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dann2
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| Quote: | Originally posted by hashashan
the solution was neutral and some lead nitrate started to crystallize out, that why i say it was saturated.
the problem was that i mixed it with another solution that was pretty acidic (found out after the addition) it was about PH 1-2 maybe that was the
reason that all the PbO2 that was sprinkled on the plastic and fabric was dissolved? or there might be another reason? |
Perhaps you bath is contaminated with something. Some of the patents give contaminates that were bad news. Chloride was one of them. Iron also.
If you can get a small piece of graphite (not a gouging rod) and see if it will plate ok.
Are you using high grade chemicals to make up the bath or is the Lead Nitrate (and carbonates, or hydroxides or litharge) homemade.
What type of water are you using, tap or distilled. You may have contaminates in the water.
I used to test my tank using a piece of graphite to see if it would plate ok before I tried a more 'exotic' substrate. If it will not plate
graphite, and the Lead Ion and Nitric acid concentrations are within acceptable limits then the bath must be contaminated with something.
What temperature are you using. If the temperature is too low I would think the bath will not plate properly.
Dann2
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hashashan
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well ill try to maintain better conditions.
just that i used that solution already to make an anode, only added more nitrate to it thats it.
well ill do my best again
thanks
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Rosco Bodine
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Just offering a thought concerning pH control and lead content replenishment in the electrolyte from which PbO2 is being plated .
Lead forms basic salts which are less than half the solubility of the normal salts in plain water , and likely
even less soluble in solutions already concentrated
with respect to the normal salt .
It would seem there are a couple of ways that this could be exploited , depending upon the accuracy demanded for
the particular plating process . It may be adequate to
simply bundle some of the basic nitrate in a piece of cloth
gathered into a ball , and use it like a teabag in the
electrolyte . There should be a solubility equilibrium where
the presence of the solid undissolved basic salt in contact with a solution of the normal salt would function as a buffer to automatically maintain
the composition of the electrloyte constant , with regards to both pH and concentration of Pb ion . As the electrlolyte became more
acid because of lead plating out , the acidity would react
with the basic salt converting it to the normal salt which would enter solution to maintain the equilibrium .
A mechanically controlled method could be used also to
maintain the equilibrium or any desired composition at any point away from equilibrium .
A heating tape could be used to keep a graduated addition funnel warm so that a relatively saturated solution of the basic salt could be kept
available for metered dropwise addition at a rate calculated to match the lead deposition rate as a function of current efficiency , and measured
current . This would
be a relatively precise method also .
There are a series of basic salts associated with the acetate , one or all of which could be useful if acetate
is tolerable or desired in the particular plating bath .
And there is one basic nitrate of lead which should also
be workable in either of the schemes for keeping the
electrolyte composition constant . IMO these methods
could have advantages over the use of carbonate ,
primarily that no microbubbles of CO2 would be introduced into the solution as a byproduct which could
roughen the surface plating , and that the handling
of soluble basic salts is otherwise more convenient for
metering precisely during additions , than is the manipulation involving additions of a solid carbonate ....
which just seems to be a poorer source of lead ion to
be added to a sensitive reaction system .
[Edited on 9-5-2007 by Rosco Bodine]
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hashashan
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Guys anyone tried to make perch from NaCl directly with PbO2? its the second time i get crappy results.
What happens when i electrolyze above 6V, i do it @ 12V 10A with anode surface about 40cm^2. when i did this from chlorate everything went swiftly,
but from NaCl when i try to make a probe crystallization with KCl all i get is a white cloudy substance and not even the chlorate crystals, any
thoughts on that?
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12AX7
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KClO4 is rather insoluble and would tend to make a flocculent precipitate, especially if the KCl is concentrated. The only other possiblity is PbCl2,
but that would require the solution to be initially acidic and reducing (something which would dissolve the PbO2).
Filter and recrystallize.
Tim
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dann2
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| Quote: | Originally posted by hashashan
Guys anyone tried to make perch from NaCl directly with PbO2? its the second time i get crappy results.
What happens when i electrolyze above 6V, i do it @ 12V 10A with anode surface about 40cm^2. when i did this from chlorate everything went swiftly,
but from NaCl when i try to make a probe crystallization with KCl all i get is a white cloudy substance and not even the chlorate crystals, any
thoughts on that? |
Hello,
How many grams Chloride was in the cell at start?
How many ml's solution did you have?
How many amper hours did you run into the cell?
It is not the voltage that you are applying to the cell that
gives the conditions for Perchlorate formation.
If you get an immediate cloudy ppt with KCl then that is Perchlorate precipitating. The KCl is a relatively crude test.
Cheers,
Dann2
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hashashan
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Well i didnt wait enough for the crystalisation, i do have some chlorate but still no perchlorte(which is ok).
I am running a cell :
Volume : 1 liter
NaCl : 350gr
Amps : 10
AH : about 1000
However the cloudy ppt isnt perch, it remained even after i boiled the solution with sulfite in order to check for perchlorate. its some kind of a
fluffy cloudy ppt, looks alot like the residue of a very concentrated KOH solution upon cooling.
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dann2
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| Quote: | Originally posted by hashashan
Well i didnt wait enough for the crystalisation, i do have some chlorate but still no perchlorte(which is ok).
I am running a cell :
Volume : 1 liter
NaCl : 350gr
Amps : 10
AH : about 1000
However the cloudy ppt isnt perch, it remained even after i boiled the solution with sulfite in order to check for perchlorate. its some kind of a
fluffy cloudy ppt, looks alot like the residue of a very concentrated KOH solution upon cooling. |
I calculate the 'run time' of the cell to be about 5.7 days.
This 'run time' assums the cell is finished when concentration of Chloride is at 100 grams per liter. To get Perchlorate to start to form you would
need to run for at least 6 days on top of this (guessing).
I am using the program at the bottom of this page to calculate the time to get to 100grams/liter.
edit: to get down to 100g/l chloride
http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...
What sort of cathodes are you using
Cheers,
DANN2
[Edited on 12-5-2007 by dann2]
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dann2
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Hello,
I was redissolving some Na Chlorate (contained some Chloride, no Perchlorate) after one crystallization from
cell liquid and when I added water I too got a ppt
floating about in the water that will not dissolve.
Heating makes no difference.
Adding acid
makes it dissapear as I tried it on a small quantity.
I do not know what the PPT is.
Dann2
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dann2
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| Quote: | Originally posted by dann2
Hello,
I was redissolving some Na Chlorate (contained some Chloride, no Perchlorate) after one crystallization from
cell liquid and when I added water I too got a ppt
floating about in the water that will not dissolve.
Heating makes no difference.
Adding acid
makes it dissapear as I tried it on a small quantity.
I do not know what the PPT is.
Dann2 |
After boiling the above solution and concentrating, the PPT appeared to turn a brown colour. Then it dissapeared on cooling. I thing the Chorate, as
it crystallized, removed the ppt from the solution. It is physically incorporated into the Chlorate crystals (this is just a guess)
Is boiling Chlorate solutions compatable with borosilicate glass.
For examply, boiling NaOH solution is not, would the Chlorate be attacking the glass?
(or is it just Lead making me paranoid)
Dann2
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12AX7
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Hell, chlorate is compatible with iron, I've boiled solution in tin cans many times. Hypochlorite is nasty on steel, but chlorate is fine.
Tim
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hashashan
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| Quote: | Originally posted by dann2
| Quote: | Originally posted by hashashan
Well i didnt wait enough for the crystalisation, i do have some chlorate but still no perchlorte(which is ok).
I am running a cell :
Volume : 1 liter
NaCl : 350gr
Amps : 10
AH : about 1000
However the cloudy ppt isnt perch, it remained even after i boiled the solution with sulfite in order to check for perchlorate. its some kind of a
fluffy cloudy ppt, looks alot like the residue of a very concentrated KOH solution upon cooling. |
I calculate the 'run time' of the cell to be about 5.7 days.
This 'run time' assums the cell is finished when concentration of Chloride is at 100 grams per liter. To get Perchlorate to start to form you would
need to run for at least 6 days on top of this (guessing).
I am using the program at the bottom of this page to calculate the time to get to 100grams/liter.
edit: to get down to 100g/l chloride
http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...
What sort of cathodes are you using
Cheers,
DANN2
[Edited on 12-5-2007 by dann2] |
when you say 6 days on top of that what exactly do you mean? on top of the 5 days or just 6 days?
the cathode is a gauging rod, i have put there several but decided to use only one (the distance between the anode and cathode is about 8cm) because
when i used more then one the current was way to high.
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Rosco Bodine
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an idea similar to the cloth reenforced GSLD
On page 7 of this thread a patent US4236978 was posted by me , in connection with an idea of spiral wrapping a
graphite substrate with stator lacing tape , which I thought
might produce a similar effect as described in the patent .
I have been thinking some more about this and have another
related idea , which involves actually cutting a thread on the
graphite rod , and then wrapping a spiral of polyester filter
yarn directly into the grooves of the thread . Possibly a second spiral wind of yarn could be laid down in the same
direction , between the windings of the first spiral , to completely cover the peaks of the threaded graphite .
But such a second spiral may not even be necesssary .
The polyester filter yarn could be wound at a controlled tension using the same technique as used for winding wire
on a magnet coil , the precision drag on a Penn deep sea
fishing reel at a minimal setting , if you have one would work great for this .
Anyway , if the claims of the patent are accurate , then having a suitable polyester substrate at the interface between graphite and lead dioxide
which is being plated ,
greatly reduces the complexity of the electrolyte required for
producing a superior anode , and widens the window considerably for the conditions that are needed for producing
a high quality PbO2 anode .....so the plating process is more forgiving of an improvised setup , where more exotic electrolyte mixtures and close
control of the process is
difficult or impossible .
Many of the patents concerning various improvements move things towards greater complexity , using extra steps and
electrolyte additive ingredients , and carefully controlled conditions to achieve better results , but US4236978 seems
to be the only one which *simplifies* things for a GSLD type
of anode .
I don't know if the spiral wrapped polyester filter yarn will
work , but it is OTC in water filter cartridges and it seems worth a try as a winding . I am not sure if the brittleness
of a gouging rod , or a high density graphite rod will permit
threading to be cut using an ordinary threading die . An
Acme thread with a very progressive and gently tapered cut
in a deeper die , something like a coupling sleeve nut which has been reamed , throated , and slotted down its length in the middle of a flat might
have to be made if the graphite is too brittle for a standard threading die .
IIRC , I have used a brass nut as a connection for the top of round graphite rods , by cutting a couple of internal slots
lengthwise across the threads in the nut using a needle file ,
and then hand threading the nut which was made into an
improvised thread cutting die , onto the graphite rod and
then soldering a ring terminal to it . But that would have been thirty years ago , so I can't swear to it .
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Eclectic
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It would be much simpler to cut large external threads in graphite in a lathe. I might give it a try, but I like the SnSb oxide on titanium better.
I think there will always be a problem with the PbO2 oxidizing the graphite surface and causing high resistance over time.
Dip and bake SnSbO2 on graphite first? Should be easy to test with 95/5 solder dissolved in HCl/peroxide solution.
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dann2
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| Quote: | Originally posted by hashashan
when you say 6 days on top of that what exactly do you mean? on top of the 5 days or just 6 days?
the cathode is a gauging rod, i have put there several but decided to use only one (the distance between the anode and cathode is about 8cm) because
when i used more then one the current was way to high. |
I meant that you will need to run for another 6 days after you have run the cell for 5 days. (11 days total). The 6 days are a guess because it is
very hard to know when the Chloride concentration will get down to (about) 10% and Perchlorate will start to form.
In fact the 5 days is a guess too because we are guessing the current efficiency to be about 50%.
A guy told me (on the blog of the geocities page) that he was able to purchase Methylene blue in a pet shop. It is useful to have for testing for
Perchlorate.
It is for sale on ebay too.
Cheers,
Dann2
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Rosco Bodine
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@Eclectic
Often I have wondered if there is an electrical differential
across the interface between the graphite and the PbO2
which is aggravated when the contact is made to the graphite alone , when the anode is in service in the perchlorate cell . It may increase the
service life of the anode to make the connection to the PbO2 with a silver
contact , perhaps also connect to the graphite substrate
so that any IR voltage drop between the two is nullified .
Of course a lathe is nice if you have one , and you could even use a rotary bur as your cutting tool for chasing the thread .....but none of that is
simpler than rotating the rod by hand through a thread cutting die , if that can be
done easily enough . It wasn't special large threads I was thinking about , but standard 1/2" X 13 TPI coarse thread .
The whole idea of a polyester intermediate substrate is to get away from needing exotic pre-treatments
for the graphite , exotic electrolytes , surfactants which degrade and contaminate the PbO2 plating bath .
Any of the exotic refinements can be utilized additionally with no harm done , perhaps to improve the anode further if desired . However if a
simpler and more easily made anode can last for months in service , then why bother with the extra trouble , but just make several of the simpler
anodes ...replacing them when necessary ?
Has anyone tried mirroring or plating free metallic silver onto graphite as an interface between graphite and PbO2 ? It should oxidize in situ to
silver oxide which is highly conductive . Or for the baking of chlorides scheme how about using the combination of silver doped tin , as there are
also lead free soft silver solders that are 96%Sn and 4%Ag .
[Edited on 13-5-2007 by Rosco Bodine]
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dann2
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Hello,
Thanks for patent. Will read up on it.
As far as Graphite is concerned I have lost all faith in it as a substrate as I think that (cloth/twine/rope wrap or bare) if you do not have a high
quality coating of Lead Dioxide the (Per)Chlorates will 'get at' the Graphite and ruin the Anode.
Perhaps I am wrong.
I have read and been told about lots of (seemingly perfect) Graphite substrate anodes that fail soon after they are put to work.
I have make GSLD anodes myself that have looked *perfect* and they failed within hours of being put into a Chlorate cell. Perhaps I am a bit
Anti-Graphite at this stage.
Only one guy I spoke to has made and used a GSLD (He would have use a fairly good set up).
He has since changed to Ti substrate though.
As far as Gouging rods are concerned my opinion is that they should be avoided like the plague. They are a very inconsistent product. They vary from
manufacturer to manufacturer and from type to type. A guy (hello Allen!!) told me that there was Iron (or perhaps some other metal) in gouging rods
that he had. Iron is bad news in a Lead Dioxide plating tank. They are OK for Cahthodes in Chlorate cells but not OK for Cathodes in Lead Dioxide
plating tank(as they may have Iron particles in them).
At the very least use EDM (Electro Discharge Machine) Graphite.
Graphite is easy to put threads on using a simple treading nut from engineering supply store.
Has anyone else tried the 'Gilbert Pinkston Anode'.
http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...
It sounds like the ultimate in simplicity.
Cheers,
Dann2
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Rosco Bodine
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The *fact* is that graphite alone or even gouging rods alone can be used as anodes in a perchlorate cell , even without any PbO2 to improve their
erosion limited life ,
which is more than a few hours , if the current density
is optimum . IIRC it was Mad Hatter who provided some
first hand data on this . So I am a bit doubtful concerning the dismissing of graphite as a substrate for PbO2 ,
given the numerous patents and commercial use .
Anyway I do have some EDM graphite in transit , and it is nice to know that it will thread okay ....I was thinking
it should cut like teflon , being self lubricating , about like
threading a candle stick  , not quite as easy as cutting butter , but not too
far from it , so long as the stuff didn't chip . I had a concern it might go snap crackle pop and
then wring the whole rod in two from any herky jerky little jolts and grabs as it is cutting . Another reason I
wanted to cut the thread by hand . Graphite is brittle ,
drop a piece on the concrete floor and it will break .
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12AX7
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Heh actually I've dropped my graphite crucible (carved from a block of the stuff) on the floor from a few feet up and quenched it in water from orange
heat. The only thing that it isn't particularly resistant to is oxygen...
Tim
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Eclectic
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Oh, I thought you were going to try 2-3" rod. 1/2" EDM graphite should be fine to thread by hand with a die. I have some 2" furnace electrodes that
are like compressed charcoal, and would be iffy to thread even in a lathe.
I think silver and silver oxide dissolve readily in chlorate cells, while the SnO2 treatment seems to hold up for 600+ hours on Ti. I'm just thinking
of it as a quickly applied coating on the graphite to avoid the "Dragon's Egg" composition PbO2/C interface.
Could someone do a quick check of 95/5 solder as a chlorate cell anode? (It CAN'T be THAT simple...)
[Edited on 5-13-2007 by Eclectic]
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Rosco Bodine
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Are you sure about dragons eggs being a reaction between carbon and PbO2 ? I was thinking that was something else ,
like an intermetallic reaction ...not carbon . Anyway that is a high temperature effect and I'm not sure it has a lower temperature much slower
reaction parallel .
I didn't know there was any particular chemical interactivity between PbO2 and carbon at low temperature , and I was thinking that the oxidizing
effect of PbO2 was not any real problem with graphite , but rather a physical separation , flaking off due to cracking or permeation of the
electrolyte causing a physical delamination like water seeping between two polished sheets of glass .
Anyway , in another earlier patent US4101390 which I posted on page 8 I think , about the use of a bismuth oxide modified PbO2 finish layer being more
erosion resistant , the patent stated that the initial PbO2 to graphite adhesion was best using PbO2 alone directly to graphite alone . I don't
recall any patents referencing a need for any preliminary plating of the graphite with anything other than PbO2 , though some did speak of the need
for special surface preparations like sanding the graphite with coarse sandpaper to roughen up the surface for better adhesion .
And in none of the graphite anode patents have I ever seen any problem described concerning graphite to PbO2 interface having electrical connectivity
problems , except the
obvious connection loss when PbO2 layer cracks and
detaches , exposing the graphite to erosion . That bismuth oxide related patent also described an interrupted plating procedure , where a first layer
of pure PbO2 was applied as a " primer " to the graphite , followed by transferring the electrode assembly to a separate plating solution containing
bismuth nitrate along with lead nitrate , to plate a more erosion resistant
" finish layer " of bismuth adulterated PbO2 . That patent
also said it was best to begin the plating of the primer
layer of pure PbO2 in a low acidity high Pb content electrolyte at high current density , and as the plating got
heavier and the acidity increased and the PbO2 content
decreased to ramp the current density lower , particularly in the second phase .
I believe there are probably useful bits of information which can be gleaned from several patents , and combined to good effect at simplifying the
process and improving the results .
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Eclectic
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No, I was just thinking out loud. Strong oxidizer in intimate contact with carbon with lots of current crossing the interface seems like it might
contribute to loss of adhesion...
I'm all for lots of experimentation. (And making known the results)
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12AX7
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I've heard that certain tantalum capacitors are rather nasty exploders. Reason being the Ta metal in contact with the MnO2 anode in dry types.
Obviously, a dielectric layer of Ta2O5 seperates them, but if it somehow doesn't, and a lot of heat gets generated...(pop!)
Tim
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Rosco Bodine
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Check this out to see the kind of filter yarn I was
talking about , it is actually polypropylene fiber which
is probably even better than polyester . The patent mentions polypropylene fiber as one that works .
http://cgi.ebay.com/String-Wound-Sediment-Filters-10-x2-5_W0...
[Edited on 13-5-2007 by Rosco Bodine]
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dann2
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Carbon for Perchlorate
| Quote: | Originally posted by Rosco Bodine
The *fact* is that graphite alone or even gouging rods alone can be used as anodes in a perchlorate cell , even without any PbO2 to improve their
erosion limited life ,
which is more than a few hours , if the current density
is optimum . IIRC it was Mad Hatter who provided some
first hand data on this . So I am a bit doubtful concerning the dismissing of graphite as a substrate for PbO2 ,
given the numerous patents and commercial use .
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Edit: One square bracket added
I need to learn to use the preview button.
Graphite will make Perchlorate I agree. It is the wear rate that is (allegedely) the problem.
The report by MadHatter is here:
http://www.sciencemadness.org/talk/viewthread.php?tid=5050&a...
posted on 18-2-2006 at 06:53 PM
It reports low erosion rates.
The temperature of the cell is below 40C. (up to 40C)
That is a high temperature for graphite.
I don't know why he started his cell run at 9% Chloride.
Perhaps that is simply the mixture he happened to have and was not prepared to lower the Chloride concentration more by recrystallizing the Chlorate
again (and again).
0% Chloride would be the best start but it is difficult (lot of work) to get homemade Chlorate with 0% Chloride in it.
Quote:-------------------------------
A little NaCl is mixed in because oxidation
of NaCl is more efficient than KCl.
End of quote-----------------------------
Why would Chloride be added to a Perchlorate cell??
Surely only Chlorate is wanted. Perhaps it's a typo.
Quote(From a few posts later)-------------------------------
I like to have .2 amps per square centimeter on the anode. That's about 7 amps on a 3/8"
by 12" gouging rod. I keep the voltage at 6.
End of Quote-------------------------------------
That's an incredible high current density for Graphite. It
is up and kicking with Lead Dioxide.
Also there is a problem with the current density/current into gouging rod. The surface area of the gouging rod (0.9525 cm diameter by 27cm long
(usable lenght)) is 80.8cm squared.
At 0.2 amps per cm squared that would be a current into rod of 16 amps, not 7 (as stated). [hope math is correct]
When the rod wears a bit and gets thinner the current density will go even higher if current is kept constant.
MadHatter also produced 8lbs of Perchlorate using 6 gouging rods. That is a very impressive wear rate. (More than one pound of Perchlorate using one
gouging rod.)
I have heard of people wearing more carbon making Chlorate.
If Carbon is that good it is a wonder why anyone (myself included) would bother with Lead Dioxide, Pt, etc etc.
There is some journal articles refs regarding Perchlorate making using Graphite at this page (at bottom):
http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...
Sihvonen, G., Suomen Kemistilehti, 10B, 27 (1937)
and
Ullman, Frits, "Enzyklopadie der technischen Chemie", Vol. 3, p 299-307, Berlin, Urban & Schwarzenberg, 1929
Anyone got access to them?
DANN2
[Edited on 16-5-2007 by dann2]
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