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12AX7
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Where is your post/did you even write anything outside of that quote box!?
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dann2
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| Quote: | Originally posted by 12AX7
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 |
Hello Tim,
I think the Ta capacitors (they have a polarity) explode when you connect them the wrong way around.
Perhaps there are not porarized types nowadays (its been a long time since..............)
Cheers,
Dann2
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jpsmith123
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Dann2 have you looked at Beer's patents?
Beer had several patents regarding MMO anodes.
I'll attach one of these patents that has several interesting examples:
Example II involves a graphite substrate for a MMO coating.
Example XVI involves electrolysis to apply the MMO coating.
Example XVII apparently doesn't involve any platinum group metal oxide.
Attachment: 3632498_OCR.pdf (728kB)
This file has been downloaded 1180 times
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dann2
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Thanks for patent.
MMO is Chlorate only.
I have been running an MMO (CORROSION CONTROL WIRE)
anode for about 3 weeks in a cell in an attempt to make Perchlorate.
Ir oxide and Ta oxide I believe. The cell is almost pure Chlorate, just some Chloride.
No Perchlorate has formed.
Dann2
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12AX7
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What's the poop, is it making oxygen instead?
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dann2
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Attempt to make Perchlorate with MMO (DSA) anode
Hello,
I presume it is making Oxygen at the Anode and Hydrogen at the cathode. There comes lots of gas from both electrodes.
The black coating was removes on some of the surface of the Anode. (Anode is black when new.) Black coating that was not removed was just sitting
there, it could be wiped off with a slight rub of a cloth. There is still an active coat on the anode though as it still emits gas when in a cell.
Anode is similar to www.lida.com wire anti corrosion anode.
Edit: Should be www.lidaproducts.com
Cheers,
Dann2
ps. what does poop mean?
[Edited on 26-5-2007 by dann2]
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hashashan
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Some more questions about a good connection.
Any ideas of how to plate silver on the anode without the rochelle salt?
no electro deposition available?
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Esucll
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Ok guys this is my first post in this forum..
PbO2 electrodes aren't the same rods consisting the core of commercial AA or AAA batteries?
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dann2
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The core of theses batteries is Graphite.
You can use it to make Chlorates (and perchlorate with more wear)
Some info here:
www.geocities.com/kkwolly
Dann2
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alancj
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| Quote: | Originally posted by hashashan
Some more questions about a good connection.
Any ideas of how to plate silver on the anode without the rochelle salt?
no electro deposition available? |
I don't know... but Rochelle salt isn't hard to make. Just neutralize cream of tartar (potassium hydrogen tartrate) with sodium carbonate. Filter any
insolubles and then you've got your Rochelle salt (potassium sodium tartrate). You can then recrystallize the salt for increased purity.
The only other electroplating baths for silver use cyanide, which nobody is going to sell to you... which means making it... and I don't know if that
can even be used to plate on PbO2. There is a thread on making cyanides btw.
-Alan
[Edited on 26-5-2007 by alancj]
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hashashan
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cyanides are off the topic ... the lead is enough hazard for me.
I know thte rochelle salt is easy, but i dont have any tartarates, yes i can buy them. However i prefer not to.
The interesting question is why is it problematic to plate silver on PbO2? will it disintegrade if it used as a cathode? what if ill first color it
with the silver paint?
i just want to be able to solder a wire to it.
maybe silver paint and then electroplate copper?
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alancj
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Gee... don't you like the smell of HCN in the morning?
Buying cream of tartar and baking soda (roast to get sodium carbonate) at the grocery store is neither expensive nor suspicious. It is also required
of the only procedure that I know of that is claimed to coat PbO2.
Maybe precipitated silver powder could be used to make your own silver paint. Mix the powder with a small amount of silicon oil, and apply between a
copper strap and the PbO2 electrode. I don’t know about soldering… PbO2 has a low decomposition point (290C), so you can’t get it too hot. Maybe
dusting the surface with silver and then pour a low melting wood’s alloy around that for a connection.
Yes, I think the problem is that PbO2 disintegrates as a cathode… at least if you tried using it as a cathode in a (per)chlorate cell. However, in
the procedure described in US Pat # 3,318,794 (that I think you are referring too) the lead dioxide anode is used as a cathode for the
electrodepositing of silver on the surface of the PbO2 anode. So it couldn’t disintegrate in this case. Perhaps the current density is low enough,
or maybe it has something to do with the fact that the anodes these are being applied to are plastic-bonded PbO2-powder “massive” anodes. It might
not even work on electrodeposited PbO2. It’s something that just needs to be tried IMHO.
-Alan
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jpsmith123
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Dann2 have you tried MnO2?
Supposedly MnO2 can be electrolytically deposited on a graphite substrate (or other substrate, although I understand it sticks to graphite very well)
from an aqueous MnSO4 solution, but it is the gamma form.
Then you could heat it to 300 degrees C or so and convert it to the beta form.
Maybe that's worth a try?
The thought just occured to me: Maybe for a quick test of the perchlorate making ability on MnO2 you could buy a chunk of the mineral pyrolusite
somewhere (I think I've seen some fairly big pieces for sale/auction on ebay). Pyrolusite is a naturally occuring form of beta Mno2.
[Edited on by jpsmith123]
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Rosco Bodine
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Regarding the silvering , never tried it , but ....
Possibly you could simply dip the portion of the electrode wished to be silver plated in a SnCl2 silvering catalyst ,
and then immerse that portion in a silver nitrate ,
ammonium hydroxide and hydrazine sulfate electroless
plating bath . You should get about a 60 micron (.0024 inch) plate in 4 hours .
There are other silver "mirroring" methods . IIRC there is a
document on this in the forum library . I am not sure ,
but it seems like I read that some of the electroless plating baths can also be driven with electricity when the substrate to be plated is conductive
.
Attached is an article concerning silver electroplating via a process which uses relatively common materials and involves
no cyanide . The process can be used to selectively plate out
silver from silver-copper alloys which have been dissolved in nitric acid , for example using coinage silver or sterling .
But there seems to be no reason why the same method would not work for a pure silver process also .
There's a bit more concerning plating from a straight silver nitrate solution on the following page
http://antoine.frostburg.edu/chem/senese/101/redox/faq/ag-fr...
[Edited on 29-5-2007 by Rosco Bodine]
Attachment: JCE Volume 36, Number 6, June 1959 Electrodeposition of silver and copper without the use of cyanide.pdf (2.4MB)
This file has been downloaded 1852 times
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Rosco Bodine
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Electroless Silverplating
That book on electroless plating must be on the forum FTP
because I didn't see it in the forum library .
The entire book is a 22 MiB file , so I made a smaller file
for just the chapter on silver .
I extracted the chapter on silver mirroring and am attaching it here .
What I said before about using electricity in combination with the electroless process may have been similar to the contact process , which simply
causes the initial coverage to form on a targeted area exposed to the plating bath . And once that
coverage completes the plating proceeds autocatalytically .
So it may be that what I was describing as the usefulness of electricity in combination with an electroless bath , was as a
substitute for the initial deposition catalyst , to kick start the
initial coverage . I really don't remember the context in which electricity may be used in combination with the electroless plating bath .....except
that it definitely can be used when the substrate is conductive .
Attachment: Electroless Silverplating Chapter from electroless_plating_-_fundamentals_and_applications.pdf (695kB)
This file has been downloaded 18775 times
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dann2
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| Quote: | Originally posted by jpsmith123
Supposedly MnO2 can be electrolytically deposited on a graphite substrate (or other substrate, although I understand it sticks to graphite very well)
from an aqueous MnSO4 solution, but it is the gamma form.
Then you could heat it to 300 degrees C or so and convert it to the beta form.
Maybe that's worth a try?
The thought just occured to me: Maybe for a quick test of the perchlorate making ability on MnO2 you could buy a chunk of the mineral pyrolusite
somewhere (I think I've seen some fairly big pieces for sale/auction on ebay). Pyrolusite is a naturally occuring form of beta Mno2.
[Edited on by jpsmith123] |
I have never got around to trying MnO2. Spending too much time thinking/talking about the stuff. I need to get my hands dirty a lot more (Lead Dioxide
work excluded:-|)
Would the Pyrosusite be conductive enough I wonder.
I am currently running a graphite (lump of edm) anode cell making Perchlorate to see how good it is and how much it wears.
Dann2
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jpsmith123
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I have a cell that I made from a pool chlorinator just sitting here, which I can't really experiment with until I move out of this small apartment,
hopefully sometime this summer.
As far as the pyrolusite, I've been trying to find some information about the conductivity, but so far no luck.
BTW, with regard to your graphite anode cell, did you start with chloride or chlorate?
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alancj
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| Quote: | Originally posted by jpsmith123
I have a cell that I made from a pool chlorinator just sitting here, which I can't really experiment with until I move out of this small apartment,
hopefully sometime this summer.
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If you are worried about it producing chlorine then just raise the pH of the solution with some NaOH, and it won't produce any chlorine. It will
basify by itself but when starting out with a neutral solution it will still generate enough Cl2 to be quite irritating before the pH gets up around
8-9. The current efficiency will suffer, however (but an anode just sitting around has a current efficiency of 0!  )
-Alan
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Rosco Bodine
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A patent mentions silver plating used under alpha? lead dioxide
A few times I have mentioned the idea of using metallic silver or silver oxide as an interface material , a conductive substrate or possibly as a
highly conductive dopant in mixture with other oxides . But I haven't been able to find any mention at all , much less any details of this idea having
been tested in anode construction ......until now anyway .
One brief sentence in US4064035 mentions the use of a silver mirror interface to improve the conductivity between a titanium substrate and lead
dioxide , but provides no details whatsoever . See page 3 , column 3 , lines 34 to 36 .
For context the paragraph describes anode substrate preparation , which involves degreasing prior to plating with lead dioxide , and goes on to say
that such pretreatment may be omitted when an alkaline plating bath for alpha lead dioxide is to be used for the first layer . However , the patent
states | Quote: | | Where the electrical conductivity is particularly required, the substrate is desired to undergo said pretreatment followed by a treatment for silver plating |
It is unclear to me whether this silvering necessarily applies to subsequent plating with either the alpha or beta lead dioxide specifically , or
both . But the technology more generally described by this patent is the basis for the method advanced later by other patents including those which
were the basis for alembics titanium substrate anodes having the stress relieved combination of alpha and beta lead dioxide layer construction .
Further , tin oxide does function as a silver deposition catalyst as described in the electroless silvering literature .
Not only is the tin oxide present on the titanium substrate
from the tin chloride dip and bake treatments , which produces a continuous coating for which silvering would have
a high affinity and adhesion ......but tin oxide would also be
deposited in trace amounts sufficient for catalysis of silver mirroring , when a substrate having any silica content is
simply dipped into a tin chloride solution .....no baking required as a pretreatment for mirroring with silver .
I believe this silvering scheme could be applied to many substrates such as ceramics which have some natural silica content which would be reactive
with a tin chloride dip treatment , as activation for a silvering interface , between a substrate and whatever form of lead dioxide is subsequently
electrodeposited onto that silvering . This might also apply to ordinary gouging rods , whose porous surface might even be an advantage . A carbon or
a porous ceramic possibly could be dipped into water glass , and then into an acid to form silicic acid in situ in and on the surface , then dipped
into tin chloride to deposit the tin oxide catalytic sites for silver deposition as an adherent and conductive interface layer for the lead dioxide to
be subsequently electrodeposited to complete the anode .
One of the ideas that has occurred to me is that a plain glass
stirring rod could be dipped into tin chloride and then mirror plated with metallic silver , and used as an inert physical substrate upon which to
electrodeposit a massive lead dioxide anode . Or a flat piece of unglazed one foot square
ceramic floor tile could be cut into 3 inch wide X 12 inch strips . Anyway , seeing the however brief reference in the
patent is encouraging because it indicates that silver plating specifically is at least one material which can be used as a conductive "primer" layer
onto which lead dioxide may be plated . This makes available as anode substrates any
material conductive or not by itself , which may be mirrored with silver to give it at least temporary conductivity and allowing a more durable layer
of lead dioxide to be deposited , which may subsequently be built up to any desired thickness as a massive or embedded substrate massive lead dioxide
anode .
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hashashan
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i believe that if it is possible(ive also heard about it) then you have to remain a perfect neutral PH because even dilute nitric acid will easily
dissolve the very thin layer of silver.
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Rosco Bodine
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The alkaline alpha lead dioxide plating bath based on
tartarate , acetate or plumbate would get around that .
I don't recall which type lead dioxide was plated out from a sulphamate bath .
Also , I wonder what might be the result of plating from a basic lead nitrate buffered normal lead nitrate bath ,
or even a basic lead nitrate / normal lead acetate bath .
Another idea I have for a stress relieved deposit , is using
a combination lead salts bath from which the alpha or the beta lead dioxides are precipitated preferentially at slightly different curent densities .
An unfiltered and unregulated but limited rectified DC from a transformer ,
might deposit the alpha lead dioxide during one part of the power waveform as the current changes and then
deposit beta lead dioxide in another part of the waveform , so that the alpha and beta lead dioxides are
continually electrodeposited as a mixture . There could be an optimum power frequency and ripple waveform profile which plates out an idealized
mixture of alpha and beta dioxides , which could be plated to any thickness desired , as it would be internally stress relieved at a microstructural
level .
Another idea I have is that a vibrator could probably be useful for mechanically dislodging tiny bubbles of oxygen
which might form pinholes on an anode being plated with lead dioxide . The first sort of simple vibrator which came to mind is the sort of vibrator
used in cheap aquarium pumps , where a magnet attached to the end of a leaf spring resonates in the rapidly reversing field at the
end of a small AC solenoid coil . There is probably a
resonant frequency peculiar to each anode structure
where the effect would be optimum , but I believe just
the generic vibration of an AC coil and magnet might do the trick well enough to be useful .
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dann2
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| Quote: | Originally posted by jpsmith123
I have a cell that I made from a pool chlorinator just sitting here, which I can't really experiment with until I move out of this small apartment,
hopefully sometime this summer.
As far as the pyrolusite, I've been trying to find some information about the conductivity, but so far no luck.
BTW, with regard to your graphite anode cell, did you start with chloride or chlorate? |
Hello,
Don't know if this is directly related to the Pyrolusite but you can purchase (natural) Magnetite in crystal shops, ebay etc but it is non conducting.
It is the few % of other stuff in it that makes all the difference for electrical conductance.
The Graphite Anode Perchlorate cell was started with 'pure'
Chlorate.
Pure in this case meaning Chlorate that was recrystalized twice from a Chlorate cell. I boiled down the Chlorate solution until crystals started to
form. The solution was let cool and then cooled to about -10C. The crystals were filtered in a cloth and quickly washed in cold water.
Crystals were dissolved in water again and solution boiled down etc. (Two crystilizations).
A solution of 500 grams of this Chlorate per liter of water was used as the start solution for the Perchlorate cell.
It tests positive for Chloride when a Silver Nitrate test is done.
I would have liked to have a zero Chloride content in the cell at the start but I got fed up with the crystalizing . I guess you could argue that the
solution I used in the Perchlorate cell is what an amateur will usually have.
I have kept samples of the starting solution which I intend to test with Silver Nitrate (how??) to get an idea of the Chloride % in the solution at
the start of the Perchlorate cell run.
The Graphite is wearing at a fairly linear rate of about 23 grams per 24 hours.
Current density is approx. 33mA per square cm.
Temp about 26C. Cell is sitting in a bucket of water.
pH uncontrolled (about 6 to 7)
Cell is two liters.
SS cathodes.
Computer power supply (5v) with Nicrome resistor (hot!)
to keep current fairly steady. Voltage accross cell about 3.6 volts.
The cell ran for about 1.5 days before Perchlorate started to show using Methylene blue test.
The cell has a 'run time' of about 50 hours. (I reckon)
Cell still running.
To get back to testing for Chloride. I do not have a large amount of Silver Nitrate. My scale only goes to the nearest 0.1 of a gram therefor it is
not practical to measure Chloride content using Silver Nitrate by weigning PPT of Silver Chloride.
I was going to do the following.
Make up a fairly dilute solution of Silver Nitrate.
Make up a range (say twenty litttle bottles ) of solutions of
NaCl solution going from 0.5% to 10% Chloride in 0.5% steps.
Put them in a row (drum roll starts HERE!!!!!!!!!!!!!)
I will then put a drop of the Silve Nitrate into each bottle which will give me a certain (hopefully noticably different)
opacity/white colour.
I will then compare the row of bottles to what a sample from my Perchlorate cell start looks like after a drop of the Silver Nitrate soluton has been
added.
Would this work do yis think.
The solutions of NaCl and Silver Nitrate need to be dilute (I can use a very dilute solution of Silver Nitrate) so that a fine ppt of Silver Chloride
is formed. If the solution are too concentrated you get lumps (literally) of Silver Chloride forming which are useless as a visual representation of
the Chloride content.
All rather crude but easy to do (If it will work).
I only want to find out the Chloride content to the nearest percent or so.
Suppose I could purchase a scale to .01 gram.........
Dann2
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not_important
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You need to keep the chloride concentration low enough that not all the silver is precipitated, otherwise all the silver drops out leaving some amount
of chloride in solution.
You'll want to do some constant dilution of the references and test solution, such as
1:100. Make the standards, and the test solution, using large enough amounts you can accurately weight them. Then take say 1 ml of the each solution
and add it to 200 ml of DW, and test 1 ml of that. Start with one of the reference solutions and see if the result is dilute enough that a drop or two
of AgNO3 solution ppts all the chloride - add one drop, let the ppt settle, add another drop of AgNO3, and so on. You can work the maths to see about
how much chloride can be in a ml for a known amount of the AgNO3 solution to full ppt all the chloride; do that for the highest concentration so that
all the more dilute solutions will also have all their chloride knocked down.
A method sometimes used is to use a long tube holding the (diluted) solution under test, and look into it from above at a lighted target. Using a
second tube, slowly add reference solution (again diluted) until the target is as hidden by the opacity to the same degree as by the solution under
test. And alternative is to side-light the tubes with a diffused linear light source, such as a fluorescent lamp or illuminated wall, and adjust the
amount of solution in one tube to give the same brightness of light scattered by the AgCl as the other tube - works with very dilute solutions.
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garage chemist
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What is "butyl titanate" supposed to be? The reaction product of TiCl4 and n-butanol?
And is Ruthenium one of the more expensive PGMs, or is it on the
affordable site (like, more or less expensive that Pt)?
I'll probably buy some titanium sheeting from ebay today, theres a bunch of it on there ATM.
And start making a DSA (MMO) anode, which doesnt sound difficult at all from the patent. You only need the ruthenium chloride and TiCl4. What do you
think, should I try it?
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Eclectic
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Ru MMO's won't make perchlorate AFAIK, just chlorate.
Ru is not so expensive as PGM's go, but finding someone who will sell a small amount is almost impossible.
Antimony/Tin oxide on titanium seems just as effective, easier to produce, and MUCH cheaper.
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