:03


Well my electrode failed .. for some reason it cracked swollowed and disintegrated :(
I will try to make the cloth reinforced eletrode today
also ive seen its possible to use titanium as substrate ... how do you do that?
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[*] posted on 30-3-2007 at 13:41


Hello,

Sad to see the Anode fail. What did the coating look like. Was it a fearly good coating? Was it continous and hard?
Are you sure you are using a DC voltage connected the right way around in your Chlorate cell?. A brown cloud forming immediatly almost sounds like you had the Lead Dioxide connected to the minus.

Using Ti is not so simple as far as I can make out. You need a coating of Platinum on the Titanium first or the Anode will fail because Ti Oxide will eventually form between the Lead Dioxide and the Ti metal.

These's Lead Dioxide Anodes have not been so simple as it sound to make. I have always though that there was potential for the 'Cloth substrate' Anodes. I make some of them. I use one of them for about two weeks in a cell untill it got eaten away. It was a very thin Anode. It did not crack or fail suddenly, simply slowly got thinnner which I thought was a good sign. I give some of them to another guy to try out but never heard anything back.
They can be difficult to get the plating to start. You will have to run a small current for quite some time before the 'pasted cloth' will be able to carry a good plating current for to build up the Anode.

Keep us posted.

Dann2
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[*] posted on 1-4-2007 at 02:01


I am currently electrolyzing with a cloth reinforced anode i made.
no signs of erosion at all.
I plated it on scotchbright if there is such a thing where you live. Its a plastic cloth made to rub things in order to clean them.
plated for 3 days on it and now the electrolisys is going well for 3 days already.
however the conection to them is a bitch, i didnt use the silvering method and there is quite a lot of resistance on the conections.
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[*] posted on 1-4-2007 at 16:11


Quote:
Originally posted by hashashan
I am currently electrolyzing with a cloth reinforced anode i made.
no signs of erosion at all.
I plated it on scotchbright if there is such a thing where you live. Its a plastic cloth made to rub things in order to clean them.
plated for 3 days on it and now the electrolisys is going well for 3 days already.
however the conection to them is a bitch, i didnt use the silvering method and there is quite a lot of resistance on the conections.


Nice one!!

I believe the 'cloth' you are using is familar to me.
It is really a matt of plastic, some mm's thick and very porous?
How thick was the cloth (or pasted cloth) when you started to plate?
How thick was it when you were finished plating?
What did you use as a connection to the cloth as you were plating?


Silver is the best by far connection to Lead Dioxide as this article describes.

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

The substrate Anodes have their Graphite or (Pt plated) Ti to do the job.

Any chance of some pictures.
Keep up the good work.

Cheers,
Dann2
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[*] posted on 1-4-2007 at 16:29


Oh dear, I'm answering my own posts!!!!!!!!!

There is silver conductive paint on ebay if you are interested.

http://cgi.ebay.co.uk/Conductive-Silver-Paint-Fix-Repair-Fau...

I used 'silver conductive paint' as the search string.

You should be able to get something similar for mending the heaters on back windscreens of cars in your local car accessory shop.

IF there is alot of heat at the connection the Anode will prematurly fail. IMHO
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[*] posted on 2-4-2007 at 13:10


Well the cloth was about 3mm thick and it didnt get any thicker however it is now fully coated inside its like a single 3mm thick piece of PbO2... very stiff.
the connection at the moment is just a piece of graphite clamped to the end and i manage to get about 5 amps with this conection.
hoever the weired thing that i already electrolized twice the time needed and no perch formed :(
ill continue for a few days and we'll see.
about the pictures the best thing i can do is with my cell phone.
but ill try to upload some good pics if the whole process will be successfull.
i dont know where to get the silver paint and i ddint understand what youve said about the back windscrrens
she shipment to israel of the paint will cost me like a piece of Pt and i just dont see any reason. i want it to be DIY.
for now no signs of corrosion if i wont count the first brown cloud appearing, I think its just because its the first time and some of the coating wasnt good, but bo signs on the electrode itself.
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[*] posted on 2-4-2007 at 16:43


Quote:
Originally posted by hashashan
Well the cloth was about 3mm thick and it didnt get any thicker however it is now fully coated inside its like a single 3mm thick piece of PbO2... very stiff.
the connection at the moment is just a piece of graphite clamped to the end and i manage to get about 5 amps with this conection.
hoever the weired thing that i already electrolized twice the time needed and no perch formed :(
ill continue for a few days and we'll see.
about the pictures the best thing i can do is with my cell phone.
but ill try to upload some good pics if the whole process will be successfull.
i dont know where to get the silver paint and i ddint understand what youve said about the back windscrrens


Hello,

The back windows of cars have a heater in them to stop condensation from forming on the window. The heater can be seen as horizontal lines in the glass. Sometimes one of the lines brake and the heater will not work in the area of that line, giving condensation on the window. Silver conductive paint can be used to repair the line in the glass by simply repainting the line in the window. This silver paint is sometimes supplied by car accessory shops (Automotive factors they are sometimes called over here). The paint contains Silver metal.
Picture of box here:

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


How big is the cell and how much current are you running into it.
Is it NaCl03 or KClO3 you are using.
How do you know that no Perchlorate has formed.
Is your power supply stabalized or is it a more crude device.

Cheers,
Dann2
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[*] posted on 3-4-2007 at 12:10


Quote:
Originally posted by dann2
<snip>
Using Ti is not so simple as far as I can make out. You need a coating of Platinum on the Titanium first or the Anode will fail because Ti Oxide will eventually form between the Lead Dioxide and the Ti metal.

These's Lead Dioxide Anodes have not been so simple as it sound to make. I have always though that there was potential for the 'Cloth substrate' Anodes. I make some of them. I use one of them for about two weeks in a cell untill it got eaten away. It was a very thin Anode. It did not crack or fail suddenly, simply slowly got thinnner which I thought was a good sign. I give some of them to another guy to try out but never heard anything back.
They can be difficult to get the plating to start. You will have to run a small current for quite some time before the 'pasted cloth' will be able to carry a good plating current for to build up the Anode.

Keep us posted.

Dann2


I have had some success with PbO2 Ti anodes. (Do a search for my old posts if you would like to see a picture). I have tried *many* substrates before that (carbon from batteries, pure graphite as well as ceramic) in the distant past but came to the conclusion that Ti is the most suitable.

BTW, the dimensions of the anode in the picture are 5cm x 30cm.

The process that I finally settled upon is a bit laborious but I have had pretty consistent results:

I used Ti sheet of about 1mm thickness because that is waht I had at the time. A little thicker would probably be better.

The first step involves drilling the solid sheet full of small holes. I used a piece of perforated stainless as a drilling guide/pattern. The holes then need to be de-burred or slightly countersunk to get rid of the ragged edges left by the drilling step; I just used a larger diameter drill bit to do this.

The substrate should then be sandblasted, (to help the PbO2 adhere to it. The holes are needed for the same reason) degreased with dishwashing soap, thoroughly rinsed in clean water and dried.

Next, a semiconducting coat of Sb doped SnO2 was applied by painting on a solution of SnCl4 + SbCl3 in water + butanol, drying, and then heating to 500 degrees Celsius or so in an oxidizing atmosphere i.e. air. This step was repeated five to ten times to give a suitable coating thickness. I will try to find the patent that describes this.

Then a thin (about 0.1mm) layer of alpha PbO2 was plated onto the substrate from a alkaline lead tartrate bath. See pat. GB 850,830 for info.

The final coat of beta PbO2 was then plated over top of this from a lead nitrate bath, also described in GG 850,830
This layer was about 2mm thick.

The anode performed well in a perchlorate cell.

-Alembic
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[*] posted on 3-4-2007 at 14:06


Quote:
Originally posted by dann2
Quote:
Originally posted by hashashan
Well the cloth was about 3mm thick and it didnt get any thicker however it is now fully coated inside its like a single 3mm thick piece of PbO2... very stiff.
the connection at the moment is just a piece of graphite clamped to the end and i manage to get about 5 amps with this conection.
hoever the weired thing that i already electrolized twice the time needed and no perch formed :(
ill continue for a few days and we'll see.
about the pictures the best thing i can do is with my cell phone.
but ill try to upload some good pics if the whole process will be successfull.
i dont know where to get the silver paint and i ddint understand what youve said about the back windscrrens


Hello,

The back windows of cars have a heater in them to stop condensation from forming on the window. The heater can be seen as horizontal lines in the glass. Sometimes one of the lines brake and the heater will not work in the area of that line, giving condensation on the window. Silver conductive paint can be used to repair the line in the glass by simply repainting the line in the window. This silver paint is sometimes supplied by car accessory shops (Automotive factors they are sometimes called over here). The paint contains Silver metal.
Picture of box here:

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


How big is the cell and how much current are you running into it.
Is it NaCl03 or KClO3 you are using.
How do you know that no Perchlorate has formed.
Is your power supply stabalized or is it a more crude device.

Cheers,
Dann2


I am running the cell from NaCl and i know that no perch formed because i probed the stuff. I dropped in KCL solution and nothing crystallized.
The cell ran at about 5-12 amps on a PC PSU.
Ill wait a few more days.

BTW, There are a lot of salts climbing up the anode and setteling on the contact. White salts, What are they?
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[*] posted on 3-4-2007 at 14:52


Hello Alembic,

Anode looks good!!

Some holes are visible at the top of the Anode. Are the size and density of theses holes a representation of all the holes that you put into the Ti.

Anode is here:
http://www.sciencemadness.org/talk/viewthread.php?tid=1425&a...

Have you used the Anode for many hours.

Could it be ok if I put your method on a web page.

You sound a lot like a guy I used to communicate with about Lead Dioxide Anodes etc from Canada. His first initial was J.
Perhaps you ARE that guy :)

Will read patent. The two baths sounds like a lot of trouble, but perhaps I am lazy.
Did you ever try coating with Beta (Lead Nitrate bath) only, on top of Sn/Sb coat?
Perhaps you don't give into cutting corners :D

Cheers,
Dann2

Some info on Alpha and Beta Lead Dioxide here:

http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...
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[*] posted on 3-4-2007 at 15:08


Quote:
Originally posted by hashashan






I am running the cell from NaCl and i know that no perch formed because i probed the stuff. I dropped in KCL solution and nothing crystallized.
The cell ran at about 5-12 amps on a PC PSU.
Ill wait a few more days.

BTW, There are a lot of salts climbing up the anode and setteling on the contact. White salts, What are they?


Hello Hashashan,

You are not measuring the current very accurately
:D
I would be very supprised if you do not get Perchlorate eventually. You probably need to run the cell for longer.

The salts will be a mixture of what is in the cell. NaCl, NaClO3, and NaClO4 when it begins to form. (and some KCl too!)

Are the salts climbing up the Anode on the outside of the Anode or are the salts climbing up the Anode in the interior (inside) of the Anode?
If the Anode is porous (not solid) the salts will climb up inside the Anode and will be very hard to stop.
If the salts are simply climbing up the outside of the Anode this is easy to stop by better sealing the Anode into the lid of the cell.

There is a rant about Anode sealing here:

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

Posyester {edit: thats Polyester} resin (purchase in car accessory shop) is great for sealing Anode into lid.

How big is the cell.

Cheers,
Dann2

[Edited on 4-4-2007 by dann2]
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dann2
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[*] posted on 3-4-2007 at 15:51


pat. GB 850,830 for info.


Hello,

I think the patent number is incorrect.

Dann2
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[*] posted on 3-4-2007 at 16:00


Quote:
Originally posted by dann2
pat. GB 850,830 for info.


Hello,

I think the patent number is incorrect.

Dann2


Oops! I guess I'm somewhat dyslexic today! :P The right number is GB850380. Sorry for the confusion.

-Alembic
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[*] posted on 3-4-2007 at 21:46


Quote:
Originally posted by dann2
Quote:
Originally posted by hashashan






I am running the cell from NaCl and i know that no perch formed because i probed the stuff. I dropped in KCL solution and nothing crystallized.
The cell ran at about 5-12 amps on a PC PSU.
Ill wait a few more days.

BTW, There are a lot of salts climbing up the anode and setteling on the contact. White salts, What are they?


Hello Hashashan,

You are not measuring the current very accurately
:D
I would be very supprised if you do not get Perchlorate eventually. You probably need to run the cell for longer.

The salts will be a mixture of what is in the cell. NaCl, NaClO3, and NaClO4 when it begins to form. (and some KCl too!)

Are the salts climbing up the Anode on the outside of the Anode or are the salts climbing up the Anode in the interior (inside) of the Anode?
If the Anode is porous (not solid) the salts will climb up inside the Anode and will be very hard to stop.
If the salts are simply climbing up the outside of the Anode this is easy to stop by better sealing the Anode into the lid of the cell.

There is a rant about Anode sealing here:

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

Posyester resin (purchase in car accessory shop) is great for sealing Anode into lid.

How big is the cell.

Cheers,
Dann2

The anode is quite small about 4*6 cm, the cell is a 2 mole sell.
And i know im not measuring the current very acurately , thats because the cerll is just experimental to check if the anode will last at all.
The salts are from the outside.
Today a weired thing happned, a chunk of the anode just got eaten away and the curent dropped to 0.6 A,
I rewired the whole thing and now the cell is running at about 3-4 amps(quite a drop)
does the current drop when the NaCl is getting low?
does the current drop at any stage?
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[*] posted on 4-4-2007 at 03:34


Quote:
Originally posted by dann2
Hello Alembic,

Anode looks good!!

Some holes are visible at the top of the Anode. Are the size and density of theses holes a representation of all the holes that you put into the Ti.

Anode is here:
http://www.sciencemadness.org/talk/viewthread.php?tid=1425&a...

Have you used the Anode for many hours.

Could it be ok if I put your method on a web page.

You sound a lot like a guy I used to communicate with about Lead Dioxide Anodes etc from Canada. His first initial was J.
Perhaps you ARE that guy :)

Will read patent. The two baths sounds like a lot of trouble, but perhaps I am lazy.
Did you ever try coating with Beta (Lead Nitrate bath) only, on top of Sn/Sb coat?
Perhaps you don't give into cutting corners :D

Cheers,
Dann2

Some info on Alpha and Beta Lead Dioxide here:

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


The holes were about 2.5mm and yes, you can get some idea of the density of those holes from the picture.

That specific anode was only used for two batches of perchlorate, starting from NaClO3, which means that is has seen about 200 hours of use at a current of 35-40 A. It still looks pretty much exactly the same. I have made other anodes (using the same process) that I've used in chlorate cells for hundreds of hours with no visible signs of wear.

You can put my method on your web page if you want. I'm also pretty sure we've communicated before since I just happen to be from Canada and my first initial also happens to be J. ;)

The alpha PbO2 layer was added in order to improve adhesion + uniformity of the final beta PbO2 layer. See US5683567 for a description of a very similar anode.

I used to always try and cut corners but after accumulating a whole lot of hazardous waste from failed attempts I've come to realize that it is easier to do it properly, even if it is more work.

-Alembic
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[*] posted on 4-4-2007 at 14:19


Quote:



The anode is quite small about 4*6 cm, the cell is a 2 mole sell.
And i know im not measuring the current very acurately , thats because the cerll is just experimental to check if the anode will last at all.
The salts are from the outside.
Today a weired thing happned, a chunk of the anode just got eaten away and the curent dropped to 0.6 A,
I rewired the whole thing and now the cell is running at about 3-4 amps(quite a drop)
does the current drop when the NaCl is getting low?
does the current drop at any stage?


It would be near impossible if not totally impossible to tell the concentration of NaCl in the cell by observing what the current is. IMHO
The Voltage accross Perchlorate cells is generally higher in industry but the main reason why the Voltage is higher is because the Anodes are driven at a higher current density and the cells usually have a lower volume to current ratio when compared to Chlorate cells. The higher current densities and the lower volume to current ratio are decisions made by the manufacturers for economic reasons that don't really concern the home Perhlorate maker.
Higher current densitys and lower volume to current ratio are NOT essential (when compared to Chlorate cells) when making Perchlorate. If you were going to make a few tons per day then it would be very very wise to have cells running at high current densitys etc for economic reasons.

I do not think that the current will drop any significant amount at any stage during the manufacture of Chlorate .....to ....Perchlorate.
It would be an interesting experiment to put an accurate current meter into the circuit, using a voltage stabalized supply (Computer supply would be good) and logging/observing how the current varies as the process proceeded. You would need to keep the cell temperature and the level of electrolite steady.

Cheers,

Dann2
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[*] posted on 4-4-2007 at 14:38


Quote:
Originally posted by Alembic

The alpha PbO2 layer was added in order to improve adhesion + uniformity of the final beta PbO2 layer. See US5683567 for a description of a very similar anode.

I used to always try and cut corners but after accumulating a whole lot of hazardous waste from failed attempts I've come to realize that it is easier to do it properly, even if it is more work.

-Alembic


Hello Alembic,

The whole "Lead Dioxide Anode thing" is littered with noble but failed attemps at getting long lasting anodes that can be made at the back of a ditch (as we say over here), for next to nothing, with hardware store chemicals :)
The proper way seems to be the only way!

I am experimenting with a Magnetite Anode at the moment. The current effeciency seems to be HOPELESSY low.

Do you recognise this. You wrote method one :-)

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

It's good to meet and hear from you again. You were always a DAMM GOOD source of information and conversation.

Cheers,
Dann2 (formerly Dann1..... formerly..........)
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[*] posted on 5-4-2007 at 00:31
Bismuth modified , erosion resistant PbO2


This could be useful information , and I don't recall seeing it posted before . Evidently the co-plating of a controlled amount of bismuth peroxide with lead peroxide forms a
harder and denser , much more erosion resistant PbO2
anode which also operates at better current efficiency .
This is only useful in a limited thickness because cracking problems develop with heavier layers . It might be possible to build up a thicker anode using cloth wrap or intermediate layer reenforcement as was mentioned earlier in this thread .

The patent also describes an interesting improvised flow through coaxial electrode which was used for one of the experiments , where the electrolyte is pumped through
the electrode assembly .

[Edited on 5-4-2007 by Rosco Bodine]

Attachment: US4101390 Bismuth modified thin layer Lead Dioxide Perchlorate Anode.pdf (977kB)
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[*] posted on 5-4-2007 at 19:58


hehe ,i am from china
i first in it ..
my please
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[*] posted on 7-4-2007 at 05:00


dann, i couldn't find any silver paint for a good price since i missed that ebay bid.
So i am looking for other methods.
Can silver be electrodeposited on the PbO2 anode? and how should it be done?
Are there other metals that can be electrodeposited on it (not Pt).
How about a good graphite connection, is it possible? maybe grapite coated with PbO2, it wont be immersed into the electrolyte so it wouldn't corrode away, am i right?
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[*] posted on 7-4-2007 at 09:31


Hello Hashashan,

You could try very Silver powder mixed with a solvent. Or silver wire wrapped around the anode. You will find a link to Silver plating here:

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


Below is more silver paint on ebay. It will cost a lot less that starting to electroplate silver.



http://search.ebay.co.uk/search/search.dll?from=R40&sati...
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dann2
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[*] posted on 7-4-2007 at 10:15


Quote:
Originally posted by Rosco Bodine
This could be useful information , and I don't recall seeing it posted before . Evidently the co-plating of a controlled amount of bismuth peroxide with lead peroxide forms a
harder and denser , much more erosion resistant PbO2
anode which also operates at better current efficiency .
This is only useful in a limited thickness because cracking problems develop with heavier layers . It might be possible to build up a thicker anode using cloth wrap or intermediate layer reenforcement as was mentioned earlier in this thread .

The patent also describes an interesting improvised flow through coaxial electrode which was used for one of the experiments , where the electrolyte is pumped through
the electrode assembly .

[Edited on 5-4-2007 by Rosco Bodine]


Hello,

It is interesting to note that they only mention in the patent (page 6 lines 10 to 15) very brifely that it may be needed to coat the substrate with Pt or some of its oxides. You would think they were trying to hide the fact................

Cheers,

Dann2
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