More on PbO2 electrodes

Well guys I think i've hit the jackpot. Still not sure though.
I took a piece of Ti, made some pitts in it with a hammer, plated with silver untill the holes were full, sanded the Ti untill the silver was only in the pits, plated with alpha PbO2 after that with beta PbO2.
I tested it for 40 minutes in a NaCl solution with 4 amps, the current dropped a bit but i believe that it was because of bad contacts and evaporation.

Ill check it in a full NaCl to NaClO4 cell and then ill post the results, Ill check one mole.

I belive that this concept of mine will work

Sorry for no images .. they will come if the anode will be proved to produce perchlorate

Silver (Per)Chlorate

I already discussed the silver issue with dann and explained to him that because both silver chlorate and perchlorate are soluble and the chloride is not soluble there si no risk at all.

anode update: thje lead dioxide coating wasnt adherent enough and it passed away ./ the dioxide just peeled off. I belive that next time ill have to make holes through the Ti this is very important.

question: what can i use as a surfacant to avoid bubles? I have never seen those matters that dann explains in his site, maybe there is a more common name to those surfacants? where can I get them?

Stannic Chloride (Hens teeth)

Hello,

Someone spending large amounts of time and cash on chemicals and equipment.... wonder who that is ?

Moving swiftly along...........

Did you obtain any details of thickness of Pt coating on Ti?

What sort of conditions are you using it under and is your Chlorate (I am presuming you are starting with Chlorate or are you starting with Chloride and going all the way to Perchlorate) totally free from Chloride.
Are you using an additive like Dichromate?

Of course if you get bored making all that Perchlorate you can always use it as a substrate for a ..........

Cheers,
Dann2

Hello,

Do you mean to use Palladium Oxide as an undercoat between the Lead Dioxide and the Ti substrate?

Palladium is not 'Noble' enough to use in a Chlorate/Perchlorate cell to the best of my knowledge. Only Pt and Iridium will do. Not too sure about pure Iridium but it is use alloyed with Pt.
Don't know about oxides of Palladium being suitable as an undercoat between Lead Dioxide and Ti.

I am tempted to purchase the anode Xenoid has shown as a substrate for an Anode but it would be much too easy and straighforward. Why do that when there is another more time consuming method with no guaranteed successful outcome.
There is virtue in hardship

On a more serious note if one were to purchase the Pt'ized Ti anode as a substrate it could be used again and again as the Lead Dioxide fell off. (so long as it stayed on for a sensible time). If it turned out that you simply could not make a success of Lead Dioxide plating you would still have a perfectly good anode to use for Perchlorate.

I have read reports of people using Platinized Ti anode in the past for (Per)Chlorate making and they complained that the anode failed. Perhaps they were abusing it.


Dann2

IMHO I was under the belief that the platinum coating was to thin and frail for perchlorate use. You made a couple kilos of Potassium perchlorate? May I assume you started with sodium chlorate and generated the perchlorate and performed metasynthesis. Details details! PLEASE!

Quote:

Originally posted by chloric1 IMHO I was under the belief that the platinum coating was to thin and frail for perchlorate use. You made a couple kilos of Potassium perchlorate? May I assume you started with sodium chlorate and generated the perchlorate and performed metasynthesis. Details details! PLEASE!

Well as far as I know, platinised anodes are designed for perchlorate cells. I've just had a good look at my Palloys anode and it seems OK, perhaps a little corrosion starting on the edges. I will be very annoyed if I can't make at least another couple of Kgs with it. If I can make 5 Kgs in total I will be quite happy, that will work out at about $10/ Kg. Actually, I'm not sure what I'm going to do with the 2Kg I have already. I got into (per)chlorate making because I thought I would not be able to obtain cheap KNO3 for rocketry anymore, with NZ tightening it's legislation on the sale of "hazardous substances". So I thought I'd have a go at APC. In the meantime I've located a new source of KNO3, so now I'm not so interested in (per)chlorates.

My perchlorate procedure was essentially as outlined on Dann2's pages. I used a 1.5 litre pickle jar and the starting solution was near saturated, pure (twice recrystallised) sodium chlorate, the cell had about 760g NaClO3 in it. The electrode assembly is shown in the top image, I used two 9.5mm Ti rods for the cathode. Running a perchlorate cell is a dream, clear solution, no chlorine, no smell, no corrosion, etc. I ran it for about 4-5 days at about 15A. I can't remember the details as it was a few months back and I stupidly didn't take notes (as usual). KClO4 was precipitated with saturated KCl solution, I just kept dribbling it in until no more precipitate formed. The description on Dann2's and Alan Yates site about it looking like yoghurt is exactly right. I then cooled the solution and filtered it in a pressure filter. The moist KClO4 was scooped out of the pressure filter and put in plastic containers. I did two identical runs, each produced about 1.2Kg of moist KClO4, which theoretically should be about 1Kg each of dried material. The moist KClO4 is shown in the lower image, I still haven't got around to drying it. It's been in the fridge since I made it, it looks like ice cream now!

I called into the local swimming pool - spa centre today, they had two used MMO chlorinator assemblies sitting on a shelf. i spoke to the assistant (the boss never seems to be there) who said they replace quite a few over summer. They looked OK to me so I'm hoping to get several to try out in chlorate cells. I've had enough of the filthy gouging rods. The assistant wouldn't commit on a price though!

Edit: Changed reference to yoghurt from Dann2 to Alan Yates!
http://www.vk2zay.net/article.php/79

Edit: Changed reference to yoghurt from Alan Yates to Dann2 and Alan Yates! Christ I'll get this right eventually!
http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...

Regards, Xenoid

[Edited on 31-10-2007 by Xenoid]

[Edited on 1-11-2007 by Xenoid]

[Edited on 3-11-2007 by Xenoid]

@Xenoid-That is pretty nice I have a few hundred grams of sodium chlorate that I made as you know from this past August/September. Sunday, I recystallized from distilled water and when I have time, I am going to dry and package it. It would be prudent though for me to test for chloride and barium ions. I know there are places here in the US that sell the same anodes. I will have a look.

I am ony 35 and having problems with memory already. I sometimes find unlabled containers of some salt I made and I cannot remember what it is Yeh I can test it but what a f%^%$ pain when my time to experiment is so short anyways. To add to my frustration, I am almost out of soap and it can be time consuming to make, not to mention curing times. Heated soap is usefull immediately but dissolves immedately and is soft for a week or two. So I may need to buy 2 weeks worth of soap Sorry about my ranting I am hungry and tired and my 2 year old wants to play.

Quote:

Originally posted by chloric1 I sometimes find unlabled containers of some salt I made and I cannot remember what it is

Surfactant, ctab

Suggestion

I rarely met a thesis I didn't like

LiClO4

Lithium Perhlorate Related Processes

Doped Tin Oxide on Ti

maybe etch Ti with oxalic acid instead of HCl

Keep in mind that when you perform this electrolysis and do the metasynthesis that the lithium carbonate is actually less soluble in hot than cold water! Use a heated funnel and filter HOT!

My Cobalt Oxide Anode Experiments

When you dip coat, keep the Ti in a vertical orientation until it drains and drys, or just SHAKE it dry.

Forget the HCl after you have your soluble chlorides it isn't required and actually gets in the way .

Part of the advantage of that mixed valency polymer composition which I posted the patent for a few pages back , was that it wets anything with an adherent film that sticks and leaves a persistent residue which won't wash off .....even on teflon , and that is the effect achieved even before baking . Baking simply hardens
and sets the polymer further and then converts it to a
vitreous conductive coating . But because the film forms in the cold , it blankets the substrate from oxidation during the first heating cycle , as it transitions from the polymer coating to the vitreous coating . That keeps the titanium oxide interface layer thin and conductive .

You mentioned using test tubes as test substrates and that's fine just leave 'em whole and torch the outside
like you are doing . And don't think that an opaque black coating is what you want ...it isn't . What you should see is an irridescent bluish or purplish but transparent coating , something like the reflective optical coatings they put on some sunglasses . You probably know that now from what your ohm meter told you .

I'm still betting that cold coating a solid Ti rod , and chucking it in a rotisserie over a rectangular form burner and spray coating it hot , making several passes , could end up being the best method . The only concern I have here is that on cooling , contraction fractures might appear in the coating on a larger diameter rod , but something like 3/4" diameter or 5/8" diameter would probably be okay . Some of the Ti alloys have 2% Sn
in the alloy and this would probably improve results ,
and some have Zr as well as Sn and these alloys are probably good too . These indigenous metals would tend to contribute to the doping of the Ti oxide interface layer
as it is forming , that contribution to the doping arising from the substrate itself .

[Edited on 25-11-2007 by Rosco Bodine]

Well it's coated...

The wire now has a fairly nice looking, i.e., uniformly dark, adherent, cobalt oxide coating; i.e., I cannot just wipe it off, even when exerting significant force, using a rag. Attached is a picture.

Tomorrow I'll test it in brine electrolysis and see what happens.

I also tried to coat a piece of Ti wire without the oxalic acid anodize pretreatment, and it didn't work at all. It immediately passivated in the CoSO4 solution.

For the sake of comparison, tomorrow I will also try to apply a coating to a piece of platinum wire, and also to a graphite rod. I may also try to put a cobalt oxide overcoat onto a pool chlorinator MMO anode.

[Edited on by jpsmith123]

Hello Xenoid,

I made a little KClO3 with one chlorinator cell (the sal-chlor). I also have another, heavy duty (25 amp) autochlor cell that I haven't done anything with yet. (The completed assembly looks too good to do anything with ...with a 4L PET bottle, titanium hardware throughout, & viton o-rings, I can't bring myself to use it...

Actually I'm waiting to see what happens with these cobalt oxide coatings. My gut feeling is that they'll work nicely over Pt, Pt-on-Ti or MMO-on-Ti, and perhaps over graphite as well.

Who knows, the most practical solution to the perchlorate problem may be to buy a relatively inexpensive sal-chlor cell, take it out of the box, rinse it off, dip it into a CoSO4 solution, electrolyze for a few hours, and thereby end up with a rugged perchlorate maker.

Anyway, right now as I'm typing this, I'm coating a piece of Pt wire. Unlike the Ti wire I just coated, the current is constant in this case, and the voltage is much lower...which makes me think the coated Ti wire has problems. Perhaps I anodized it at the wrong voltage or for too long or something...I'll see tomorrow what happens.

That "blued" band of color above the darker heavier oxide is a good sign


As an alternative to anodization in the oxalic acid , something you might try is a mild cathodization in the hot oxalic acid solution , which should increase the etch rate and bare the Ti even more rapidly .

After awhile at the low etching potential , increasing the negative potential will actually convert the bare Ti to an active hydride , as Ti has an enormous adsorption appetite and capacity for hydrogen .

Whatever you apply next if you act quickly is going to have a virtually bare Ti metal interface to whatever layer is applied next . It would probably deposit a silver metal mirror as a flash coating , if for example you dipped the hydrided Ti into silver nitrate solution . Dittos for the cobalt or mixed tin and antimony compounds , the metals
would probably flash plate electroless and instantly onto the bared Ti .

Another possibility if you are finding a semiconductive
anodization is giving good results , is the "blue titania suboxide" produced by anodization in 50% KOH , which was described in a rectifier patent . That particular inventor had tried many different mixtures and conditions for producing a conductive suboxide under electrolytic , non-pyrolytic conditions , and reported that the 50% KOH
was the only one found to produce a stable conductive Ti suboxide at ordinary temperatures .

Another thing you might test is the "per-cobaltous acid"
as a chemical anodization "first strike" on the hydrided
or freshly etched titanium . This might possibly produce a cobalt doped titanium suboxide interface layer by chemical
action alone . This is pure experimental , as there is nothing in the literature concerning this , simply a curiosity
of my own that arose after reading some of the other experiments that have been described .

Also , the cold soak deposition method is applicable to the cobalt oxides .

Anyway, keep us posted on whatever results you get .


[Edited on 26-11-2007 by Rosco Bodine]

Yeah , that's the Ruben patent for an early Shottky Diode ,

US2711496

Here's the attachment link from page 15 where it was first posted

http://www.sciencemadness.org/talk/viewthread.php?action=att...

I'm still looking for the other reference on the "cobaltous peracid" I mentioned . IIRC it was simple to make using H2O2 added to cobaltous hydroxide . I was thinking that perhaps this might have an effect similar to chromating ,
which can produce a semiconductive and corrosion resistant
very adherent interface , thinking it just might result in a
Titanium Cobaltate "bluing" effect , which would also likely have good adhesion for the cobaltous suboxide applied by electrolysis as the next step .

dann2 is betting on the black stuff being the conductive interface , but I am still putting my money on the blue

Basically this whole semiconductive boundary layer scheme
is indeed the construction of a planar Schottky Diode which
will be operated reverse biased as a Zener , the goal being
the minimization of the reverse breakdown voltage . So
the boundary layer is being doped to optimize its conductivity
in order to minimize the natural rectifying tendency which is exactly opposite the direction of current flow when the cell
is making perchlorate . In this scheme the alloy of titanium
chosen for the substrate definitely will have bearing on the conductivity of the "sandwich" of layers , and so will the additives in the PbO2 or other layers , everything involved
has its own contribution in doping the junctions in the diode structure .

One other possibility I have wondered about is bismuth compounds with cobalt ,
such as bismuth cobaltate , or
cobalt bismuthate ...are these possible and what usefulness
might they have in regards to perchlorate anodes ?


[Edited on 26-11-2007 by Rosco Bodine]

Well my first attempt is looking like a failure...

Which type of graphite rods should I use?

Well I have a piece of Ti wire hooked up as cathode right now in a 10% NaOH solution. It's running at about 100 mA/cm^2. I wonder how long I should leave it in there?

I took the graphite rod out of the solution. It's very hard to see the coating in a picture. The coating seems uniform although it's very thin, and if I rub hard with a rag it leaves a noticeable black trace on the rag.

Hmmmm , give me a minute and I'll check
Yeah it looks like somebody posted it about five months ago in this thread back on about page 18
http://www.sciencemadness.org/talk/viewthread.php?goto=lastp...

Yeah cobalt has a lot of possibilities . The spinels are interesting too as baked coatings , and the cold oxidative soak deposition method works for cobalt oxide too . This
low deposition rate anodic electrodeposition is not wildly different from the cold oxidative soak deposition , and it just might be possible to similarly use a low rate electrodeposition of tin oxide onto titanium by the same scheme . I would expect there is probably an optimum pH and temperature and concentration for the electrolyte , along with an optimum electrodeposition rate which provides the best adhesion .

And the figures from the data charted in the cold oxidative soak method might translate directly to electrodeposition .
A similar chemistry is occurring in either case that is responsible for causing the oxide to "plate out" and the dissolved reagents shouldn't care whether the oxidation
is being supplied from an electrode , or from an oxidant
added to the system , like H2O2 or a nitrate or a bromate ,
as whatever shifts the equilibrium at a similar rate should cause the same result . And electricity for sure does that job . All it takes is something having a higher oxidation potential than the potential of the thing being oxidized
to a less soluble higher oxidation state , and then nothing on earth will keep it from plating out It might even be possible to combine the two methods of oxidative soak and electrodeposition , letting the initial coating deposit via the electroless oxidative soak method which produces that extremely adherent "strike" plating of oxide that is so tough
it can't be scraped off with a knife , and then turning on the current to slowly increase the build rate by electrodeposition , ramping up the process for a seamless
transition in the material .

@dann2

Here is something you might try with some of your mixed chlorides leftover solution . Take a rotary file to some of
your 95/5 wire solder and grind off a half teaspoonful of filings . Boil off any excess HCl , perhaps adding a little makeup water along , until you get a bit of cloudiness or precipitate . Add the filings and stopper the container
and set it aside for a week or longer , a month , whatever . Decant some of the liquid portion and try
it as a dip coating on an oxalic acid etched and hydrided
titanium strip . Then do your baking .

I must say you do seem to have an enduring confidence in the usefulness of HCl as a component in the DTO precursor mixture .


Is trying anything different even distantly on your radar ?

It's not sticking to graphite very well...

@Rosco
It sounds like Dann has actually gotten this to work finally with my Shake & Bake ® method.

Hello,

DTO coating has worked for approx. 7 hours before partial failure.

About testing DTO. Since it mentioned in a patent (or patents) that a shiny black coat would form when the DTO coating was rubbed with a wire brush, I was rubbing DTO coatings with fine steel wool. (OOOO grade) to see of coating would shine or come off. I have not been bothering to do this of late. Just electrolysize in NaCl and see how it goes.
Call it the Dann2 DTO test

About the other possible methods of getting a DTO coat, I don't have time to try everything.
What is wrong with the presence of free HCl in the DTO precusor? It is mentioned in all the DTO (Anode) patents.

I can try without HCl, (No HCl in DTO precursor on radar )
I switched my solvent from ISO Prop. Alcohol to Ethanol. Perhaps this is what made the difference or was it the 'shake and bake'. I will try again with Ethanol with my more usual 'painting' method.
Will also try another two tests without HCl.

It is interesting to note that just about ALL the patent have used Buthanol (I have no Buthanol) as the solvent.

Good luck with the Cobalt. It would be good to leave the Lead behind and move over to a process where one is more comfortable getting one's hands dirty (literally).

To throw something else in I seen in The Perchlorates (see reference section) that there is a Japinese pat. for an LD anode using powdered LD + Vinyl Chloride.
It is in the preface (or is it the history) of the book.
Can Japenese pats he had?

Dann2

[Edited on 27-11-2007 by dann2]