Sciencemadness Discussion Board

Thoughts On Anodes

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bbartlog - 20-6-2010 at 06:37

The theory he was referring to was this:
Quote:
A way around this is to use a second Pt-plated electrode as a cathode.


...as you would acknowledge if you weren't being deliberately obtuse.

hissingnoise - 20-6-2010 at 08:11

Well, he did say this. . .
Quote:

I have tried the platinum cathode and I can tell you that it is a very bad thing to do. I completely destroyed, (turned to powder), one of the 4 electrodes I bought, which leads me to believe that your idea of the platinum plating onto the cathode in normal operation is incorrect. It seems the plating goes from negative to positive, this is why, it seems, my platinum cathode completely dissolved in about 150 hours.

Everyone knows that Pt is resistant to everything except Aqua Regia and how many people are there who think that electroplating works by migration of metal from the cathode to the anode?



white rabbit - 20-6-2010 at 09:51



My point was simply, if the platinum is plating across, it is certainly not plating on the platinum cathode as you stated and Pt is certainly not electrochemical resistant as a cathode. So your statement that, "Pt is resistant to everything", is also incorrect.

hissingnoise - 21-6-2010 at 02:41

Quote:
also incorrect.

It's hot - I'm lazy!
Tim knows what I. . .

white rabbit - 21-6-2010 at 19:11



I will concede that platinum is indeed resistant but not impervious to electro/chemical attack. I really don't know what exactly happened to the platinum cathode but it really doesn't like to be negative in the electrolyte solution of the chlorate/ perchlorate cells.


This was my first usage of the platinum electrodes, both anode and cathode at ~70 hours at 6.5 volts / 25 amps. The anode appears to be completely unaffected and continued to look this way run after run with a stainless cathode.

Platinum Anode and Cathode small.JPG - 98kB


This was the beginning of the cathode corrosion, and quickly continued, until after removing the electrode from solution, and leaving it exposed to the air overnight, it crumbled to dust.:(

Platinum Cathode small.JPG - 58kB

hissingnoise - 22-6-2010 at 06:32

Quote:
I really don't know what exactly happened to the platinum cathode but it really doesn't like to be negative in the electrolyte solution of the chlorate/ perchlorate cells.

White rabbit, as you know, platinum is famous for its inertness to acidic and alkaline environments.
It certainly shouldn't noticeably corrode when used as cathode or anode in a chloride cell.
Perhaps the electrode was defective in some way. . .
Quote:

This was the beginning of the cathode corrosion, and quickly continued, until after removing the electrode from solution, and leaving it exposed to the air overnight, it crumbled to dust.

If the Pt plating was not continuous enough to fully protect the electrode, corrosion and hydrogen embrittlement of the substrate metal? could possibly account for what happened. . .
It's certainly curious and at the price of the electrode, the experience must have been pretty devastating.


white rabbit - 22-6-2010 at 15:26



You may have a good point there. That one electrode was never used as a anode. I have used three of the four electrodes so far and the two used as anodes still look like the day I first started using them. (The crusty residue washes of with water) The substrate material is niobium and is supposed to have an exceptional chemical resistance.

The price of the electrode was of no consequence, but I certainly didn't do the dance of joy.:o

Lambda-Eyde - 22-6-2010 at 15:45

Quote: Originally posted by hissingnoise  

Everyone knows that Pt is resistant to everything except Aqua Regia and how many people are there who think that electroplating works by migration of metal from the cathode to the anode?
Quote: Originally posted by hissingnoise  

It certainly shouldn't noticeably corrode when used as cathode or anode in a chloride cell.
Perhaps the electrode was defective in some way. . .


Platinum metal may dissolve if free chlorine is liberated at the anode.

Ref: Kvantitativ Analyse ("Quantitative Analysis"), Katrine Seip Førland, Tapir Academic Press (1984)

BDD Makes Perchlorate

jpsmith123 - 19-7-2010 at 12:39

I recently came across the following interesting abstract. I've been loosely following the development of BDD anodes for a while now, looking for experimental confirmation that they will in fact make perchlorate. The results stated here seem to verify it, and it sounds promising, IMO.

The other important question, still unanswered AFAIK, is: How well would a BDD anode hold up in a perchlorate cell?

In any case, it seems to me that it might now be worth buying that small BDD slab available from e6 corp. to do some testing. The main issue there is: How do you make an electrical connection to it?

Electrochimica Acta
Volume 54, Issue 7, 28 February 2009, Pages 2102-2107
ELECTROCHEMISTRY FOR A HEALTHY PLANETENVIRONMENTAL ANALYTICAL AND ENGINEERING ASPECTS Selection of papers from the 6th ISE

Spring Meeting 16-19 March 2008, Foz do Iguacu, Brazil

doi:10.1016/j.electacta.2008.09.040
Copyright © 2008 Elsevier Ltd All rights reserved

The occurrence of perchlorate during drinking water electrolysis using BDD anodes

M.E. Henry Bergmann, Johanna Rollina and Tatiana Iourtchouka
Anhalt University, FB 6/7, Bernburger Str. 55, 06366 Koethen, Germany
Received 30 April 2008; revised 15 September 2008; accepted 17 September 2008. Available online 27 September 2008.

Abstract
Electrochemical studies were carried out to estimate the risks of perchlorate formation in drinking water disinfected by
direct electrolysis. Boron Doped Diamond (BDD) anodes were used in laboratory and commercially available cells at 20 °C. The current density was changed between 50 and 500 A m−2. For comparison, other anode materials such as platinum and mixed oxide were also tested. It was found that BDD anodes have a thousandfold higher perchlorate formation potential compared with the other electrode materials that were tested. In long-term discontinuous experiments all the chloride finally reacted to form
perchlorate. The same result was obtained when probable oxychlorine intermediates (OCl, ClO2, ClO3) were electrolysed in synthetic waters in the ppm range of concentrations. The tendency to form perchlorate was confirmed when the flow rate of drinking water was varied between 100 and 300 L h−1 and the temperature increased to 30 °C. In a continuous flow mode of operation a higher chloride concentration in the water resulted in a lower perchlorate formation. This can be explained by
reaction competition of species near and on the anode surface for experiments both with synthetic and local drinking waters. It is concluded that the use of electrodes producing highly reactive species must be more carefully controlled in hygienically and environmentally oriented applications.

dann2 - 19-7-2010 at 12:46

Hello JP,

Good to see you posting again.
I have not been doing much lately in the Chlorate/Perchlorate line.

The BDD sounds like a great Anode.

Dann2

jpsmith123 - 23-7-2010 at 20:33

Hi Dann2,

I've been tinkering with electrical stuff and putzing around with a mini-lathe, but seeing the above abstract has re-ignited my interest in BDD anodes.

I was following this thread for a while, but now it seems most of the participants have moved on to other things.

Anyway, I'm going to start seriously looking again to see if I can buy some niobium/BDD anode material somewhere at a reasonable price. I'll post here if I have any luck.

watson.fawkes - 24-7-2010 at 05:57

Quote: Originally posted by jpsmith123  
The main issue there is: How do you make an electrical connection to it?
Think about using vacuum deposition. Given that the technology was invented by Thomas Edison (yes, really, it surprised me), it's certainly achievable in a home lab, particularly now that refrigeration service pumps are so common.

jpsmith123 - 24-7-2010 at 06:39

Being that the diamond is doped with boron, it's an electrical conductor (although not a very good one according to the specs), so it might be possible to metallize it by simple electroplating, for that matter, and then something could be soldered or brazed to it.

I think the main problem is that the metal-to-diamond joint will be exposed to the environment of the chlorate/perchlorate cell, so most common materials would probably not last very long.

I remember seeing a patent from 50 or 60 years ago wherein diamond powder was metallized and attached to the metal core of a grinding wheel using a paste of TiH2. The assembly was then fired to 400 or 500 degrees C in a furnace.

That's probably something like what you'd have to do to make a reliable connection to it, i.e., a direct diamond to valve metal bond.

In any case, another disadvantage of trying to use bulk BDD slab material available from e6, is that the conductivity of the material is rather low, so, depending to a certain extent on how you connect to it and use it, the current you could put through it would probably be limited to a few amps.

Quote: Originally posted by watson.fawkes  
Quote: Originally posted by jpsmith123  
The main issue there is: How do you make an electrical connection to it?
Think about using vacuum deposition. Given that the technology was invented by Thomas Edison (yes, really, it surprised me), it's certainly achievable in a home lab, particularly now that refrigeration service pumps are so common.


[Edited on 24-7-2010 by jpsmith123]

dann2 - 28-7-2010 at 12:51

Hello Folks,

Have a look at:

http://www.advoxi.com/products

These things may be available in the dumpsters soon. (like the MMO)

Still getting around to the SnO2/Bismuth doped Anode to see if it's any good. Perhaps next month.

Dann2

[Edited on 28-7-2010 by dann2]

diagram04.jpg - 23kB

jpsmith123 - 28-7-2010 at 20:27

Thanks for that link Dann2.

I'm going to email them and find out what's available and at what price.

jpsmith123 - 3-8-2010 at 14:20

Unfortunately, I found out that they won't sell just BDD anodes, but only the whole electrolytic cell. Even more unfortunate is the price...they want over $5000 US dollars for a small cell for swimming pools (if I've converted the currency correctly).

So it looks like that company is out. Rats. We need to keep looking I guess.

dann2 - 3-8-2010 at 15:49

Thats bad news!

If you Google

homemade boron doped diamond

some interesting looking links appear. I did not read them yet though. They seem to suggest that it may be possible to do it in an Amateur setting.


Also De Beers BDD Electrodes are distributed by Windsor Scientific, Slough, UK

http://www.windsorscientific.co.uk/index.php?main_id=92&...

240 pounds sterling for a disk 3mm in diameter. (ouch). The damm thing is hardly much bigger that a good sized full stop!

If it made an everlasting Perchlorate Anode though.........

Perhaps someone who is a bit flush with cash could stand into the breech.

Cheers,
Dann2 (holding on tightly to his hard earned cash :D )



[Edited on 4-8-2010 by dann2]

white rabbit - 3-8-2010 at 17:40

Buy the platinum anode and you're done. It saves 100's of hours of your precious time looking for alternatives.

jpsmith123 - 4-8-2010 at 09:40

No doubt platinum is great anode material, but it seems BDD has the potential to be much better: more efficient at making perchlorate, more robust and longer lasting, and hopefully, someday, significantly cheaper.

BDD may even be able to do things that, AFAIK, other anode materials can't, e.g., directly convert HCl onto HClO4.

I thought by now somebody would be doing something with "poly(hydridocarbyne)", i.e., applying diamond films to substrates by thermolysis of a precursor solution, similar to how MMO anodes are made.

I thought the patent holders (the processes to make the poly(hydridocarbyne) are patented) would have an interest in developing applications like this for their invention. Apparently not.

jpsmith123 - 20-8-2010 at 22:44

Well it seems it'll be awhile before BDD anodes compete with Pt or PbO2, for our purposes at least.

The best price I've got so far is 960 Euro for a BDD over Nb plate anode of dimensions about 7.5"x3.25"x0.1" with a 5 micron BDD coating on both sides.

The recommended current density for this anode is 100 ma/cm^2.

The manufacturer says it is suitable for perchlorate electrosynthesis, which again confirms what we've already concluded.

As I understand it, BDD does slowly wear away, supposedly as OH attacks and damages it where there are defects in the crystal structure, or something like that. But it will nevertheless last a long time, maybe 10,000 hours or more of continuous use under harsh conditions.

I had hoped that, by now, conductive (boron doped) diamond powder would be commercially available...alas it isn't, as far as I know. Which is unfortunate as it seems to me that an electrophoretically coated platinum or MMO anode would be the easiest way to make a BDD anode at home.

Another method might be thermolysis of "poly(hydridocarbyne), with the addition of some boron compound as a dopant.
And I'm really surprised that nothing seems to be happening with this stuff.

Lastly, it may be possible to rig up a homemade cvd apparatus and make BDD at home, but I certainly don't have the resources to even try right now.

Luckily, it's been shown possible to make high quality BDD using alcohol vapor instead of methane and hydrogen gasses, and it's been shown that boric acid can be added to the alcohol as a boron dopant.

Also, luckily, the vacuum requirements are lax, so a simple water aspirator might suffice instead of a rotary vane vacuum pump.

The two remaining technical hardships would be (1) keeping the substrate temperature between 700 and 900 degrees C (or something like that); and (2) creating the plasma with which to dissociate the vapor into the active species.

It's possible that a dielectric barrier discharge can be used instead of a hot filament or a microwave (or RF) plasma, but I couldn't find any specific examples in the literature where a DBD was used (although I didn't look very thoroughly). If DBD will suffice for this purpose, I can see the apparatus being greatly simplified...with the major PITA being finding the optimum combination of pressure, discharge power, electrode spacing, etc.

dann2 - 24-8-2010 at 04:22

Quote: Originally posted by jpsmith123  

The best price I've got so far is 960 Euro for a BDD over Nb plate anode of dimensions about 7.5"x3.25"x0.1" with a 5 micron BDD coating on both sides.

The recommended current density for this anode is 100 ma/cm^2.


Thats not too far off from the price of Pt.

Dann2

jpsmith123 - 25-8-2010 at 11:08

I think e6 has convinced me that, with regard to presently available commercial technology, bulk BDD, rather than BDD coated substrates, is the way to go for diamond anodes. (Although I think it's possible someday that thick, electrophoretically applied coatings over the right substrate might be an exception).

Apparently e6 experimented with both BDD coatings and bulk material, and decided the latter was best. It seems that the coatings can develop pinholes which ultimately result in delamination of the coating. This is apparently why manufacturers of coated anodes recommend limiting the current density to 100 mA/cm^2, whereas the bulk BDD anodes can run from 0.5 to 1.0 Amp/cm^2.

Their literature predicts a life expectancy of >45,000 hours, when running at 0.5 A/cm^2.

A piece of BDD that's 20 x 20 x 0.6 mm would cost around $200 USD.

densest - 25-8-2010 at 12:51

Anyone in the UK have a moment to talk to these people?

Advanced Oxidation Limited
Unit 1
Homelands Business Centre
Burrington
Umberleigh
North Devon
EX37 9JG
United Kingdom

Telephone:
Alan +44 (0)7811 541339
Paul +44 (0)7702 707228

They say they sell wastewater treatment units containing BDD anodes including ones for spa/hot tub/pools.

metalresearcher - 8-9-2010 at 12:03

Where can I get platinum metal sheet or wire ?
Jewelry supply shops like cooksongold.com sell only jewelry grade Pt which is Pt alloyed with 5% Cu which is unsuitable for anodes as the copper is dissolved (AFAIK).
On Ebay I cannot find pure platinum for the 'normal' day price of $1600/oz or only slightly above which is 1600/0.031= EUR 51200/kg only for MUCH higher.

hissingnoise - 8-9-2010 at 12:11

The biggest suppliers of PGMs are Johnson Matthey and Degussa - check them or their subsidiaries out first!

dann2 - 22-9-2010 at 12:42

<center> THERE IS NOT ENOUGH WORK GOING ON AROUND HERE :P</center>


To hurry things up I lined up six cells in series to test 4 ATO Anodes that were made using SnCl2:2H2O. Antimony/Tin Solder should do as a substitute IMO for the

SnCl2 + Antimony Chloride that I used. The SnCl2 was purchased on Ebay as Tin Mordant. Antimony Chloride was made from the metal + acid + H2O2. The other two cells are Mn Dioxide Anodes that I am running for a few hours to leach out some of the 'less adhering' Mn stuff. I intend to
run them in two cells later, one being pH controlled and one not. Hopefully the pH controlled cell Anode will show a much longer liftetime?
The cells are various colours, as I connected the set up backways by mistake for about a half minute and the Copper Cathodes cast off various coloured stuff during this time.
The Mn cell have since turned a purple colour. The Anodes are 7 coats of Mn Nitrate of approx. 22 grams of wet crystals dissolved in 100ml distilled methylated spirits with colour as shown in picture. They were baked at 490C for ten minutes (seven bakes total) roughly as per US Pat No. 4072586. No other coatings.
One of the ATO coatings has since failed. It was made with water in the Ethanol which was blamed for the failure.

Dann2




mn.jpg - 18kB

dann2 - 22-9-2010 at 12:48

forgot six cells in series

six.jpg - 39kB

jpsmith123 - 27-9-2010 at 11:18

Hi Dann2,

Good to see you're still experimenting.

I recently found a Chinese manufacturer of conductive (boron doped) diamond powder...or at least I think they make it.

According to the following:

http://www.nanozl.com/english/product.htm

Their "grey nanodiamond powder" seems to be available with boron doping.

I'm going to inquire about it. If it's not too expensive it might be worth buying some for an experiment.

dann2 - 3-10-2010 at 16:50

Hello JP,

I often wondered of the Diamond powder could be put into a Lead Dioxide plating tank where it would physically incorporate itself into the LD and perhaps improve it performance. Not really a Diamond Anode but if cheap enough would be worth attempting.

I attach a patent (this patent would have been posted before somewhere or other) that states that Sn Oxide + Bi Oxide is 'useful' for Perchlorate production.(example 3 at the bottom)
I attempted the procedure without success. The Titanium was passivated before it even went into a cell.

I used Bi Nitrate (made form Bi metal and Nitric acid) + Tin Tetrachloride as per the instructions.

Is there possibly a mistake in example III ?
It states that Bi Nitrate is used (along with Tin Tetrachloride, SnCl4).
Should that be Bi Chloride (BiCl3), which would be the more usual way for making doped Tin Oxides (using Chlorides only).

I also tried adding HCl (35%) to the precursor as most of the precursors that use Chlorides only, have acid added. I had no success with that either.

I am currently trying to make BiCl3 using Tin/Bi alloy by dissolving out the Tin using HCl only and being left with a fine powder of Bi that will hopefully react to form the Chloride when I add HCl + H202.???

Perhaps you have to generate HCl gas to make Bi Chloride.

Dann2

Attachment: US 4272354 Example of SnO2 +Bi2O3 for (Per)Chlorate.mht (49kB)
This file has been downloaded 969 times

[Edited on 4-10-2010 by dann2]

jpsmith123 - 5-10-2010 at 21:12

Hi Dann2,

Well the Chinese co. got back to me and unfortunately they don't make conductive diamond powder. Supposedly they referenced it on their site for purposes of comparison or something. Rats! Foiled again!

Anyway, it sure would be nice if SnO2/Bi2O3 or something similarly within reach would make ClO4.

As far as your efforts to duplicate example #3 in that patent, all I can say is, in my experience with patents, I've found that some details are often left out, or something is left somewhat vague. Possibly deliberately.

I wouldn't be a bit surprised if they failed to mention an additive used in a small quantity to protect the Ti surface during thermolysis.

As a work-around, using the Bi(NO3)3 you have now, just for purposes of a quick test of the coating for perchlorate production, what about using a piece of MMO coated Ti as a substrate?

Do you have a small piece of MMO anode lying around?

And if it works and works well, then it may be worthwhile to try some other precursors, etc.

Rosco Bodine - 6-10-2010 at 11:59

@dann2

You were asking over in General Chemistry about how to make BiCl3, which I can safely presume is destined to be used as a dopant for baked SnO2. Really it is likely that alcoholate derivatives or sols are likely to perform better.

You should be able to precipitate Bismuth Hydroxide Bi(OH)3 by neutralization of Bismuth Nitrate Bi(NO3)3 - 5 H2O with Ammonium Hydroxide NH4OH. Bismuth Hydroxide may then be filtered and rinsed, then added to concentrated HCl to form BiCl3. However, as a precursor for a Bi2O3 sol and dopant for SnO2 the BiCl3 is probably not the best candidate, as the BiCl3 will tend to hydrolyze to an insoluble precipitated oxychloride BiOCl upon dilution with water, because the BiCl3 is only stable and soluble in strongly acidic solution. A better strategy for producing a stable sol would be to react the Bi(OH)3 with additional ammonia to form Ammonium Bismuthate derivative which would also be compatible and miscible with a similarly made Ammonium Stannate. Ammonium Antimonate could similarly be included in small amount as a grain refiner for the DTO baked coating,
although an ammonia soluble derivative of Cobalt Acetate may be superior in that regard.



Attachment: US6777477 Bi2O3 or Sb2O3 doped SnO2 via ammnonia soluble derivative.pdf (67kB)
This file has been downloaded 702 times

dann2 - 6-10-2010 at 14:31



Thanks for replys.

I am currently trying to make BiCl3 using Aqua Regia. It states in Kirk-Othmer that it works. Simply dissolve Bismuth and evaporate to get BiCl3:2H20. You can go on to get the Anhydrous by distilling but the hydrate will be OK for me (I think, as it is OK to have water in ATO precursor made from SnCl4:5H20 so it should be OK for BTO).
I would prefer (at this stage) to try the more common or 'garden' method of obtaining SnO2/Doped-with-something on Ti. It works easily enough with ATO (using SnCl4:5H20 + Antimony Chloride + Alcohol Solvent(some water too if you like) + HCl acid). Surly the Bismuth TriChloride can be substituted for the Antimony Chloride?
The patent used Bi Nitrate with SnCl4:5H20. Perhaps Bi Trichloride will not work, will just have to try.

Another method to make Bi Trichloride (from Kirk-Othmer) is to take Bismuth Nitrate (acid solution) and add KCl. Supposidly you can precipitate the BiCl3:XH20. The Aqua regia sounds more simply and straight forward.

I was surprised to find Bismuth metal was so stubborn (like myself) :D
It dissolved easily in Nitric acid (and Aqua Regia)



I could try something like what JP has suggested with MMO but with ATO (Antimony Tin Oxide) on Ti instead. (I actually DO have MMO lying around but I will go with the ATO on Ti)
Put ATO onto Ti, that's an easy job and works. Then start coming with some sort of BTO (Bismuth Tin Oxide) on top. Since the Ti has now been coated and will not passivate when the coats of BTO (using Tin Chloride and Bi Nitrate or some other precursor that is not required to keep the Ti passivated during the subsequent bakes) are put on top.
What ever physics/Chemistry happens in the few minutes of the baking of the first coat on the etched Ti is the difference between the Ti passivating and not passivating. That first coat is very fickle AFAICS when going with Tin Oxide.

Rambling on again.............

Dann2

Rosco Bodine - 6-10-2010 at 17:54

You are getting passivation, so you need something to anti-passivate the interface layer between substrate and barrier coatings.

IIRC the only chloride based precursor which had good success at anti-passivating Ti was ruthenium....but because ruthenium is so expensive a substitute dopant was sought and the cobalt spinel was found to be a promising substitute for the interface. There was some test data that by strong inference showed an even more durable interface could be gotten from a mixture of cobalt and nickel in the range of 70:30 to 50:50 based on the mixed nitrates precursor. I say inference because the tests were actually done on multiple layered coatings, rather than a single interface coat.

http://www.sciencemadness.org/talk/viewthread.php?tid=9572&a...

See this file:
Attachment: Spinel oxide coated titanium anodes-preparation and characterization.pdf (133kB)
http://www.sciencemadness.org/talk/files.php?pid=111836&...

But the effect there would tend to be additive, so it is a reasonably safe bet that a single interface coat of the mixed spinels is tougher also. The presence of nickel had also been reported as a grain refiner on electrodeposited PbO2. The antimony works a similar way with regards to SnO2 and in very small percentages there (1 or 2% of the total DTO ) it reduces the crystalline grain size and results in a smoother and denser, harder, tougher baked coating. However, so does cobalt spinel do the same even better, so it would seem like layering over a single dip and bake "interface coat" of mixed Co-Ni anti-passivated Ti substrate with a thickened undoped ammonium stannate sol would be a good strategy, as it would pick up doping from diffusion of whatever excess of free spinel was residue atop the anti-passivation layer formed on the first bake, and seal that interface in the overlayered glassy diffusion doped SnO2. Then layer after layer of Bi doped SnO2 could be applied using the PVA thickened sol of ammonium stannate and ammonium bismuthate, which builds a coating thickness at about five times the rate of anything else and should produce a pore free oxygen barrier coating. As a working coating, something of a different composition may be better, or the coating may just need to run for awhile to become active by eroding to an extent that some porosity and surface area increase occurs. All of this is theoretical but it is logical.
I actually have an idea that something of a mix of dopants may be advantageous in a DTO working coating where different dopants have different catalytic effects, and the SnO2 dopants mix could include a bit of this and that, including Sb, Co, Mn, Bi, F, and Pb as seasonings for the stew. Think catalytic multi-vitamin :D

You might try the oxalic acid etch too. I have gotten nearly all the materials and tooling to proceed with my own anode experiments...but I presently lack the bench space to put everything in operation.

Edit: I may be on a roll here so why stop brainstorming, (or stepping in it as the case may later prove to be ) :P
Anyway, for some time I have thought about the use of oxalates as a potential dopant precursor which could have advantage for killing two birds with one stone in the etching,
for being compatable with any Ti oxalate residue and / or to allow a partial "conversion coating" interface. It seems clear that the Nickel Cobaltite Spinel makes a tougher and more conductive anti-passivation interface than does the unsubstituted cobalt spinel and coincidentally the nickelous oxalate and cobaltic oxalate precursors are "valency steered"
by the selective reducing property of oxalic acid for nickel to a favorable chemical alignment for the formation of nickel cobaltite. Attached is an old JACS article which describes the reactions whereby this occurs on treating the mixed hydroxides of nickel and cobalt with oxalic acid. So this peculiar effect involving the oxalates may be worth an experiment to see if a mixed nickelous and cobaltic oxalate precursor in excess oxalic acid would perhaps make an ideal
precursor mix for a baked "one coat" Nickel Cobaltite Spinel anti-passivation layer on a Ti substrate. Also attached is a second article of possible interest regarding Nickel Cobaltite Spinel. Definitely there is food for thought and possibility involving the mixed oxalate precursor scheme and hopefully the solubilities of the oxalates are sufficient that it is workable.

Attachment: Nickel Cobaltite JACS article.pdf (335kB)
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Attachment: Nickel Cobalt Spinel.pdf (180kB)
This file has been downloaded 978 times

[Edited on 7-10-2010 by Rosco Bodine]

Rosco Bodine - 7-10-2010 at 18:53

Update concerning the solubility of cobalt and nickel oxalates. The solubilities in neutral solution or oxalic acid solution are very low, however both are freely solubile in a solution of ammonium oxalate made basic with ammonium hydroxide.

Therefore a basic, rather than an acidic precursor coating solution would be required using the oxalate precursors. The pyrolysis of the oxalates creates a reducing effect from evolved CO which should inhibit the growth of TiO2 and promote a spinel doped Ti suboxide interface layer.

Acetate or formate based precursors may work similarly.

Bi doping of SnO2 precursor sol via Pytlewski Polymer

Rosco Bodine - 8-10-2010 at 14:22

I just found something for which I have been searching,
which is a means of chemical isolation of ultra pure Bismuth metal as a reduced metal powder precipitated from solution .... a similar kind of chemical reduction as is used for producing reduced metallic copper by use of vitamin C.

See attached page from Thorpe, upper right part of page.
See attached page from American Druggist detailing the Lowe procedure for reduced metallic bismuth powder.
US3458308 describes a pyrophoric precipitated Bismuth,
and evidently Vitamin C can also be used for the reduction.
Keeping the precipitated Bismuth wet and proceeding immediately with the use of it in subsequent reaction would be a wise precaution respecting the reactivity of such material.

Evidently a reducing sugar will precipitate metallic Bismuth in ultra pure form from an alkaline solution of an alkaline bismuthate, and this should work for ammonium bismuthate using dextrose, or fructose, corn syrup, ect. to provide a finely divided pure metal dust of Bismuth as a precipitate.

This reduced Bismuth metal can then be heated and stirred with a solution of Stannic Chloride to produce a mixed sol,
wherein the Bismuth dopant for the SnO2 is chemically bound and resident in an inorganic polymer form of hydrated SnO2 which should pyrolyze to a Bi doped SnO2 coating.

This "Pytlewski Polymer" is a Bi doped SnO2 sol which can also function as a wetting agent / substitute surfactant between coatings of other materials, simply by dipping the anode into this Pytlewski Polymer and air drying, before application of other precursors. Theoretically, this material should act as a bonding agent for the other coating layers.

Attachment: pure metallic (reduced) Bismuth page from Thorpe.pdf (262kB)
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Attachment: US3890429 STANNIC_OXIDE_POLYMER_Film Wetting Agent.pdf (399kB)
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Attachment: reduced metallic bismuth.pdf (435kB)
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Attachment: US3458308_Reduced Bismuth metal powder pyrophoric.pdf (73kB)
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[Edited on 9-10-2010 by Rosco Bodine]

What about a different approach?

jpsmith123 - 9-10-2010 at 11:22

If SnO2/Bi2O3 will make perchlorate, then what about the following method (substituting oxides of course). This is from one of Beer's patents and I don't recall which one:

"Niobium was degreased and subsequently provided with an oxide coating of a thickness of at least 1 micron. This can be effected either electrolytically or thermally.

Subsequently a paste was prepared of:

10 cc. ethanol
1 g. ruthenium oxide
4 g. titanium oxide

This mixture was intimately admixed, heated, sintered, comminuted, and again mixed with 10 cc. ethanol. The
resulting paste was applied to the oxidized niobium in a thin layer, and subsequently heated at a temperature of
450-700" C. This treatment was repeated until at least 10 g. of the desired mixture per m^2 was present on the
surface. A niobium plate thus treated is excellently suitable for the electrolysis of electrolytes."

Maybe the powdered oxides could be mixed and then heated in a microwave kiln, then ball milled, then either made into a paste and applied to a substrate and baked as per above, or maybe something similar to what's described in this post could be done.

Edit:

I just reread example 3 of patent# 4272354, and if I understand correctly, they're saying that just mechanically mixing the two powders together (SnO2 and Bi2O3) and apparently just sticking the mixture into the hopper of a plasma coating machine, can produce a good anode.

If that's the case, that might be the way to go - just find a plasma coating shop that does small jobs.

[Edited on 9-10-2010 by jpsmith123]

Rosco Bodine - 9-10-2010 at 12:30

Some worthy suggestions having good theoretical basis derived from an extensive review of the literature and having a chance of working well have been made. Will it work ? ....I do not know. I mean to find out ( regarding the Pytlewski polymer, ammonium stannate PVA thickened hydrosol, nickelous cobaltite interface, ect. ) There are already reported schemes for mixing fillers with working anode coatings to reenforce the strength, fibrous alumina was something already discussed. Silica and zirconia and TiO2 can be used too.

A lot of this discussion is becoming circular. Composition and pH of the precursors for a baked coating and "wetability" of the substrate have bearing on the adhesion of the baked coatings. The methods which I have been proposing have a good chance of resolving the identified problems.

http://www.sciencemadness.org/talk/viewthread.php?tid=8253&a...

Hydrosols are stable pH and can be adjusted in pH

http://www.sciencemadness.org/talk/viewthread.php?tid=5050&a...


[Edited on 9-10-2010 by Rosco Bodine]

Interesting Video on Youtube - making a coated Ti anode.

jpsmith123 - 12-10-2010 at 08:36

http://www.youtube.com/user/NurdRage#p/u/21/BjKYiu8eKa8

Xenoid - 12-10-2010 at 10:36

Yeah! I saw that a couple of weeks ago.

I wonder where he got the idea from? No acknowledgements though ;)

At least he admits it doesn't work very well - :D

jpsmith123 - 12-10-2010 at 12:37

That guy's also got some other pretty good science related stuff on youtube.

BTW Xenoid, I'm wondering, did you happen to try anything with SnO2/Bi2O3 in any of your experiments?

Xenoid - 12-10-2010 at 13:35

Quote: Originally posted by jpsmith123  
That guy's also got some other pretty good science related stuff on youtube.

BTW Xenoid, I'm wondering, did you happen to try anything with SnO2/Bi2O3 in any of your experiments?


Yes, he's quite a hit with the Teeny generation, have a look at some of the comments!

Nurd Rage! Nurd Rage! You're my hero, Nurd Rage! :D

I wonder if the guy is a ScienceMadness member, the betaMnO2 over Co3O4 was only described in ScienceMadness, basically Rosco's idea, I don't think it was mentioned in any of the patents.

I had a bit of a medical emergency last year and haven't been doing much. Though this year I have been playing around with perchlorate anodes, based on thermally coating commercial MMO anodes with various oxides. Seems quite promising, but I need a way to, at least semi-quantitatively, analyse perchlorate, so I can make some comparisons. Not as easy as it may seem!

Have'nt really done much with SnO2, but I may give Dann2's SnCl2 method a try!

jpsmith123 - 12-10-2010 at 15:43

Well Xenoid I hope your medical issues have been successfully resolved so you can get back to some serious "sciencemadness"!

I've been putzing around with a mini-lathe and a few things electrical - but still keeping an eye peeled for any advancements in BDD technology or availability of cheap BDD material. So far to no avail, unfortunately.

In fact I now believe that, absent a major technological advancement, commercial BDD anodes will not be cost competetive with Pt based anodes (for perchlorate synthesis at least), anytime soon.

Anyway, I have a "gut feeling" that the SnO2/Bi2O3 combination might work. If Dann2 reports anything positive, I'm going to clear off some of the little bench space I have and order some chemicals.

dann2 - 13-10-2010 at 13:37



Hello Folks,

Hope you are doing fine Xenoid. These things come and go.
SCIENCEMADNESS is as good as any medication or doctor!


There is a blow by blow account of the SnCl2 method here:
http://www.oxidizing.110mb.com/chlorate/atocl2.html

There is a guy over on the General section fusing SnO2 (can be got in ceramics store) and NaOH. It may be another viable way to get Tin compounds OTC.

The Antimony/Tin Oxide stuff is not great for Chlorate or Perchlorate making but it is tough stuff and seems to last a long time.

I am waiting on some HCl to start making Bismuth Trichloride (via Aqua Regia). The Nitrate does not work as far as I can see.

I am currently running some Manganese Anodes in Na Chlorate cell. The Anode with Manganese Nitrate decomposed onto bare (etched) Titanium is working OK. I put on five (only, I was lazy) coats and it has now lasted 18 days at approx. 50mA per square CM. The Voltage accross cell is still steady (no sign of passivation). I will soon have to change electrolyte as Chloride is getting below 100g per liter.

There is a guy over in General dissolving Palladium. It may be worth trying in a SnO2 Anode (instead of Antimony) as Palladiium is relatively! cheap. It's about 40 quid for a gram coin. JP suggested this way back as a 'DSA'. Might be good for Perchlorate.
Pt Oxide makes Perchlorate AFAIK. It's expensive for messing about with. If you had a KNOWN working formula for an Anode it would be much more affordable.

Dann2

Rosco Bodine - 13-10-2010 at 20:00

This may be interesting. Ever seen a cotton candy machine ? Here is a patent US5330833 for a spun SnO2 fiber material which is ATO or DTO, depending upon the dopant material. It is derived from SnCl2 and an alcohol which are refluxed to produce the sol-gel precursor, having a sticky viscosity so great it can be drawn and spun into fibers just like molten sugar can be spun into cotton candy. Evidently it is exposure to low atmospheric moisture which very quickly causes the alcohol solvated syrupy viscous sol-gel to further polymerize, harden and set to a rigid fiber.

It is very likely that a bismuth doped formulation could also be made, or any of many different other dopants could be included also. Several forms of soluble bismuth or other dopants could be made part of a precursors mixture of this sort.

Attached also is US1935178 which describes in very general ways the conditions under which hydrous oxide gels and sols can be deliberately formed from an assortment of metal salts.

Attachment: US5330833_Tin_oxide_fiber_spun_from_SnCl2_alcoholate_derived_viscous_ sol-gel.pdf (206kB)
This file has been downloaded 740 times

Attachment: US1935178 Method Of Making Gels.pdf (501kB)
This file has been downloaded 822 times

[Edited on 14-10-2010 by Rosco Bodine]

jpsmith123 - 14-10-2010 at 22:19

Well I found some SnO2 that I forgot I had. I think it came from a ceramics supply place.

Does anyone know if SnO2 will dissolve in oxalic acid?

(BTW does anyone know generally how pure are the oxides that these ceramics supply houses sell?)

12AX7 - 15-10-2010 at 07:28

Well, pottery MnO2 might be crude ore (pyrolusite), with lots of iron. That's probably the lowest purity chemical available. Many have to be pure, otherwise they'd screw things up (for instance, iron impurity causing spots and streaks).

Something like SnO2 might be ore as well, but IIRC it's flotation seperated, which might result in higher purity than crude MnO2 for instance. If that's not good enough for its use, then it's probably refined somehow chemically. Easy way to guess: if it looks precipitated or calcined, it's probably processed; if it looks ground up or natural, it's probably raw.

Tim

patsroom - 26-10-2010 at 21:52

I see some are still trying to make Pb02 anodes. The good news is you can buy them. Factory make for pre chlorate production. The bad news they cost about 55 USD plus shipping and handel charges costing more.
I once asked if any one was interested a year ago, no real takers then.Oh wel....................Patl

dann2 - 27-10-2010 at 06:06

Hello Patsroom,

Can you refresh us on the source and price and quanity that must be ordered to get some of them. Thickness is the LD coat and what is the total surface area of the Anode. Cheers.

Been doing some Manganese Dioxide stuff. Made an Anode of Manganese Dioxide deposited onto bare Ti and it worked OK. 5 coats lasted approx. 30 days at 50mA per square cm in a Chlorate cell. (XENOID got 48 days from 10 coats + some Co coats, but CD was up at 100mA for a while). There was no pink colour at any time, just brown crud that sank to the bottom when cell was stopped.
Next Anode up was a Mn Oxide (5 coats) with two coats of Cobalt Oxide put on first. The solution turned pink as soon as the cell was started. It looks as if the Co Oxide caused the Mn to come of in its 'pink' valency state. (not too well up in valency states).
There is no need for the Co undercoat (as suspected). The time would be better spend putting on two extra coats of Mn Oxide and no need to obtain extra materials (ie. Co) IMO.

Running the (in)famous divided Perchlorate cell with a Graphite Anode. Wil report. Don't expect any breakthroughs...............................

Can't get BTO to form using either the Bi Chloride or Bi Nitrate (with SnCl4:5H20)

Dann2
More Mn testing going on.

[Edited on 27-10-2010 by dann2]

jpsmith123 - 27-10-2010 at 11:48

Hi Dann2,

Thanks for the update.

Can you elaborate a little bit as to what went wrong during your attempt to make BTO, e.g., the BiCl3 wouldn't dissolve, etc.?

Also let me know if you want to experiment with palladium, maybe I can send you some Pd or PdCl2 if you don't have any.

patsroom - 27-10-2010 at 13:14

Hello, Dann2
Well like I said, the cost is $55.00 USD plus shipping and handling. For international it is possible but one would have to remember custom.
The size of the anodes are 4 inches (101.6 mm) by 4 inches (101.6 mm) of mesh with a coating of about 5/32 of an inch, give or take but should fall within 1.5mm to 2 mm. They have a hanging strap about 2 inches(55 mm) long and 1/2 inch (12 mm) wide.
The ones I have on hand all look good, and I am preparing to test them for my own use. I want to make pre chlorate in one pass from chloride.
They should handle 7.5 volts @ 50 amps well for a few years with care.
For high usage they should be good for 2 yrs. or better but I do not think most people would run them that hard.
Care must be given not to sratch the surface of course,drop, bang or even chip them would not help them very much
.
If there is interest I will sell. These are factory made as I said earlier and I would be willing to sell many as you would like to buy at a time between 1 to 20.
I will watch my U2U messager for anyone interested for awhile.

I do have a Question: Where is Swede I can not find him anywhere?

dann2 - 27-10-2010 at 14:39

Hello,

The Anodes sound like a bargain to me. A great investment no doubt.
But if I were to purchase one of them what on earth would I do with all my spare time?? :D

Swede can be found here:
http://www.amateurpyro.com
I don't know when he posted last. He would be interested in an Anode I would be inclined to think. Perhaps not.
Any chance of a picture?

@jp

The following were painted onto etched Ti and baked at 480C. They all just give passivated Ti which would not conduct any current at all (not even a decaying, slow (few seconds) pulse at the start).

The formula is the same or similar to the 'standard' formula for ATO that is used all over the place in patents and Journal Articles except the Bismuth Chloride and Bismuth Nitrate was used instead of the Antimony Chloride. Ti was etched using HCl.

15ml Alcohol (distilled methylated spirits)
4cc 27%HCl
7.5 grams SnCl4:5H20 (lab reagent)
0.8 grams of 'liquid' Bismuth Trichloride (a liquid that contains 53.16%Bi (made as described below)).
[this is a 15% Bi / 85% Sn formula]

My ATO works OK with this (above) formula using 'liquid' Antimony Chloride made in a similar way to the 'liquid' Bi Chloride and therefor I presumed it would work with the 'liquid' Bi Chloride. It does not.

The formula below was also tried:
15ml Alcohol (distilled methylated spirits)
4cc 27%HCl
7.5 grams SnCl4:5H2O (lab reagent)
1.6 grams Bi Nitrate (Enough Bi Nitrate to give a 21% / 79% Bi/Sn ratio.)
The above is too much Bi as I was aiming for 15% Bi. (bad calculation) but I do not think that is what stoped the
Anode from forming.

I also tried the method of using SnCl2:2H2O by rufluxing the liquid Bi Chloride with the Stannous Chloride for 5 hours (as per my page using
the ATO via SnCl2 method) but this did not work. I got passivated Ti when baked. The precursor became cloudy when let sit for 24 hours with quite a lot of ppt sitting on the bottom (Bi Oxide?)

I also tried refluxing Bi Nitrate with SnCl2:2H2O but the Stannous Chloride reduced the Bi Nitrate and I got Bismuth metal (I presume it was Bismuth metal and not Tin metal?) in the bottom of the rufluxing flask. I did not proceed any further with that precursor.

I will get back to the process this week and have another go at it using smaller percentages of Bi.

I could try putting on an ATO coat on Ti (easy to do) and put on 'BTO coats' on top of the ATO, but I do not think that simply going through the motions of painting on a BTO precursor onto something (in this case an ATO Anode) will simply give you a working BTO coat. The Ti will not be passivated but you will just end up with 'BTO powder' (no good) on an ATO Anode and the Anode will 'work OK' when put into a cell to test it. You would need to test it in a Perchlorate cell to see if it is makeing Perc I guess.
If the above worked then you could simply paint BTO precursor onto say MMO but you may only end up with an MMO Anode with some BTO powder sitting on the MMO and not really bonded/stuck to it in a meaningful way.

I could also try refluxing Bi Chloride (the liquid that I made) with Anhydrous SnCl4 + Amyl Alcohol as per US 3627669 (EXAMPLE 1)(see page). It's using Antimony Chloride but perhaps Bi Chloride may work with SnCl4 (anhydrous).

To make a long story short it appears that you just cannot simply substitute Bi Chloride for Sb Chloride (I am using liquids rem, if that matters) in the 'standard formulas' that I have been using for ATO and expect to get a working BTO coat on Ti.

The patent that put me going on the BTO is US272354. It does not go into detail how the BTO precursor solution was made(example 3). It just mentions SnCl4 (does not state the :5H20 stuff (a solid BTW) but seems? to suggest the Anhydrous stuff(a liquid BTW)) + Bi Nitrate and no acid in the precursor.
Perhaps if I use SnCl4 (anhydrous) + Bi Nitrate + Alcohol it will work OK?????????????
I have no SnCl4 (anhydrous) only SnCl4:5H2O. It a bit of a pain to make involving dry Chlorine gas + Tin Metal.

Perhaps the patents bullshit????????

Reading a completely unrelated patent, US 7494583, near the bottom of columb 12, it shows a precursor formula for an Sn/Bi coating using Bi Oxide + HCl + Anhydrous SnCl4.
Next precursor formula shows an Sn/Sb coating using Sb Oxide + HCl + SnCl4:5H2O.
It seems strange that the Bi doped formula specified Anhydrous SnCl4 and the other (Sb doped) uses the SnCl4:5H2O stuff???
Perhaps only the Anhydrous works with Bi. Seems a bit strange (Dann2 grabbing at straws?? as they add water to the precursor anyways).

The post is a bit of a ramble but I think it conveys my current position!

Does US 272354 demand Anhydrous SnCl4 for the BTO precursor formula???

_______________________________________________________________________
Making Bismuth Chloride:
Bismuth Trichloride from Bismuth metal + Aqua Regia

60cc 35% HCl was added to 12ml 70% HNO3. (an excess of HCl)
20.14 grams (use approx. this amount but weigh accurately) Bi metal consisting of pieces approx. the size of cubic mm's were added.
A very gentle heat was applied to hurry up the reaction. Brown fumes were released and these
must be vented outside as they are dangerously toxic. After approx. 5 hours the reaction slowed
and another 6cc of HCl were added to speed things along. When all the metal had reacted the
liquid was placed on an oil bath at 130&deg; C in order to boil off solvent. When the liquid
was reduced to approx. half volume another 3cc HCl was added to make sure there was no Nitrate
left. The volume of liquid was reduced to approx. 12cc. This liquid was cooled and weighed and found to be 37.88 grams.
This give a percentage Bi of 53.16%. This liquid is used as the source of Bi when making BTO.

Regarding Aqua Regia (from SciMadness)
As long as you keep to the 3:1 ratio (3 of 35%HCl to 1 of 70%Nitric), (maybe add a little bit extra HCl to be sure) no Nitrate will form as it is completely consumed according to;
HNO3 + 3 HCl ==> NOCl(gas) + 2H2O + Cl2(gas)
Nitrosyl Chloride is a gas that boils at -5.5C

__________________________________________________________________

Dann2

Attachment: US7494583.pdf (134kB)
This file has been downloaded 753 times

[Edited on 27-10-2010 by dann2]

patsroom - 27-10-2010 at 15:58

Hello Dann2
Your 100% right, there are those who prefer the hunt and then there are others that would whether just go to the supermarket and get the end results.:D

[Edited on 27-10-2010 by patsroom]

[Edited on 28-10-2010 by patsroom]
I think Swede is lost. He has not been on APC since about 6 Jul of this year. I am starting to worry about him.
Also I can not seem to post my picture here I have one to post but I just tried twice and no results. I have posted over at APC a picture or two.

[Edited on 28-10-2010 by patsroom]

[Edited on 28-10-2010 by patsroom]

patsroom - 27-10-2010 at 16:21

My picture is over size 3.51 mb know wonder I can not get it to post sorry about that. but there are some at APC.
Pat

not_important - 27-10-2010 at 16:47

Try downsizing the photo. If you run Windows, download Irfanview and install. Load the image, Image - Resize/Resample will let you scale it down to fit the 800 pixel max width, Save As a JPEG with a Quality setting of less than 70, which will give a higher degree of compression - you might want to try several settings to chec the results. Or upload it to someplace like tinypic and post the resulting lin.

patsroom - 27-10-2010 at 19:40

http://www.amateurpyro.com/forums/topic/5220-chlorate-cell-s...
if all is right you can go to the above link and find the picture I have been trying to download..........Pat

[Edited on 28-10-2010 by patsroom]

12AX7 - 27-10-2010 at 20:52

You posted a bitmap on the internet?

Open it in Windows Paint. Select Save As. Select File Type, PNG. Save a new file and upload it.

Tim

dann2 - 28-10-2010 at 09:12

Hello,

I think Swede is probable busy flying airplains. He said on APC that he may be busy for a time (in some post or other.) I don't post on APC but read it.

I downloaded the picture from APC, cropped out the actual Anode and reposted below as a JPG.
I'm no photographer BUT a picture of the Anode (not in the bag) would be nice. Go up closer to it and hold camera steady..........

The strap looks a bit thin for 50 Amps but I cannot see how thick it it. 50 Amps into that Anode would be a high current density.



Cheers,
Dann2



LD.JPG - 13kB

jpsmith123 - 29-10-2010 at 09:34

Hi Dann2,

Firstly, with regard to your MnO2 anode experiments.

I've often wondered what would happen if some TiO2 was present with the MnO2.

In the early Beer patent, the TiO2 (or some other valve metal oxide) was considered a critical component for durability and performance. IIRC other patents I've read (DeNora?) mention the use of TiO2 as a "stabilizer".

So I'm wondering, how hard is it to make or buy Titanium Nitrate? What would happen if you added some to your Mn(NO3)2 solution?

Who knows, you might end up with a really rugged MMO type anode with MnO2...maybe it will hold up in a perchlorate cell. Maybe DeNora didn't bother with it 'cause of Beer's patents?

Now onto the #4272354 patent.

This is a mystery. The first time I looked at it, I thought that the wording of the first paragraph under example 3 was somewhat ambiguous, and that maybe they were still using the MMO precursors too, with the only change being the substitution of the Bi Nitrate for the Chloride, for some reason.

But the text of the following paragraphs clearly seem to imply that example 3 has no MMO stuff.

So, based on your results, I'm tempted to say that the patent is simply wrong for some inexplicable reason.

This conclusion seems to be supported by the fact that the other patent you cited, 7494583, implies that an anti-passivation layer is necessary between the Ti substrate and the SnO2-Bi2O3 outer layer.

If it were me, I would try, as a first step, putting the Sn-Bi oxide mix on over something else, just as a test to see - does it make perchlorate? If it does, then it might merit serious further experimentation.

dann2 - 29-10-2010 at 11:00



What temperature does Ti Nitrate decompose at. It would need be at or below 400C as you cannot (I believe) go above that temperature when making MnO2 Anodes.
Ti Tetrachloride is usually used when making MMO stuff and Ti02 is wanted in the coating. I don't know what temperature it need to go to to form TiO2.

I can try putting on a 'coat' of BTO on top of ATO. (or on top of MMO), but simply making up a precursor of BTO (using SnCl4:5H2O + Bi Nitrate (or Chloride) + Alcohol + (perhaps) some HCl) painting and baking may simply give a coating of powdery BTO that not really a useful viable coating.
Anyhow I am currently looking for Anhydrous SnCl4 to see if that will work (for BTO) on bare Ti. (as per US 3627669, Example 1)
It's an ATO patent but this method may work with BTO.

Dann2

Rosco Bodine - 29-10-2010 at 12:42

Let me make sure I have this straight. The patent says an anti-passivation interface layer is required for a Ti substrate ???? ..... hmmmm ....now there's a revelation huh, .....I mean, ........who woulda thunk it ? :D

Alternately to ruthenium....maybe cobalt or (even better) nickel-cobalt spinel
could be good for that "anti-passivation interface" for a Ti anode substrate.

Then, over the "anti-passivation interface" the patent says a sealing layer is needed ....another huge "revelation" huh.

How about a syrupy Pytlewski type polymer / or tin methanolate in methanol like the precursor used for the spun ATO fiber ? Or alternately .....

How about an ammonium bismuthate / ammonium stannate sol thickened with 100% hydrolyzed PVA which has a detailed process description ?

As for adding a Ti oxide component to a coating mixture, a Ti alcoholate might be useable in an anhydrous precursors mixture. It may be possible to form the alcoholate of Ti in a similar way as is possible for making an aluminum alcoholate, via an amalgam. Pieces of freshly cleaned and etched Ti are dropped into the anhydrous alcohol containing a small amount of HgCl2 and the Ti alcoholate should form from reaction of the alcohol with the elemental Ti dissolved in the film of amalgam, the reaction continuing with evolution of hydrogen split off from the alcohol as it reacts, with the amalgam dissolving more and more of the Ti as the reaction proceeds until the Ti is completely consumed and a few droplets of mercury remain as a residue, along with any Ti oxide which may be byproduct of reaction with any moisture. The anyhdrous alcohol solution of the Ti alcoholate
can be decanted or filtered off from the residue. This Ti alcoholate may be miscible with other alcoholates of Tin and Bismuth for example or with their alcohol suspended sols. I do not know if the titanium oxide component may
also form a stable hydrosol or peptized aqueous colloidal suspension, but it very well could form at least a temporarily stable hydrosol. A Ti oxalate or tartrate or acetate, citrate are other potential possible precursors.




jpsmith123 - 29-10-2010 at 13:29

As far as adding some TiO2 to the MnO2 is concerned, IIRC the only Mn compound known to decompose to beta-MnO2 is the nitrate, right?

So to add TiO2, I guess we have to find a soluble Ti compound that thermally decomposes to TiO2 and is compatable with an alcohol solution of Mn(NO3)2.

I read somewhere that Titanium Tetranitrate Ti(NO3)4, CAS 12372-56-4, is used to make thin films of TiO2 and that it's highly soluble. So it might be a good candidate, but it seems hard to find and apparently it's hard to make?

I wonder if Titanium Ethoxide would work? Can it be bought inexpensively?

Rosco Bodine - 29-10-2010 at 14:29

The decomposition of many different compounds would lead to the oxide and the carbonate does it pretty easily. The nitrate probably decomposes most easily to the oxide but many other compounds are also valid precursors. Tartrates and oxalates tend to have reducing properties during decomposition because of the byproduct carbon monoxide during pyrolysis. In mixtures where the idea is to limit the oxidation state for the Ti oxide so that a conductive suboxide or doped oxide (mixed oxide) is formed, then tartrates and oxalates, perhaps acetates and citrates or chelated metal compounds could have usefulness. Alcoholates are used for similar reason, the carbonization during pyrolysis tends to have a reducing effect on the deeper layers while there is complete oxidation of the surface layer from atmospheric oxygen. Nitrates definitely can be made from
Zirconium, Titanium, Tin and Bismuth but these type compounds are unstable and highly reactive ....you don't just dissolve them in water and get solutions of the nitrates but you get products of hydrolysis, precipitates or sols depending upon pH and concentrations, temperature, ect. Dissolve in alcohols and the reactivity leads to alcoholates or "alcholosols" colloidal suspensions of the oxide in the parent alcohol. Some such systems may be only quasistable transiently stable precursor "paints" which won't keep for use longer than minutes to hours, they may be "reactions in progress" from the moment they are made, as opposed to being stable solutions. The mixed precursors may react with each other as well as undergoing decomposition by themselves or interaction with the solvent.

It is precisely this problematic instability, reactivity and interactivity which is causing problems with formulating precursors mixtures evident in some of the described experiments.

If titanium nitrate forms a stable solution with water, then it should form from
amalgamated Ti metal in moderately diluted HNO3. The amalgam should nullfiy
the usual TiO2 passivation layer, and the HNO3 would react with the nascent
Ti(OH)2 simultaneously oxidizing the Ti with formation of the Ti(NO3)4.
However only TiO2 would result from the pyrolysis of the oxidized +4 Ti ,
therefore the nitrate could not be expected to operate as precursor for any
content of desired TiO or conductive Ti "suboxide", as would be the case for
an Ti salt of an organic acid in an anhydrous solvent.

Amalgamated Ti in a glycerin solution of Bi nitrate could also lead to compounding between the Ti and the Bi or likewise for interactivity of their alcoholates, forming Bi titanate or Ti bismuthate (exist?) .....so there is no simple predictability what will or may occur. There could even occur a "gilding" of metallic bismuth/titanium/mercury "alloy" as a penetrating surface layer attaching to the Ti substrate, becoming sufficiently loaded with Bi that the reaction then stops at an undetermined depth. Such a substrate upon baking might form a viable anode substrate, after volatization of the mercury and pyrolysis of the mixed Bi and Ti oxide "interface" layer which may be an effective anti-passivation layer. Similarly other doped Ti oxide using other metals for the "gilding" alloy could also lead to anti-passivated Ti anode substrates upon pyrolysis.

All of those "unknowns" should have dann2 running towards
ammonium stannate - ammonium bismuthate - PVA as a precursor mixture having validity and stability.

That would presently be the most promising "problem solver", unless of course the goal here is "redefining the problem" rather than solving it.

Sorry, I just get the feeling I am talking to a brick wall. Some patents are better than others at revealing anything about the chemistry involved. Coating precursors that are not described in detail and are not claimed as a specific process and formulation by a patent does not necessarily mean that the more pertinent subject matter of the patent has no validity, the precursors for the coating being beyond the scope of the subject matter of an invention being covered by the patent claims. The chemistry of the precursor materials is a technical aspect which has greater importance than does an oversimplified description of the precursors which is found in any patent that may be deliberately vague about exactly how the coating mixture was prepared.

[Edited on 30-10-2010 by Rosco Bodine]

jpsmith123 - 1-11-2010 at 16:22

I can't seem to find out much about Ti Nitrate, e.g., at what temperature does it decompose.

And I couldn't find it for sale anywhere off-the-shelf except in some ultra high purity grade at Sigma-Aldrich, IIRC.

I did read that TiO2 will dissolve in hot HNO3 so that's a possibility.

As far as Ti alkoxides are concerned, that might be the way to go. I don't have any of the patents in front of me, but I think Beer used them in his examples.

Anyway, according to Wikipedia:

"Many alkoxides can be prepared by anodic dissolution of the corresponding metals in water-free alcohols in the presence of electroconductive additive. The metals may be Co, Ga, Ge, Hf, Fe, Ni, Nb, Mo, La, Re, Sc, Si, Ti, Ta, W, Y, Zr, etc. The conductive additive may be lithium chloride, quaternary ammonium halogenide, or other. Some examples of metal alkoxides obtained by this technique: Ti(OC3H7-iso)4, Nb2(OCH3)10, Ta2(OCH3)10, [MoO(OCH3)4]2, Re2O3(OCH3)6, Re4O6(OCH3)12, and Re4O6(OC3H7-iso)10."

So is it possible that Dann2 could just take his Mn(NO3)2 in alcohol solution, stick a piece of Ti in it, and anodically dissolve the Ti?

Rosco Bodine - 1-11-2010 at 17:46

The amalgamation method which I suggested would possibly be a simpler, easier and more direct approach for Ti isopropoxide, which has similarities in its chemical properties with Al. I have been able to find nothing so far in early searching for any description of Ti amalgamation, so this idea may or may not work. No experiment has been done by me to confirm this idea, Ti is a peculiar material in its reactivity. Under very specific conditions it can be reactive, and when the conditions are changed even slightly it is passivated. So the help provided by an electric potential
to force it to react may ultimately be required. Referencing the industry corrosion data for Ti shows a 3% HCl at boiling point attacks Ti very well, but increasing to 5% HCl the rate of attack is reduced forty fold towards passivity, and a similar effect occurs for reduced strength below 3% HCl. Therefore, there is a kind of 3% window concentration for the HCl where the attack of the Ti is effective according to the industry corrosion data found on the following page.

http://www.titaniumprocessingcenter.com/titanium-corrosion-d...

If (and that is a big "if") the Ti can be amalgamated in an aqueous solution, it would probably be a good starting point to try etching the Ti with boiling 3% HCl and adding HgCl2 to the hot solution after the Ti has been etched for awhile by the 3% HCl. If the Ti does amalgamate, it should be visible as an effect of mirroring and/or increased evolution of hydrogen. If the amlagamation is successful then the solution can be poured off quickly and the isopropanol introduced for production of the isopropoxide, or dilute nitric acid may produce the nitrate. That's another unconfirmed
possibility. I have gleaned a bit more information about Ti amalgams and one patent stated that the solubility of Ti in Hg is low, on the order of 5% and that the Ti is prone to "dewetting" by the amalgam. Also there are formed at high temperatures intermetallic compounds Ti3Hg and TiHg.
There are possible complications then due to a potential self-limiting effect of the attack of Ti by the mercury even when Ti is wetted, where the amalgamation may not progress in increasing depth at a good rate. However, if the amalgamated Ti is high fired in an inert or reducing atmosphere, a spongy porous sintered Ti surface structure
is left behind when the mercury vaporizes. This could be a potentially useful substrate surface treatment for creating a rough surface that would retain dopants for the interface which could be left physically entrapped in the porous structure. Potentially this could be an ultimate kind of surface preparation for a Ti substrate, where the surface is to a limited depth transformed into a rigid yet porous structure that is integral with the solid Ti substrate.

The conventional and published descriptions for preparation of Ti isopropoxide involve reaction of TiCl4 with isopropanol.

The isopropoxide of Al forms very actively and vigorously from clean and etched Al in anhydrous isopropyl alcohol, to which some HgCl2 is added (perhaps 1% to 2% the weight of the Al or Ti), hydrogen being split off from the hydroxyl of the alcohol as it is replaced by the Al, actually 3 of the isopropyls per atom of Al. Ti should work the same way only there will be 4 isopropyls as a result of the +4 Ti versus +3 Al. Hydrogen gas is evolved profusely and the reaction is exothermic, could even boil the excess of alcohol from heat of reaction, so a capacious vessel should be used. The alkoxide is air and moisture sensitive. In fact there will be some insoluble precipitate of TiO2 possibly even as a gel from the reaction and decomposition of some of the isopropoxide being formed until the alcohol present is rendered completely anhydrous, as there will always be some trace moisture present in the alcohol.

Glycerin and ethylene glycol are other potential alcohols which may be useful. Bi nitrate forms an alkoxide with glycerin and with other polyhydroxy alcohols which may possibly be a compatible dopant scheme in sol-gel processes for Ti alkoxide. The Ti alkoxide is going to be a lot more moisture sensitive than the Bi nitrate / alkoxide. Lowering the pH with HNO3 could help keep everything in solution if a soluble Ti(NO3)4 does form.

Anyway, a much simpler approach which should work for producing an anti-passivation conductive interface of Co-Ni spinel and sealing that interface with Bi doped SnO2 has been suggested by information gotten from a pretty extensive survey of the literature, broader than just the anode patents. And given the fact it became evident a long time ago that the patents don't tell the whole story, I have more confidence in proposing a different approach gotten from combining the specific information about compositions that are best for doing specific things.

It is like putting together a tactical rifle where the barrel may be made by Hart, the stock and bedding by Accruglas, the action by Sako, the trigger by Canjar, and the micrometer mount by Buhler, and the scope by Nikon, and so on ....you put the parts together to build the system you want.

That spun fiber DTO patent gave me an idea that it may be possible to blend the fibers of DTO maybe 70% DTO fiber with 30% borosilicate glass fiber or glass powder, perhaps blended in suspension in stannous fluoride, drained, dried, compressed at high pressure and sintered under high heat and pressure into a ceramic / glass composite anode. There was some discussion about a ceramic substrate anode and this is a similar idea. Particles of a catalytic material could also be entrapped and sintered into the fibrous structure.
Something like this could represent a new state of the art.

http://www.youtube.com/watch?v=hqzDqF1VF38&fmt=18 Glenn Miller tribute - Moonlight Serenade - Carly Simon

[Edited on 2-11-2010 by Rosco Bodine]

dann2 - 24-11-2010 at 11:44


Some Ti info.

Attachment: titanium.pdf (420kB)
This file has been downloaded 1534 times

Manganese Dioxide on Ti

dann2 - 1-12-2010 at 18:02

Hello Folks,

I have been running a number of MnO2 Anodes in various cell for the last month or so to see how they perform.
All Anodes consist of five coats (and five bakes) of the same MnO2 percursor solution (approx. 50% Mn Nitrate
solution in water) baked at approx. 390C on etched Ti.
One Anode had 2 coats of Co Oxide put on first.
All Anodes were run under similar current desity of 50mA per square cm and had a similar Cathode arrangment.
2.5 Amps into one litre cells with temp. in the twenties C.
I have come to the rather bizarre conclusion that the MnO2 Anode performs much better in Potassium Chlorate cells
compared to Na Chlorate cells. Also Co Oxide undercoat is not required and seems to be an actual disadvantage.

The MnO2 on bare Ti run in a Na cell (no pH controll) give 28% CE (current effeciency) and lasted 30 days.
The Sodium pH controlled Chlorate cell that I ran (still running actually) using MnO2 on bare Ti
give only 52% CE for the first ten days and has been going now for 28 days so far with more to go .
The Anode that had the two coats of Co Oxide as a first layer (+ five coats of MnO2 on top) had the shortest run time
of only approx. 20 days and give 26%CE in a non pH controlled Na cell.
The liquor coming from the Na cells was a rather ugly brown colour but most of this settled to the bottom after some
days but its very hard to pour off the liquid without stirring up the brown ppt. The liquid left had a yellow colour.
Any pink colour that did appear in the Na cells after a day or two of operation give way to the brown colour after approx. five days.

With my K Chlorate cell (non pH controlled) I am getting a high CE% (at least 56%, have still to dry the product that I have removed)
for the first 9 days of running. Lots of Chlorate on bottom of cell. The liquid is a very clear pink colour and there is little (but some)
discolouration in the raw Chlorate. This cell is still running.

Will run a pH controlled K cell when I get a free power supply.


Dann2

avi66 - 23-12-2010 at 13:43

i bought a new 2 mmo anodes which design for chlorate manufacture, i want to use one of them as a cathode in my non-ph controlled k chloride cell .... is it destroy the anode coating and i will stay with bare ti ? or is it work ? and if it work as a cathode, what is the anti-chlorate reduction potential ?!

i got an idea of a process of easy manufacture mno2 anode....
if we take bare etched ti metal, put it in mn(so4) 90g 500ml water, 90c, 12ml conc h2so4, at current density up to 10ma/square cm, as in nurdrage video, and then burn the thick mno2 electrolytic coat with heat gun at 380c, we will convert all the thick coat of mno2, to the beta-mno2 ... then we will receive a thick strong coat of beat mno2 ?!
thanks for the helpers, hope to get your opinion on my technique idea of mno2 anode manufacture.

dann2 - 24-12-2010 at 16:35

Hello,

A good way do find out how the Pb/Ag substrate would hold up in a Perchlorate cell (or Chlorate) would be to make a small amount of the alloy and cast an Anode. Use this Anode in a Perchlorate cell and see how long it lasts. If it lasts quite a long time, like MMO or Tin Oxide on Ti then it will ge OK for a substrate.
If it erodes like Graphite then it will not make a good substrate and will be comparable to Graphite as a substrate. It will need a perfect coating of Lead Dioxide which is not good in the Amateur world.

dann2 - 24-12-2010 at 17:28


Did you purdchase the Anodes or make them


I think MnO2 will strip off if used as a Cathode. The bare Ti is OK as a Cathode.

You cannot put on a thick coat of MnO2 using electricity (plating) as it peals off as Nurdrage said.



avi66 - 25-12-2010 at 02:37

thanks for the information about the mno2 anode... now i will not try this experiment for nothing.
i bought some ruthenium based mmo anode, now i wonder how could i remove the coating, soo i will be able to use the titanium beneath as a cathode ?

dann2 - 25-12-2010 at 17:46

Hello,

You can use MMO as a Cathode if you want as they use it as a Cathode in Bipolar cells in industry (cells where a sheet of MMO material is a Cathode on one side and an Anode on the other side). It sounds like a terrible waste IMO. Purchase Ti as it should be cheaper than MMO and use that as a Cathode or just use good stainless steel as a Cathode.
Keep Cathodes small and this will help to stop Cathodic reduction (or use additives).

BTW I posted the first post above in the wrong thread!!!!!!!!!! (O dear)

Dann2

Xenoid - 25-12-2010 at 18:24

All the pool chlorinator electrode assemblies from around here are now wholly manufactured from MMO. This is because they are all self cleaning now, so that the electrode polarities are switched back and forth regularly to stop build-up on the cathode. This also simplifies construction and inventory for the chlorinator companies as they don't need to worry about plain Ti electrodes.

I am currently running a 5 litre chlorate cell with an all MMO 10 element pool chlorinator electrode. I switch polarity two or three times per run at which time any whitish "crud" that has built-up on the cathode immediately flakes off when it becomes the anode.

Incidentally, I now note most companies are switching over to solid plate electrodes rather than mesh, they last longer I guess.

MMO is now so cheap and common :D

tnphysics - 30-12-2010 at 23:56

Ti is corroded by:

-Strong base (forms Ti(OH)<sub>6</sub><sup>2-</sup>;)

-Fluoride + acid (forms TiF<sub>6</sub><sup>2-</sup>;)

-VERY strong acid + water (forms TiO<sup>2+</sup>;)

-Anhydrides of strong acids (same)

-Strongly acidic, highly reducing conditions (forming Ti<sup>3+</sup>;)

It passivates under almost any other conditions. The chlorate cell without pH control is probably the first such condition, as the pH can become very high. With pH control, there should be no problem. Is this what has been observed?

[Edited on 31-12-2010 by tnphysics]

avi66 - 6-1-2011 at 16:21

the mixed metal oxide anodes, corrode more as a cathode or a anode ?

[Edited on 7-1-2011 by avi66]

dann2 - 10-1-2011 at 12:52

Hello,

Running some MnO2 Anode cells. There is a marked contrast between Na and K cells. Still running the K Chlorate (no pH controll). If the Voltage accross the cell is anything to go by the Anode is going to last approx. 80 days. (5 coats MnO2)
A similar Anode only lasts 30 days in an Na cell and gives half the CE.

I cannot get the table to post.

Still to run a pH controlled K cell.


MMO will corrode more as an Anode IMO. I am beginning to wonder do those bipolar Anodes (picture way above from a guy who works in the industry) have MMO on one side of the plate and perhaps bare Ti on the other side?

I had Ti corrode when I had Fluorine in a cell that had a Lead Dioxide Anode in it with the Ti exposed in places.
Ti will also corrode if a stupidly high Voltage is applied to passivated bare Ti.
I have never heard of anyone having Ti corrode in high pH chlorate cells. It does make a difference if you put the Voltage to bare Ti suddenly.
If you put a piece of bare Ti into a (say) Chlorate cell and connect (approx. don't remember the exact Voltages) 12 Volts to it you might well get current flowing in places and erosion of Ti. But if you were to connect a similar piece of Ti to the power supply at 2 Volts and them raise the Voltag slowly (say one Volt per sec) then you may have to go to 15 or 16 Volts before the corrosion starts. The TiO2 layer I guess gets a change to thicken with the slower rise of V

"MMO is now so cheap and common :D "

:) Shouldn't be allowed

Dann2



[Edited on 10-1-2011 by dann2]

gregkdc - 20-1-2011 at 09:28

Hello everybody I am a complete noob to making chlorates/perchlorates and I have been studying it for a few weeks now. I am very active in armature rocketry so obviously the end product that I would like to make it AP. I have been reading about the lead dioxide anodes as well as platinum for perchlorate production, and I would really like to avoid using lead all together and we know the price of platinum is a problem. So that leaves me with very few options, one is thermal decomp of chlorate to perchlorate or to try to use graphite in a diaphragm type cell. I was wondering if anybody has ever tried using silicon for an anode? For chlorate production I am going to try making a magnetite anode in a microwave. I found an interesting webpage for melting metals in the micro wave and the material that is used to heat the kiln is magnetite. The author states that he has gotten it hot enough to melt the ceramic refractory he was using so it should be able to melt the magnetite. I also have some powdered silicon that I bought for pyro purposes and was thinking of making a silicon/magnetite alloy for the anode if I can get it to melt in the microwave. Any thoughts would be appreciated.

gregkdc - 20-1-2011 at 14:04

In my previous post disregard my idea of mixing silicon with magnetite (sounds like a potential thermite reaction) and if it is not that violent of a reaction I am sure they would react at hi temps. Maybe another metal oxide would work with magnetite for perchlorate production. Anyways I will attempt to move forward with a microwave magnetite anode for chlorate production and try converting this to perchlorate via thermal decomposition.

On a side note I read somewhere that magnetite can be used with lead dioxide for a perchlorate anode. I am not planning on electroplating an anode, but was wondering if you could simply place a magnetite anode in the bottom of the cell so it is lying horizontally on its side, and add a thick layer of free lead dioxide powder on top of the magnetite anode. The lead dioxide is conductive (more than the magnetite) so it should allow some of the current to pass through it and make perchlorate with some obvious loss in efficiency. Has anybody tried something like this?

Xenoid - 20-1-2011 at 14:11

Quote: Originally posted by gregkdc  
Hello everybody I am a complete noob to making chlorates/perchlorates and I have been studying it for a few weeks now. I am very active in armature rocketry ....


Yeah, yeah we've heard it all before!

"armature" rocketry, eh..! Is that some sort of new electromagnetic propulsion system :D

I suggest you have a look at this video;
http://www.youtube.com/watch?v=HJVOUgCm5Jk

and read this item;
http://en.wikipedia.org/wiki/PEPCON_disaster

You want to make ammonium perchlorate and you're worried about a little lead :o

I've been making chlorates and perchlorates for several years and I'm still reluctant to make ammonium perchlorate. You'll need good chemical skills and more than "a few weeks study" before embarking on this task. I suggest you stick to nitrate based propellents, they're a little more forgiving!

gregkdc - 20-1-2011 at 14:51

Thanks for the welcome, but I fear you are already too late for me not getting involved with AP (at least purchased AP). The irony is that in some ways I would rather stay with nitrates but nitrate based propellants, even though they are less energetic and reactive, are considered explosive while APCP is not. That means I would have to get a LEUP and all of the federal intrusion to move into larger nitrate motors or make AP motors. Also it is not that I really fear lead I could make a go of it, but from what I have been reading the reward is fleeting and as a whole it does not seem to be worth the potential risks. Just my opinion from a guy that has zero experience that is why I am here to get some advice from the experts.

PS the pepcon disaster is quite an impressive blast!

Xenoid - 20-1-2011 at 16:04

Quote: Originally posted by gregkdc  
... but I fear you are already too late for me not getting involved with AP (at least purchased AP). ...


Oh well, I tried.

Stick to buying professionally manufactured ammonium perchlorate, it will be safer, probably cheaper and a whole lot less of a hassle in the long run!
It's the possibility of ammonium chlorate (highly unstable) contamination in the home made product that worries me, not the AP per se.
There are lots of anode threads in Sciencemadness, and many ideas have been tried, you'll need to do a lot of searching and reading. Unless you are specifically interested in investigating the chemistry involved in the various electrolytic and coating processes, it would be best to stick with purchased MMO anodes for chlorates and platinum/Ti for perchlorates.
A cheap thermal coating of beta-MnO2 on an MMO anode will also allow you to make perchlorate, albeit with a little permanganate contamination to clean up.

hissingnoise - 21-1-2011 at 06:27

Quote: Originally posted by Xenoid  
I've been making chlorates and perchlorates for several years and I'm still reluctant to make ammonium perchlorate.

The easy way to AP is metathesis with NaClO4 and a NH4 salt . . .
AP immediately precipitates when the solutions are mixed!
I used NH4NO3 as NaNO3 is useful.
For high purity AP, NaClO4 can be reacted with HCl, filtered and heated to drive off HCl . . .
The HCLO4 produced this way can be practically free of Na!


gregkdc - 21-1-2011 at 15:12

OK Xenoid I will take your advice and buy AP for now, this was pretty much what my plan was anyways, but you know this type of thing will drive me crazy until someone makes a good anode.
I have been reading through most of the anode threads and I can see that the majority of the topics relate to electroplating various oxides, and then such anodes fail due to the oxide layer breaking off or being eroded down to the substrate.
Has anybody tried making massive anodes that would be chemically solid? In particular making a magnetite type anode by melting the material instead of thermal decomposition or electro-plating. From what I have read the magnetite anode seems to have remarkable corrosion resistance and I can't help but wonder if it is from the way it is manufactured. Sure, electro-plating may be the way to go for industry because it is cost effective for materials but maybe it is not the way to go for the armature. I am particularly interested in seeing what would happen if you melted cobalt II,III oxide into an anode. It decomposes when it melts but from web sources the reaction appears to be in equilibrium with ambient oxygen so the end product can be either cobalt II or III depending on if the environment is oxygen rich or starved. So the questions is would you be able to create an atmosphere that would have the proper amount of oxygen that would keep the original II,III oxide in equilibrium? Also if this doesn't work I wonder if a eutectic mixture of something like bismuth oxide could be used to get it to melt at a temperature lower than the decomposition temp of cobalt II,III?

Xenoid - 21-1-2011 at 18:42

Quote: Originally posted by gregkdc  
OK Xenoid I will take your advice and buy AP for now.....

Has anybody tried making massive anodes that would be chemically solid? In particular making a magnetite type anode by melting the material .....


Good! I believe the professionally made AP has a specific grain size distribution that is required for rocketry. This is also hard to achieve by amateur producers.

Yes! Yes! It's all been tried, but we would welcome any input you care to make.
There is a section at dann2's web site pertaining to his efforts at making massive magnetite anodes;

http://www.oxidizing.110mb.com/chlorate/anodes.html

Go to the magnetite anode section, and near the bottom are two links.

If you haven't checked out his site previously, it might be worthwhile you doing so!

I don't believe anyone has tried a massive Co3O4 anode, I don't think it's readily available (Co3O4, that is). I think it is even worse at making perchlorate than magnetite :(

If you do experiment with making anodes and chlorates and perchlorates, whatever you do, don't try electrolysing ammonium chloride, it will produce extremely sensitive and highly explosive nitrogen trichloride. Skilled chemists have lost fingers and hands with that :(


tnphysics - 25-1-2011 at 14:13

What about using electrolysing lead chlorate (to make perc)? This should form a PbO2 layer at the anode and a Pb layer at the cathode, protecting the substrate. Keeping lead in the solution should maintain this layer. The solution will drift acid, and will eventually cease making PbO2. The cathode will need to be replaced at this point-Pb is terrible at making hydrogen, which is what we want in this case.

Also, what about Ti in a ph-controlled cell?

Au is probably great for perc, if Cl- is absent.

dann2 - 11-2-2011 at 15:11

Hello,

Been running some Mn Dioxide Anodes in various cells to see how they performed. The star performer seems to be a
MnO2 Anode in a non pH controlled Potassium Chlorate cell. The Sodium cells give disappointing results for some
reason or other. The SS Cathodes seem to corrode more in Na cells too.
All the Anodes has 5 coats of Mn Nitrate solution except the Anode that had two coats of Co Oxide first + five coats of Mn Nitrate on top.
This is a light coating of Mn Oxide IMO. I don't know if having 10 coats is twice as good as having five (etc) but five certainly give a good working Anode.
Forget the Mono metal spinel (Cobalt Oxide) IMO as it's a waste of time.
I regret not running the pH controlled K cell at an Anode CD of 50mA per square cm (like all the rest). I ran it at 80 to hurry things along but if failed much sooner than expected. One liter cells are a bit too small for pH controlled cells as you have to change the liquor too often and the cell spends a lot of time in 'start up' mode (adding lots of extra acid to get pH to go where you want it).
How would one identify the brown gunk that is suspended in the cells. I suspect it is coming from the Cathodes.
I hope to run another pH controlled K cell (50mA/cm^2 Anode CD) with Ti Cathodes to see if they run any clearer.
I weighed the brown gunk (dried) from a cell run and it was 2.33 grams. A small amount of material that is able to turn the solution completely opaque brown.
I attach all and every gruesome detail. What do you's think of the colour scheme?

Dann2

Attachment: mno2.zip (95kB)
This file has been downloaded 658 times

dann2 - 2-3-2011 at 14:57

Hello,
The Manganese Dioxide Anode finally give up the ghost after 97 days! @ 50mA per square cm. It was working in a non pH controlled Potassium
Chlorate cell. There was a total of five liquor changes, the fifth change was on day 98. The cell Voltage on day 97 was around 7 Volts. It fell just below 7 Volts after liquor change but then started to rise. A few days later the Voltage was 10 Volts. The CE was good during the last run (day 77 to day 97) at 47%. Average for the 97 days was about 47%. The liquor was clear for most of the last run with some brown stuff appearing towards the end.
The Anode was run at 2.52 Amps which gives a total of 2100g of K Chlorate formed. It's a fairly small Anode.
Perchlorate was inclined to appear in the cells as detected my Methylene Blue.

Dann2

12AX7 - 7-3-2011 at 09:12

Found something quite interesting today,

http://www.dextermag.com/upload/TDK_Dexter_Ferrites_Electrol...

Perhaps some samples can be tested. And what do you know, spec'd for corrosion resistance in NaCl solution, albeit dilute.

Tim

hissingnoise - 7-3-2011 at 10:37

Right, now where are those old radios?
Magnetic anode-sludge is a cut above fine graphite for starters . . .
Long time no, er, read, 12AX7!
Welcome home!

hissingnoise - 7-3-2011 at 10:54

Ahem! Post Harlot crown slipping somewhat . . . ?

;)

tnphysics - 9-3-2011 at 15:10

Why does ClO- + 4OH- -> ClO3- + 2H2O + 4e- not occur in a non pH controlled cell?

tungsten anode

symboom - 20-4-2011 at 21:43

tungsten from an TIG electrode
coatings are
mine i have is orange thorium oxide up to 4%

tungsten alloys

Green None
Gray ~2% CeO2
Black ~1% La2O3
Gold ~1.5% La2O3
Sky-blue ~2% La2O3
Yellow ~1% ThO2
Red ~2% ThO2
Violet ~3% ThO2
Orange ~4% ThO2
Blue ~2% Y2O3
Brown ~0.3% ZrO2
White ~0.8% ZrO2
which one would be best at handling as an anode
tungsten is resistant to oxidation, acids and bases at normal temperature Ive read somewhere an experiment making chlorate replacement for platinum but it does not say much just that it was abandoned when they heard of lead dioxide anodes
http://en.wikipedia.org/wiki/Gas_tungsten_arc_welding

dann2 - 9-7-2011 at 09:02

Paper attached on Diamond Anodes.



Attachment: diamind.pdf (804kB)
This file has been downloaded 829 times

dann2 - 13-7-2011 at 15:25


Hello,


Slightly off topic but since this thread is mostly about making Anodes for Chlorate and Perchlorate........

The Chlorates and Perclorates.
Naval report. Size is 20Mb
Lots of data about Chlorate and Perchlorates

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=AD242192&Locatio...

Thanks to the Wizard.

Dann2

dann2 - 2-8-2011 at 08:39

Another one for the Sodium Chlorate making guru's.
Thanks to Potassium Mn04 for that one.

Dann2

Attachment: TES000093.pdf (429kB)
This file has been downloaded 1583 times

White Yeti - 3-8-2011 at 06:53

You mentioned palladium, but palladium, from what I understand, is even more expensive than platinum.

the mentalist - 3-8-2011 at 10:59

Hello,

Alright, that was a long thread to read. So on my long quest of making APCP I have successfully made only the aluminum:( so my question, request for help/advice has to do with the synthesis of ammonium perchlorate, More so about chlorate and perchlorate cells, considering that every route leading to ammonium perchlorate uses sodium chlorate and some type of (per)chlorate cell. So I'm more than prepared to start at the bottom and do my research before I get any final product. With that said, my first cell I want to construct will be making sodium chlorate from sodium chloride. So i guess I'm just looking for advice on the steps I should take to construct a cell. Like what I should use for the cathode and anode, what concentration of salt should be in the water, does it have to be air tight? Any advice it awesome!

And please don't try to scare me off, I'm in this for the long haul, thus I'm willing to do my research and am not afraid to work with lead.

[Edited on 3-8-2011 by the mentalist]

Also what are your thoughts if I was to buy a mmo anode, rod sheet or mesh?

[Edited on 3-8-2011 by the mentalist]

Xenoid - 3-8-2011 at 11:46

Quote: Originally posted by the mentalist  
... thus I'm willing to do my research ...


Hah! Clearly you are NOT! Otherwise you would not have made this post!

There are literally dozens and dozens of threads on chlorate and perchlorate making on this forum alone. As well as several books and manuscripts available to download!.

Also, check out dann2's site, if you haven't seen it before you have clearly done no research at all!

http://www.oxidizing.110mb.com/

Bismuth Metal Oxide Pyrochlores As Electrode Materials For Electrolytic Ozone And Perchlorate Generation

jpsmith123 - 4-8-2011 at 10:43

Here's an interesting patent.

Attachment: WO2010148107A2.pdf (418kB)
This file has been downloaded 713 times

dann2 - 5-8-2011 at 13:49


Thats in interesting one. If Sn could be got to work instead of Ru it would be very cheap.
1200 degreese C is needed though. You would have to make a rod of the stuff and hope the salts being conducted up the sintered rod would not be too much of a problem messing up the connection at the top.

Dann2

jpsmith123 - 5-8-2011 at 16:33

I wonder if you would really need a stoichiometric Bi2Sn2O7 pyrochlore?

Or if just a solid solution of Bi2O3 with SnO2 (or with TiO2 for that matter) would work?

Maybe the take home message is that Bi2O3 is the critical oxide for perchlorate? And if you have Bi2O3 + SnO2 you have the De Nora patent, and if you have Bi2O3 + TiO2 you have one combination that seems like it's missing from Beer's patents?

BTW here's a paper that goes into detail on making Bi2Ru2O7. What's interesting is the sol-gel method they use where they dissolve Bi2O3 in a citric acid + ethylene glycol solution then they add RuCl3 and fire it. That method might work with SnCl2 and/or SnCl4. Who knows, maybe it wouldn't passivate your Ti substrate.


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[Edited on 6-8-2011 by jpsmith123]
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